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517 Cards in this Set

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  • Back
What types of cells are considered eukaryotic
The cells of animals, plants, algae, fungi, and protozoa are eukaryotic
What are the major differences between prokaryotic and eukaryotic cells?
Euk are 1 bigger,
2 have a nuclear membrane and nucleoli,
3 more than one chromosome, 4 Mitochondria, endoplasmic reticulum, Golgi apparatus, and lysosomes are present. Chloroplasts may be present.
What size ribosomes do eukaryotes have?
. They have 80S ribosomes in their cytoplasm, composed of a 60S subunit and a 40S subunit. These are composed of rRNA and protein.
How do eukaryotic cells divide?
by mitosis
What is the eukaryotic cytoskeleton composed of?
They have a cytoskeleton composed of tiny rods called microfilaments and intermediate filaments, and cylinders called microtubules.
What are cell walls made of?
Cell walls, when present, are usually cellulose (plants) or chitin (fungi).
What are flagella and are they membrane bound?
Flagella (cilia), when present have a complex structure and are membrane-bounded
What are resting cells called in protozoa and what are they restistant to?
Some protozoa produce resting cells called cysts which are resistant to environmental conditions such as heat and drying
What do fungi produce as reproduction? What is special about them?
Fungi may produce spores which are a means of reproduction. Fungal spores may be somewhat resistant to environmental conditions.
What is found on the cell surface? What is it made of and what does it do?
Cell-surface proteins and extracellular secreted proteins are glycosylated (called glycoproteins). Aids in identification
What are examples of prokaryotic cells?
The cells of bacteria and cyanobacteria are prokaryotic.
What are some differences between eukaryotes and prokaryotes?
1. No nuclear membrane is present.

2. All vital genetic information is usually encoded on one chromosome.

3. They have no membrane-bounded organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, or lysosomes.

4. There are no cytoskeletal elements.

5. Cell division is by binary fission.
How do prokaryotes reproduce?
binary fission
What are the sizes of prokaryotic ribosomes?
70S ribosomes formed of 30S and 50S subunits
What does the bacterial cell wall contain?
Almost all bacteria of medical importance have a chemically complex cell wall containing peptidoglycan (murein).
What is another name for peptidoglycan?
Are bacterial flagella membrane bound?
When they have flagella, they are almost always unsheathed
What kind of projections come from a bacterial cell?
flagella or pili are possible
Are bacterial proteins glycosylated?
no, not normally
Is the surface to volume ratio high or low in bacteria? What does this allow for?
high surface to volume ratio, allows for a high metabolic rate.
What do eukaryotic cell membranes contain?
What makes up the cytoskeleton?
cytoskeleton in eukaryotes only. Made of mircrofilaments and intermediate filaments and microtubules
What is the purpose of petidoglycan or murein?
In BACTERIA only allows for rigidity of the cell wall. Gives bacterial shape and is involved in binary fission
What are the three shapes of bacteria?
coccus, spiral, rod/bacillius

can also be pleomorphic, or variable in size and shape
How big are most bacteria?

Are they visible in the light microscope?
0.5-1.0 μm in width and up to several μm in length

yes, visible by light microscope
What are the 6 most important factors of the bacterial cell wall (peptidoglycan)?
1. It protects cells against osmotic lysis, imparts rigidity, and confers their characteristic shape to bacteria.

2. It determines the Gram staining characteristics.

3. It can cause some of the symptoms of disease.

4. It possesses antigenic properties.

5. Some of its subunits are unique to bacteria.

6. it is the site of action of some antibiotics.
Is the outer part of the bacterial cell includign the cytoplasmic membrane or envelope used more in gram positive or negative organisms?
gram negative
What makes up peptidoglycan (murein)?
alternating units of AMINO SUGARS--
N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM).
Short peptides are attached to NAG or NAM?
to NAM

they NAME the residue,don't nag it
How are adjacent glycan chains held together?
by cross linkages between peptides.
Which amino acids are unique to bacterial cell walls?
D amino acids and D, L-diaminopimelic acid (DAP)
What are the characteristics of gram positive cell walls?
relatively thick, multiple layers of densely cross linked peptidoglycan, may have added peptide bridges, teichoic acids, may have polysaccharides or proteins whihc contribute to antigenicity of cells
What type of bacteria have polysaccharides in their cell membranes?

What is interesting about mycobacterium?
Gram positive might. More specifically, streptococcus do.

These gram positive bacteria produce a waxy substance which makes them more resistant to harsh environments
What makes up teichoic acids?
ribitol or glycerol connected by phosphate bonds
What are lipooteichoic acids?
Acids which are linked to the cytoplasmic membrane and span the peptidoglycan layer.
What is the charge on teichoic acids? What do they do (4 things)?
negative charge, so they bind cations to regulate movement into and out of the cell. Also they mediate adherance to mucosal cells and provide antigenic specificity. Have a weak endotoxin like activity.
What are the features of a gram negative cell wall?
1 more complex than gram positive.

2 peptidoglycan layer is thin and sparsely cross

What is the outer membrane of a gram negative cell envelope made of? What is imbedded in it?
asymmetric lipid bilayer of phospholipid and lipopolysaccharide.

Proteins and lipoproteins are embedded in the lipid bilayer
What are porins? Where are they found? What do they do?
porins are proteins in the gram negative cell envelope which allow for the influx of nutrients and the efflux of waste products across the outer membrane.

They are nonspecific channels that permit the passage of small hydrophilic molecules up to a molecular weight of about 700.

Keeps out enzymes and other larger molecules
Are porins specific or non-specific?
What do specific channel proteins do?
Allow passage of certain substances that are too LARGE for porins

Ex. B12, matodextrins, nucleosides, iron
What types of pathways are responsible for differential penetration and effectiveness of certain beta-lactam antibiotics?
hydrophobic pathways across the outer membrane

note beta lactam antibiotics are active against gram NEGATIVE bacteria
What are the three components of the lipopolysaccharide?
LPS is made of--Lipid A, core oligosaccharide, and the O antigen
Where is lipopolysaccharide (LPS) found and what is its classification?
found in the outer membrane of gram negative envelope. Makes up most of the otuer membrane lipid bilayer.

Where is Lipid A found?

What's its claim to fame?
embedded in the membrane.

toxic to animals

major virulence factor of most gram negative bacteria
What does the core oligosaccharide do?
connects the O antigen to lipid A
What does the O antigen do and where is it found?

What if the O antigen is missing?
important antigenic determinant of gram negative bacteria.

Found as a repeating polysaccharide which extends into the environment.

Without the O anitgen then LPS is LOS lipooligosaccharide
What are 3 functions of the outer membrane?
(i) Its strong negative charge is an important factor in evading both phagocytosis and the action of complement.

(ii) barrier to certain antibiotics, some hydrolytic enzymes, and other environmental chemicals.

(iii) prevents loss of metabolite-binding proteins and hydrolytic enzymes found in the periplasmic space.
Where is the periplasmic space found? What does it contain?
Found between the outer membrane and cytoplasmic membrane of a gram negative organism.

The space is aqueous and contains proteins, oligosaccharides and lipoproteins.
What is the function of the protien, oligosaccharide, and lipoprotein in the periplasmic space?
The protein include degradative, detoxifiying, and binding (for membrane transport)proteins

oligosaccharide is for osmoregulation

lipoprotein connects the peptidoglycan to the outer membrane of the gram neg cell
What do autolysins do?
Autolysins create sites for insertion of newly synthesized peptidoglycan precursors.
What three enzymes prepare for biosynthesis of peptidoglycan?
glycosidases--break glycoside backbone

amidase--releases tetrapeptide from NAM

endopeptidases--attack peptide bonds of side chains and cross links
What are the 7 steps of peptidoglycan biosynthesis?
1. form soluble precursor monomers as UDP-NAG and UDP-NAM

2. add AA's to UDP-NAM to build a UDP-NAM-pentapeptide. Transfer NAM-pentapeptide via udecaprenol

3. then add NAG to get NAG-NAM-pentapeptide (AKA disaccharide pentapeptide)

4. undecaprenol in membrane flips from the inner surface of the cytoplasmic membrane to the outer periplasmic surface.

5. undecaprenol transfers the disaccharide pentapeptide (AKA NAG-NAM-pentapeptide)to the glycan backbone

6. glycosydic bonds are formed

7. transpeptidation forms peptide cross links

COMPLETE cell wall!
What part of peptidoglycan biosynthesis does penicillin disrupt?
The transpeptidation rxn's thus preventing formation of a stable cell wall.
Where are outer membrane precursors formed? How are they transported?

How is the outer membrane formed in gram negative bacteria (e.coli)?

What holds the inner and outer membrane of the gram neg bacteria together?
outer membrane precursors are made in the cytoplasm of the cell, then transferred to the membrane carrier lipid.

the inner and outer membranes are fused to each other at several hundred sites.

The lipopolysaccharide (LPS)molecules are assembled at the inner membrane and then inserted into the inner-outer membrane adhesion sites
Do all bacteria have cell walls?
What group of bacteria do not have cell walls?

What do they have in the cytoplasmic membrane? Where does it come from?
mycoplasma group

have sterols in their cytoplasmic membrane

sterols are acquired from host or environment--they are NOT made by the bacteria
How does the bacterial cytoplasmic membrane compare with the eukaryotes? What's the main difference?

What is the bacterial cytoplasmic (inner) membrane like?
It is structurally similar to the cytoplasmic membrane of eukaryotic cells, except for the absence of sterols in most bacteria

composed of a phospholipid bilayer with proteins embedded in it. The phospholipids and proteins are not static, but move quite freely within the plane of the membrane.
Name 5 functions of the bacterial cytoplasmic membrane which in eukaryotes would each be done by separate membrane bound organelles?
1. enzymes for energy conversion via ATP synthesis (electron transport/oxidative phosphorylation).

2. enzymes for cell wall component synthesis.

3. secretion of extracellular proteins.

4. cell division and an anchoring site for DNA.

5. transport control

It is a selectively permeable membrane, and possesses specific transport activities to allow particular molecules to enter and exit the cell.
What does bacterial DNA look like and how many genes does a chromosome have?
single, continuous circular piece of double-stranded DNA (nucleoid or bacterial chromosome).

Bacterial chromosomes vary in size from about 1000 genes to 6000 genes.
Where is the nucleoid in relation to the cytoplasmic membrane?

Why is this believed to be the case?
nucleoid appears to be attached to the cytoplasmic membrane.

Proteins in the membrane are believed to be responsible for the replication of the bacterial DNA and for the segregation of the new chromosomes to daughter cells during cell division.
What is a plasmid?

How do they replicate?

Are they associated with the membrane proteins?

How many genes do they contain? Are the genes necessary for life? What do the genes protect against?

Can plasmids be transferred from one bacteria to another?
small circular double- stranded DNA molecules.

plasmids replicate independently of chromosomal DNA.

They are also associated with cytoplasmic membrane protein.

They usually contain from 5 to 100 genes which are not crucial for the survival of the bacterium under normal environmental circumstances.

The genes may be for antibiotic resistance, tolerance to toxic metals, production of toxins, or synthesis of enzymes.

Plasmids may be transferred from one bacterium to another.
What does a bacterial ribosomal subunit contain?
Each subunit is composed of one or two molecules of ribosomal RNA (rRNA) and numerous protein molecules
How can you distinguish a growing bacterial cell based on ribosomes?
There are many ribosomes in each bacterial cell. In rapidly growing cells they usually occur as polysomes (polyribosomes) which indicates protein synthesis is occurring.
Are bacterial and eukaryotic ribsomes the same? What uses this to its advantage?
No, they're not the same so some antibiotics expliot this.
What are bacterial flagellum made of?

How is the protein arranged?
globular protein, flagellin

the filament is arranged in several chains that coil together to form a helix around a hollow core.
Where does the flagellum filament anchor?

Anchors in the cell envelope via a 2 part structure--the hook and the basal body.

Basal body = motor
Can bacterial flagella be seen under the light microscope?
Bacteria flagella are ordinarily too slender to be seen in the light microscope, but can be visualized by special stains or by electron microscopy.
Besides movement why are flagella important?
The arrangement of flagella is characteristic of the taxonomic group to which the organisms belong. Not all groups of bacteria have flagella.
What is interesting about the bacteria spirochetes' flagella?
present in the periplasmic space as axial filaments, which are also involved in motility.
What type fo response do motile bacteria show?
Motile bacteria show both positive and negative chemotactic responses
What are flagellar antigens commonly called?
H antigens
Which type of bacteria are much more likely to have pili?
Gram negative

very rare in gram positive
Can bacterial pili be seen with the light microscope?
no--to slender
What are pili (fimbriae) made of?
pilin--forms the shaft of the pilus and a thin tip called the fibrillum
What are the 4 functions of the pili?
1. adhesion pili
2. antiphagocytic
3. disguises that enable them to avoid the immune system
4. sex pili--F pilus which transfers DNA during conjugation
What is the purpose of a common pili?

Where are gonococci found?

How do other bacteria adhere?
helps bacteria to adhere to mucosal surfaces

gonococci in epithelial cells of genitourinary tract

others have pili that attach to surfaces that will be colonized.

E.Coli in urinary tract
Which bacteria has a number of genes co=ding for variants fo pilin? Why is this important?
Neisseria gonorrhoeae

pilin polymerizes to form pili. the bacteria can change enough to fool the immune system and remain.
What are two types of viscous polymers external to the cell wall in bacteria?

What is the difference between the two.
slime layer and capsule.

The capsule is organized and attached firmly. While the slime layer is not.
What are 5 functions of the capsule?
virulence, prevent phagocytosis, promote attachment, protect against dehydration, antigenic
Name a bacteria that uses a capsule as a virulence factor.
Streptococcus pneumoniae
Are capsules necessary for viability?

How can capsules be lost?

can be lost by mutation
What is an example of a bacteria that secretes exotoxins?
Clostridium tetani
What are exotoxins?
secretes toxic proteins
Are exotoxins heat-labile? antigenic?
yes and yes!
What are exotoxins usually reponsible for in disease?
The particular symptoms
Where is DNA located which codes for exotoxins?
On a plasmid
What are the characteristics of an endospore?
highly resistant, metabolically dormant, primarily found in gram positive bacteria genera bacillus and clostridium. They have a core, cortex, and coat
What type of bacteria are more likely to have endospores?
Gram positive Bacillus and Clostridum
What are the three components of an endospore and what do they contain?
1 core-- (consisting of a complete nucleoid, ribosomes, and energy-generating components) enclosed within a cytoplasmic membrane,
2. cortex-composed of peptidoglycan
3. coat--made of protein, and is highly cross-linked with disulfide linkages.
When are spores formed (sporulation)?

Is sporulation used as a means of reproduction?
occurs when nutrients are exhausted or when water is unavailable

may also be part of the developmental process as in vegatative cells

No, in fact one bacterial cell forms ONE spore. used for protection, NOT reproduction
Are spores hydrated or dehydrated?
Where are spores most important? Why?
Spores are important clinically and in the food industry, because they may resist the usual means of infection control or sterilization
Can spores be stained normally?
No, Spores are resistant to the usual bacterial stains but can be stained with special stains
What is the reverse of sporulation? How is it activated?
germination--activated by presence of nutrients or environmental conditions

Then endospore enzymes breakdown layers surrounding endspore, water enters, metabolism resumes, spre converted to a vegetative cell.
What important use can spores serve for a baceria?
storage of intracelluar granules in a polymerized form--metabolic reserves

polymerize in order to minimize osmotic effect

Ex. 1 glucose as glycogen
2 beta hydroxybutyric acid as poly beta hydroxybutyrate 3 phosphate as inorganic polyphosphate (volutin)
What are the two classical methods of microbiology? What are the two newer ones?
older--culture and light microscopy

newer--gene cloning and molecular probes
What minimal ingredients must be in a sterile culture media?
Na, K, Cl--salts
C, N, P, S--energy sources
Mg, Fe--trace elements
Should culture medium be solid or liquid?
Both depends on what you want
What is the best technique for obtaining pure cultures from a mixture of different bacterial species?
solid medium
What is the most common solidifying or gelling agent?

Is it a nutrient?

No, not a nutrient.
What technique is used to find isolated colonies on an agar plate.

What kind of cultures are obtained?

How does it work?

Pure cultures are obtained

This is a method in which the original mixed inoculum is serially diluted, by sequential streaking and spreading with a sterile metal loop.
What steps are necessary in order to quantify bacterial cultures?
serial liquid dilutions on solid media, incubating, counting the resulting colonies, and then calculating the viable titer of the original culture.
What are the units of titers?

Is this the same as cells/ml?
colony-forming units per milliliter (CFU/ml), which may or may not be equivalent to viable cells/ml.
What are bacteria that can synthesize all the organic molecules they need from a simple carbon source called?
Bacteria that require amino acid or other growth requirement in addition to Carbon are called _____?
Bacteria require a multitude of complex organic molecules are called _____?
What kind of medium contains only a carbon source and the minerals required for bacterial growth?
minimal nutrient medium
What kind of medium contains many additional nutrients, such as vitamins, amino acids, etc, but every aspect of the chemical composition of the medium is known in detail
chemically defined medium
How are rich media prepared? Are they chemically defined?
Rich media are prepared by making an infusion, broth, or extract from organic material such as fish, meat, yeast, etc by boiling in water.

They are chemically undefined.
What may be added to media in addition to basic growth requirements?
particular metabolizable compounds (e.g. lactose), inhibitors (e.g. high salt, antibiotics), indicators (e.g. pH-sensitive dyes).
What is a differential media?
Media which will allow the growth of most kinds of bacteria, but which will allow the various colonies to be distinguished from each other by a color change (or some other aspect of their appearance)
What is a selective media?
Media which will allow some bacterial species to grow while inhibiting the growth of most others
What are the 4 main environmental factors important in bacterial viability?
heat, pH, presence or absence of O2, osmolarity
What are the three types of temperature preferences?

For each where is the optimal temp?
psychrophiles--like cold temps
mesophiles--like moderate temps like the human body
thermophiles--grow best at elevated temps

The upper mid portion of their growth range. They slow down toward the extremes

Obligate anaerobes

facultative bacteria


obligate aerobes

obligate anaerobes--no oxygen.

facultative bacteria can use o2 or not, either way they'll live

microaerophilic--needs low o2

obligate aerobe must have o2

capnophilic--requires increased CO2
what is an aerotolerant anaerobe? What is a strict anaerobe?
A strict anaerobe will die in the presence of O2 and aerotolerant anaerobe will not.
Are bacteria usually osmotically tolerant?
Yes, soem can grow in the presence of saturated 6M NaCl
How can increase in cell MASS as a fx of time be determined?

Which is most common and what equipment does it require?
1. Dry weight of cells.
2. Amount of a particular marker, e.g. an enzyme activity or metabolic process.
3. Amount of a particular cell component, e.g. protein or DNA.
4 . Incorporation of a radioactive precursor into cells.
5. MOST COMMON The turbidity of the culture, i.e. the amount of light scattered from or absorbed by the cell suspension. It uses a spectrophotometer
How can an increase in cell number as a function of time be measured?

Which is most common?
1. Direct microscopic
2. Electronic counting in a Coulter counter, or similar device. In this method a defined volume of culture is drawn through a tiny orifice across which an electrical field exists. Each cell that passes through the hole causes a transient increase in the impedance (resistance) and is counted electronically. This method is technically difficult and counts both viable and dead cells.

3. Plate count or viable titer is the most common method.
What does direct microscopic counting require?

Does it count dead or alive bacteria?
small known volume, requires large #'s of bacteria and

counts dead and alive bacteria
What does electronic counting require?

Does it count dead or alive bacteria?
a coulter counter, defined volume thru an electric field, resistance is measured to count.

technically difficult

counts dead and alive cells
Plate count or viable titer is the most common method of counting bacterial cells. how does it work? Does it measure dead or alive cells?
1. bacterial culture is serially diluted so that about 100 colonies are available.

2. Incubate

Only measures viable cells. Slow and sensitive technique
What factors indicate how fast a bacterial population will double? What is this known as?
species, culture medium, temperature

generation time or doubling time
What is the generation time or doubling time inversely proportional to?
The growth rate
Do bacterial cells grow exponentially or arithmetically?
What isthe equation that gives the number of cells present in successive generations (Nn)
Nn = 2^n No

where n is the number of generations of growth
Will a semilog plot have a straight or curved line?
straight--the slope of the line gies alpha or the growth rate constant
What are the four principle phases of growth in a bacterial culture w/o nutrients?
Lag phase--preparation, slow growth

Exponential phase--log phase, constant growth

Stationary phase--exhausts nutrients

Death phase--decline in viable population, decreases exponentially
What must be in effect for a continuous culture technique to work?
must keep at least one nutrient in limiting amount so cells don't reach the stationary phase

Volume is kept constant and is continuously diluted with fresh medium
What is the limit of resolution on a light microscope?
200 nm or 0.2um
What are the two types of magnifying lenses on a light microscope?
ocular and objective
What is true of the 100X lens on the light microscope
oil immersion--increases resolving power
What do microbiologist commonly use to look at specimins?
What is the most common staining method how does it work?
Gram stain,

1. Begin with crystal violet--primary stain

2. Iodine--the mordant (fixer)

3. Organic solvent to decolorize

4. Safranin--pink counterstain
What color do gram negative bacteria stain? Why?
stain pink--the purple primary is washed out with the organic solvent because of the weak bonds of the cell wall.
What color do the gram positive bacteria stain? Why?
primary stays in the cell wall because of strong bonds. It is not washed out by the organic solvent.
Do Gram-positive or Gram-negative organisms take up the crystal violet and the Gram's iodine which form a purple complex inside the cells?
Both do. It is a matter of which is washed out with the organic solvent. (gram neg is washed out because of weaker bonds in peptidoglycan cell wall)
Why are aged cells tricky?
Thy may appear gram negative when they are in fact gram positive because of degradation of cell wall due to autolytic enzymes
How do bacteria look under a light microscope when unstained? How can this be overcome? How can living bacteria be seen?
Appear transparent

overcome by changing optics, use phase contrast or narrow the cone of illumination

Can see living bacteria in wet mount. or by dark field optics.
Which bacteria is often observed by dark field optics? How does it work?
Treponema pallidum appear bright and luminous against the dark background but can't be seen under normal circumstances.

use a special condenser with a stop to block light in the center field
What's the difference between transmission and scanning electron microscopy?
scanning views the outer surface while transmission can see inside the cell. Both use beams of electrons to do their work
How do bacteria divide?
by binary fission
What must be duplicated in order for a bacterial cell to divide?
All the components of the cell must be duplicated before the cell can divide. This means that the cell must regulate and coordinate the biosynthesis of all its components. This includes the bacterial chromosome, which must be replicated
What does a bacterial chromosome look like?
single large circular DNA molecule
What is a nuceleoid?
bacterial wanna be nucleus- supercoiled chromosome forms a compact structure called the nucleoid.
How does DNA repliation proceed?
bidirectional, with two replication forks diverging from the origin. They meet at the terminus to complete replication.
How many replication forks exist at once?
Thus multiple replication forks may exist at one time.
How is frequency of initiation of DNA replication regulated?
regulated in response to increases in cell mass AND regulatory proteins which act at the origin of replication to prevent or allow formation of replication forks.
What is a replicon model?
regulatory mechanism which controlls regulatory proteins at origin of replication. Allows or prevents replication
What must follow each new round of DNA replication?
cell division
How does a bacterial cell divide?
invagination of the cell membrane forming a division septum.

Segragation of daughter chromosomes, probably doen by origin of replication sites on the cell membrane; an aspect of replicon model
Do bacterium grow synchonously?
No asynchronous. Each bacteria species has its own natural range of growth rates, which can be further influenced by availability of nutrients and oxygen, temperature, and other environmental factors.
Cell size is a function of ___?
growth rate. lager cells are rapidly growing
Which is more metaboically diverse: prokaryote or eukaryote? Why?
prokaryote, Use of oxygen, products for potential use more diverse than eukaryotes. Used in classification of bacteria
What are the two types of metabolism?
anabolism and catabolism.
What do exoenzymes do?
facilitate uptake of nutrients
Which type of cells have a periplasmic space?
Gram negative cells
Where do exoenymes work?
In the periplasmic space of gram -, and they degrade large molecules OUTSIDE of the cell
Cna hydrophobic molecules pass directly thru the cell membrane
Yes, membrane is lipid
How do water and ammonia get thru the cell membrane?
simple diffusion
What type of bacteria use carriers?
Both gram + and - use active transport, group traslocation, facilitated diffusion
Is a transport molecule modified in active transport?
Is group translocation energy dependent? Is the nutrient modified?
Yes and Yes. Need energy and modifiy nutrient in group translocation. The modified molecule is UNABLE to leave the cell
Does facilitated diffusion require energy and does it move against or down its concentration gradient?
facilitated diffusion does NOT use energy and moves down its gradient. Requires facilitation o f a specific protein carrier in the membrane
What does rapid hydrolysis achieve?
lower concentration inside the cell, to allow a molecule to enter cell spontaneously. Can also TRAP molecule inside by converting it to a form that cannot bind with a carrier protein
What is an autotrophic bacteria?
use oxidized carbon (carbon dioxide) as their MAIN carbon source, and PHOTOSYNTHESIS OR OXIDATION of reduced inorganic compounds as a source of energy and reducing power.
What is the difference between an autotroph and a heterotroph?
a heterotroph uses organic molecules as an ENERGY and C source

An autotroph uses oxidized C (CO2) as main C source, and photosynthesis or ox of inorganic cmpds as energy source
Are most bacteria auto or heterotrophs? What about pathogens?

ALL pathogens are heterotrophs
What molecules act as energy carriers?
ATP, GTP, UDP, reduced pyridines: NADH AND NADPH
How is energy captured?
as ATP, pH gradient, etc
Are high energy precursosr reduced or oxidized?
Are the following reduced or oxidized? Methane? Carbon dioxide? Fatty acid? Glucose? Pyruvate? Lactate?
methane--reduced; carbon dioxide--oxidized; Fatty acid--reduced; Glucose--50/50 reduced/oxidized; Pyruvate--oxidized; Lactate--reduced
What are the two types of metabolism? Which uses oxygen?
respiration and fermentation

respiration uses oxygen (or N) as terminal e acceptor(glucose to pyruvate to TCA to ETC etc), fermentation doesn't (lactate)ATP generated directly
How many ATP produced via respiration? fermentation?
What is the Pasteur effect?
When fermenting bacteria, which have a high consumption rate of glucose, are given O2, the rate of glucose consumption drops abruptly
The hexose monophosphate shunt uses what instead of NADH? What is its function?

reduces lipids and yields pentose phosphates for nucleic acid biosynthesis. Also converts glucose to pyruvate kind of like glycolysis
What is the Entner-Doudoroff pathway?
thrid way to get from glucose to pyruvate in some bacteria. ONLY YIELDS 1 ATP PER GLUCOSE
What is the Strickland rxn?
fermentation of aa instead of sugar
What are products of catobolsm used for?
Where is the cells supply of ATP? What happens when it is needed elsewhere?
The cell's supply of ATP is located in the cytoplasm, and can be used to energize the synthesis of macromolecules which occurs in the cytoplasm or in the nucleoid (which is intimately associated with the cytoplasm).

But ATP cannot be directly used to drive the synthesis of macromolecules such as peptidoglycan, lipopolysaccharide, or capsular polysaccharide, which are synthesized outside the cell membrane where there is no ATP. Such extracellular biosynthesis is driven by energy stored in a membrane carrier lipid called UNDECAPRENOL PHOSPHATE
What form of energy does undecaprenol phosphate use?
What types of extracellular proteins are secreted from the cell?
1. toxins 2. components of cellular appendages(flagella or pili) 3. periplasmic proteins
How do extracellular proteins get to their destination?
syntesized on ribosomes like peptidoglycan etc, then get to extracellular location by: ex. Type III, IV hypodermic needlike action, which increases virulence. OR directed by signal sequence, ie. N terminal (1st synthesized) passes thru membrane while C end synthesized.
How is Fe metabolized by bacteria? Is Fe necessary for bacterial life?
Hard to get at in human body b/c trapped by hemoglobin, myglobin, transferrin, ferritin etc. Bacteria w/ SIDEROPHORES have high affinity for Fe and take it away. Also have transporters for the Fe complex and Fe is released into the bacterium.

Yes Fe is a nutritional requirement for bacteria.
What is a critical item? Semicritical? Non-critical?
• Critical items-items introduced into the body-should be sterile.
• Semi critical items-items which have contact with mucous membranes and items such as respiratory therapy equipment-sterilize if possible; if not possible, use high level of disinfection preceded by proper physical cleaning.
• Noncritical items- use cleaning and low level disinfection (Items such as face masks, EKG electrodes, bedpans, walls). Even stethoscopes can carry bacteria from one patient to another.
What is the difference between sterilization and disinfection?
Sterilization kills endospores, disinfection does not.
What types of antimicrobial agents are used on living tissue? Non-living?
Living--anticdeptic and antibiotic

Non-living--sterilant, disinfectant, sanitizer
Does decontamination ensure that an item is safe for patient use?
Which is more effective: 100 or 70% ethanol?
70% ethanol is more effective; used as a disinfectant (not sterilant)
Are detergents disinfectants? What about quaternary ammonium compounds? How do they work?
No, they remove organisms from survace. Quaternary ammonium compounds are used for skin antisepsis. Work by disrupting cell membranes.
How do phenols work? What cleaner contains phenols?
damage membranes and denature proteins. Found in lysol. Very hydrophobic and good at killing.
How does chlorine work?
hypochlorite is a strong oxidizing agent kills sulfhydryl cross links and inactivates microbe proteins. Kills anthrax,
How does iodine work?
iodine is an oxidizing agent, like Cl. Betadine commonly used.
How do heavy metals work?
Heavy metals act on sulfhydryl groups as do Cl, and I
Which antimicrobial agents work by disrupting the sulfhydryl groups?
h202, I, Cl, heavy metals
Which chemical is used as a skin antiseptic?
Which microbes are resistant to h202?
those that produce catalases--inactivates H202.
How does formaldehyde and gluteraldehyde work?
denatures proteins and nucelic acids AND alkylates proteins
What type of disinfectant is used to clean bronchoscopes?
formaldehyde and gluteraldehyde
Which chemicals denature proteins and nucleic acids?
ethylene oxide, formaldehyde, gluteraldehyde, acids, alkalis, alcohol, detergents, phenols
What is ethylene oxide used for?
gas sterilization in hospital for heat sensitive equipment
In addition to denaturing proteins how do acids and alkalis work?
alter pH and homeostasis
How do dyes work? Which type of bacteria are more suceptible to malacate green?
inhibit growth by binding to nucleic acids.

Gram negative bacteria--LJ slants
Which is a better killer: moist or dry heat?

Why isn't boiling a good enough killer? What should be used instead?
moist aids in denaturation by allowing h20 to bind and stabilize denatured structure.

Boiling won't inactivate spores. But autoclaves will.
What level of UV light is necessary to kill microbes? What microbes are sensitive to UV light and what must be taken into consideration as far as UV light is concerned?
250-260 nm

Myobacterium tuberculosis

distance from UV source is important--should be short distance
How can microbes be separated from a liquid? What is the benefit over autoclave?
By filtration.

Immunogenic lysed bacteria are absent, but may be present in autoclave
What is efficacy dependent on?
• Nature of ITEM being disinfected or sterilized- more porous = harder to disinfect or sterilize.

• Nature of ORGANISM

• Type of GERMICIDE used

• CONCENTRATION OF GERMICIDE (each has its optimum) - In general a higher concentration results in more killing. There are exceptions: ethanol is actually more effective at 70% than at 100%.

• CONCENTRATION OF ORGANISMS: more organisms = less efficient killing

• DURATION, TEMP, AND pH of exposure- many times longer duration, higher temperature, and lower pH enhances killing

• PHYSIOLGOICAL STATE OF ORGANISM, actively growing organisms are easier to kill while stationary phase cells and spores are harder to kill.

• Presence of extraneous organic matter
From greatest to least resistance of disinfection or sterilization rate the following: nonlipid or small viruses, mycobacteria, fungi, bacterial spores
bacterial spores, mycobacteria, nonlipid or small viruses, fungi
What is the phenol coefficient and what does it mean if >1 or <1?
phenol coefficient rates how well a germicide sterilizes. Greater than 1 is more active and less than 1 is less active.

Not used much and not very accurate
How frequent are bacterial mutations?
Mutations occur spontaneously at a frequency of about one in a million per gene, per generation.
What is a transposon?
Mutatoin caused by transposing DNA
Are frameshift mutations always troublesome?
No, frameshift mutations may cause no problems
Are bacteria haploid or diploid? What does this implicate?
haploid--single chromosome. It means that every gene that if there is a mutationi it will be expressed. there is no such thing as dominant and recessive in bacteria
How many base pairs are in a bacterial gene? Codons? MW of typical protein?
1KB= 100 base pairs

300 codons

30,000 daltons MW
What is a bacteriophage? What kind of parasite is it?
virus that uses bacteria as a host. dependent on bacteria. AKA phage. OBLIGATE INTRACELLULAR PARASITES--completely dependent on bacteria for reproduction
Can a phage perform metabolism outside of a bacterial cell? How does it get inside a bacterial cell?
No, must be inside bacteria. Gets wrapped in a protein coat--CAPSID.
What does the phage genome consist of ? What is the capsid structure?
ss or ds DNA or RNA. Linear or circular. Might contain unusual nucleotides.

Capsid--filamentous and helical OR icosahedral (soccer ball). May have tail to inject genome to bacterial host
Is the capsid injected into the bacterium? What is a virion?
Never! A virion is a phage particle
What are the steps of the lytic cycle?
adhere, inject, express, produce gene products (capsid etc), self assembly of virions, lysis of host cell to release progeny phage.
What is a phage called that can ONLY perform the lytic cycle? What is the other option?
virulent phage.

Temperate phages can do the lytic cycle, but can turn it off and intermittently perform the lysogenic cycle.
What is the lysogenic cycle?
A phage produces a repressor to stop the lytic stage. The stop may last for decades. Prevents cell from being killed AND prevents the production of phage. The phage genome is integrated into the bacterial DNA linerally and passively replicates.
What effect do lysogenic or temperate phages often produce? What is lysogenic conversion?
Transfer coding for toxins, which are expressed by the host,i.e., non-toxic can become toxic--lysogenic conversion
What is a prophage?
phage genome
What are the three methods of bacterial genetic exchange? Describe each.
TRANSFORMATION (transfection)--naked DNA is introduced into the bacterium, which must be COMPETENT
TRANSDUCTION--when dna is transferred via a phage w/ in the capsid-accidental. There is generalized and specialized
CONJUGATION--2 cells get close enough together and then directly transfer by sex pilius (F factor)etc.
By conjugation is ss or ds DNA passed?
ss transferred made into ds inside
When DNA is transferred what important fragement is not available? What must be done?
origin of replication. Need to do genetic recombination, spec. HOMOLOGUS RECOMBINATION--incoming DNA fragment lines up with resident chromosome and substitutes its DNA for resident's DNA--incorporate permanently
What can the three methods of genetic transfer do for science?
Can create a genetic map. sequence DNA . Have complete sequence of 20, 50 more in progress
What is a plasmid? What is its size? What is its most important characteristic?
A plasmid is a circular piece of DNA--kind of a small chromosome. < 1% size of bacterial chromosome. CAN REPLICATE AUTONOMOUSLY--HAVE OWN ORIGIN OF REPLICATION
How do plasmids transfer? What is R factor? What type of genes are often found in plamsids?
by conjugation.

Resistance factor, many plasmids have--antibiotic resistance, often multiple.

Toxin genes often found in plasmids
By conjugation is ss or ds DNA passed?
ss transferred made into ds inside
When DNA is transferred what important fragement is not available? What must be done?
origin of replication. Need to do genetic recombination, spec. HOMOLOGUS RECOMBINATION--incoming DNA fragment lines up with resident chromosome and substitutes its DNA for resident's DNA--incorporate permanently
What can the three methods of genetic transfer do for science?
Can create a genetic map. sequence DNA . Have complete sequence of 20, 50 more in progress
What is a plasmid? What is its size? What is its most important characteristic?
A plasmid is a circular piece of DNA--kind of a small chromosome. < 1% size of bacterial chromosome. CAN REPLICATE AUTONOMOUSLY--HAVE OWN ORIGIN OF REPLICATION
How do plasmids transfer? What is R factor? What type of genes are often found in plamsids?
by conjugation.

Resistance factor, many plasmids have--antibiotic resistance, often multiple.

Toxin genes often found in plasmids
Does a plasmid need to recombine with bacterial dna?
no, it can replicate autonomously, so there is no need
What are the types of transposable elements?

Which is smallest?
insertion sequences, transposons, and certain temperate phages which integrate at random into the chromosome

Smallest is isertion sequence (20-40 BP)
What does an intertion sequence look like? What do they encode for?
Has inverted repeats on each end (2 total). Encode for transposase.
What does transposase do?
recognizes inverted repeats at two ends of the element AND catalyzes transposition to new site
What happens if an insertion sequence hops into the middle of a gene?
most likely disrupt activity and cause a mutation
What is a transposon? What important function does it have?
segment of DNA containing an antibiotic resistance gene and having an insertion sequence on each end. When it transposes to a new site (e.g. onto a plasmid) it carries the antibiotic resistance gene with it. This is how R factors come to exist.
When was gene cloning developed? Describe the process.
1970's. fragment(s) of DNA from any organism can be incorporated into a cloning vector which is then put inside a bacterium to be replicated, so that the cloned DNA fragment will be replicated as well.
Where do cloning vectors usually come from? What is the absolute requirement for the vector??
Come from plasmids, some from phages.

MUST be a replicon, ie have a origin of replication
What is used to cut DNA? What other function do they serve?
restriction endonucleases. Cut AND convert circular TO linear
What does DNA ligase do?
links the ends of linear dna, to form circular
What is the end product of gene cloning?
large amounts of cloned gene, and large amounts of protein encoded by that gene
What is the major difference of gene expression in bacteria and eukaryotes?
Eukaryotes have introns that need to be spliced out. Code for nothing
How does most gene regulation take place?
By binding of a regulatory protein either activating or repressing gene expression
Describe the lac operon. Is this an ex. of positive or negative control?
lac operon. Lactose controls regulatory protein. The protein is bound to the operon when lactose is NOT present. When lactose IS available it binds to the regulatory protein, which is then removed from the operon, and expression can occur. NEGATIVE control.
What is an operon?
group of adjacent genes which are co regulated
What does the lac Y gene correspons to? lac Z? What do each do? Which is transcribed first?
lac Y--lactose permeas--brings lactose in the cell membrane
lac Z-beta galactosidase--cleaves into glucose and galactose.

Lac Z transcribed first
What is meant by negative control? Give 2 examples.
The promoter itself is sufficent to allow transcription to occur, as long as it isn't blocked (negative)

Ex. lac operon and lysogenic response.
What is positive control? Give an example?
positive control is when the promoter is NOT strong enough to bind RNA polymerase and start transcription. Matose metabolism.
How does positive control work?
Add an initiator (activator) protein, to help the weak promoter (positive!!)
How does the maltose operon work?
When maltose is available, so is the initiator protein. And visa versa when it is not.
What do positive and negative control have in common?
Both have regulatory proteins that respond to physiolgoical signals, which influence the PROMOTER in order to regulate expression of genes.
In addition to regulatory proteins for specific genes what is another form of regulation and how does it work?
Global regulation.entire groups of genes scattered all around the chromosome are under common control, so that ONE physiological signal can turn them all on or off at once
When does global regulation occur?
during repair of damage to DNA, the switch from aerobic to anaerobic growth, heat shock and other stress, the activation of virulence genes during the establishment of an infection, and the preferential utilization of glucose instead of other carbon sources (catabolite repression).
Are genes affected by global regulation all clustered around an operon?
No, they are throughout the genome.
How is potentially lethal DNA damage repaired? What genes are involved and how are they activated?
DNA damage leads to breakdown of damaged DNA products. This activates recA protease, which destroys lexA repressors. Elimination of the repressor allows genes to turn on and enter the SOS RESPONSE
What are pathogenicity islands?
pathogenic bacteria, which are similar to others EXCEPT for large DNA insterts (35-190KB). ALIEN to species and confer pathogenicity.
What is believed to cause pathogenicity islands?
that transposable elements or temperate bacteriophage have been involved in the introduction of pathogenicity islands into bacterial genomes.
What factors contribute to difference in disease?
infecting dose, differences in virulence, differences in the host population--immunity, immunodificiency, weaknesses in host defense. AND MHC and toll-like receptors (TLR)
Which has a faster geneeration time: microbes or humans?
microbes :)
Why does selection favor less virulence? When is this untrue?
because the host needs to be alive in order for the bacteria to thrive.

Not true when 1. hosts are abundant, poor hygine Ex. Prison. 2. in emerging diseases. [start out high virulence; evolving toward less virulence]
What are the 2 main categories of source of infectious disease?
1. endogenous (normal flora) Ex. urinary tract infection
2. exogenous (other people, animals, environment, point source, or diffuse source)
What is an ex. of a diffuse source of infection? A point? A fomite?
diffuse--tetanus in dirt gets into wound.
point--AC has legionarres spores
What is the term for infection aquired from animals?
What are routes of transmission?
direct contact, fomites, respiratory, GU, skin, food/water, fecal oral, traumatic injury, arthropod vector.
Give ex. of arthropod vector.
tick gets pathogen from mice or deer, bites human get lyme disease.
What are the general steps of pathogenic sequence?
1. adherence
2. colonization
3. invasion
4. disruption or avoidance of host
5. damage host
What are the characteristics of staphylococcus? What do they look like microscopically? What family do they belong to?
Gram-positive, non-sporulating, non-motile cocci, form grape like clusters, are often pigmented (pale yellow), might be surrounded by zone of hemolysis (usually beta) Belong to the family Micrococcaceae
Can staphylococci grow in salt? What do they look like when grown on solid media?
Yes, in 8.5% NaCl. On solid culture media look porcelin like, opaque.
Are staphylococci aerobic or anaerobic? What enzyme do they produce to protect against bacteriacidal phagocytosis?
both--faculative. perform both fermentation and respiration.

catalase, which breaks down hydrogen peroxide to form water and oxygen. Catalase may help to protect staphylococci against oxygen-dependent bactericidal mechanisms of phagocytic cells.
What are the 3 medically important species of staphylococci?
1. aureus
2. epidermis
3. saprophyticus
What are the types of hemolysis?

What are characteristics of alpha and beta?

What type of bacteria usually exhibit alpha hemolysis?

What is alpha hemolysis due to?
alpha, beta, gamma (means absense of hemolysis)

alpha--partial destruction of RBC, AND zone ofpartial clearing AND greenish discoloration around colony. NOT normally seen in staphylococci. Seen in streptococci. DUE TO H202 PRODUCTION.

Beta hemolysis--complete or near complete lysis AND clearing of RBC's w/ NO greening of agar. Extent is variable.
What is a non-pathogenic staphylococci? How can it be differentiated from pathogenic staphylococci?

non-pathogenic staphylococci 1. produce acid from glucose anaerobically
2. are sensitive to lysostaphin
3. produce acid from glycerol in presence of erythromycin
What are the characteristics of S. aureus? What are the definitive test for it?
most significant as a human pathogen.

ribitol teichoic acid, often produces a yellow or gold pigment

typically beta hemolytic on blood agar

ferments mannitol

some strains of S. aureus do not produce the typical golden yellow pigment

definitive identification depends upon ability to produce the plasma-clotting enzyme COAGULASE, or upon DNA hybridization analysis.
What % of population carry S aureus in the nasopharynx? What is another site of asymptomatic carriage? Who's more susceptible to carry the pathogen?
15% in nasopharynx. Perineum also site of carriage. Hospital workers are susceptitable.
What is coagulase? What are the two forms? How do they differ?
Coagulase interact with fibrinogen in the plasma.

Two forms: free and bound

free acts in cooperation with another plasma protein to CLEAVE FIBRINOGEN and coagulate or clot plasma.
BOUND-- in the membrane, acts directly on fibrinogen to CONVERT TO FIBRIN and cause the bacterial cells to clump.
What are the 2 lab tests to decipher between bound and free coagulase?
slide for bound and tube for free. Both detect clotting. Slide can also detect fibrinogen coated latex beads.
What does novobiocin resistnace indicate?
S. saprophyticus infection.
What is the difference between plasma and serum?
Serum doen't have clotting factors

Neither have blood cells
What are the characteristics of Staphylococcus epidermidis? What is it's group specific antigen and what is it made of?
Staphylococcus epidermidis non-pathogenic

opportunistic pathogen in compromised hosts

forms smaller colonies than S. aureus

usually non-hemolytic (gamma)

white pigment

NO coagulase, protein A, or exotoxins

does NOT ferment mannitol

It contains glycerol teichoic acid, which is a component of its group-

specific antigen, polysaccharide B.
Where does S. epidermidis show up?
contaminanted blood cultures, Disease caused by coagulase-negative staphylococci is often associated with colonization of surgically implanted prosthetic devices.
Where is Staphylococcus saprophyticus found? What are its characteristics? What is its definitive test?
Second most common cause of urinary tract infections in sexually active young normal flora of human skin in the genitourinary area and is novobiocin resistant--determinant, i.e. rules OUT S. aureus.
What are 3 typings that are used to differentiate bacteria?
1. serum (Ag differences)

2. biological (metabolic differences)

3. phage typing (below the species level--for specific strain, epidemic trace)
Why is phage typing useful in epidemic tracing?
Because it can determine the specific causse by using page receptors. Each strain will have specific phage receptors
How many major phage groups of staphylococcus have been determined?
5--each wiht numerous phage types
Does S. aureus possess a capsule? Where are capsules more frequently found among staphylococci? What is a capsule used for in these staphylococci?
S. aureus do not possess a capsule. Capsules are more frequently found among coagulase-negative staphylococci such as S. epidermidis, where they may be present as a glycocalyx that can be important for non-specific adherence to surfaces.
What do Staphylococci have attached to their peptidoglycan and cell membranes? What are two important modified types?
Staphylococci have teichoic acids attached to their peptidoglycan and cell membranes. Include: polysaccharide A and polysaccharide B.
What is the group specific antigen of the cell wall of S. aureus?
Polysaccharide A, modified with N-acetyl-glucosamine,
What do Teichoic acids mediate?
the attachment of staphylococci to mucosal surfaces through their specific binding to fibronectin.
Are antibodies against teichoic acids protective against staphylococcal infection?
No, although they may be indicators of persistent systemic infection.
What protein binds to IgG? Which bacteria most likely posses it? How does it attach? Is it an antigen? What is its importance?
Protein A binds immunoglobulin IgG

most S. aureus strains uniformly coated with protein A, also secreted from the cell.

covalently attached to the peptidoglycan, by its Fc region

protein A is not behaving as an antigen in this case, EVEN THOUGH IT IS BOUND TO AN Ab!!!

When S. aureus gets into the blood stream, the binding of IgG to protein A causes the cells to become coated with (reversed) human antibody molecules in a way that prevents them from being recognized as foreign by the immune system, so protein A functions as a virulence factor.
Does S. Epidermis have Protein A?
Why are more than 90% of S aureus strains resistant? What encodes for the resistance?
ß-lactamases(penicillinases) degrade penicillin by cleaving its ß-lactam ring. encoded by transmissible plasmids (R-factors)thus rapid spread
what are MRSA's ? What causes resistance? What % have emerged? What can treat MRSA's?
methicillin resistant staph aureus strains. methicillin is a semi-synthetic penicillin. Resistance due to : chromosomal mutations that alter the structure of the penicillin-binding proteins (PBP's) on the cell membrane that are the targets of the drugs. 30-50% MRSA. High levels of vancomysin can treat.
What do some strains of S. aureus produce that can cause staphylococcal food poisoning? What % cause food poisioning?
enterotoxin 30% to 50%
What type of toxin does S. aureus produce which damages membranes? What are these sometimes related to? What are they?
at least 5 cytolytic toxins, alpha, beta, gamma, delta toxins, and leukocidin.

beta is dame as Beta hemolytic, but alpha and gamma are DIFFERENT.

cytolytic toxins during natural infections may be directed toward some cell types other than erythrocytes, since some of them are capable of lysing many different cell types, resulting in tissue necrosis. These cytolytic toxins disrupt cell membranes by a variety of mechanisms
What does alpha toxin do? Is there enzymatic activity? Are pores formed? Where is the gene located?
- not to be confused with "alpha hemolysis". The most important of the cytolytic toxins. It is toxic to many types of cells. inserts into hydrophobic regions of membrane, disrupts integrity. It does not seem to possess any enzymatic activity, and may involve formation of pores. The gene for alpha toxin appears to be associated with a transposon, which is present on both the bacterial chromosome and on a plasmid.
What is Beta toxin analogous with? Does it produce an enzyme?
Beta toxin= Beta hemolytic - toxin IS an enzyme called sphingomyelinase C, which acts by degrading membrane phospholipids in a variety of cells.
What is Gamma toxin used against mainly?
Gamma toxin - not to be confused with "gamma hemolysis". This toxin is mainly active against erythrocytes.
How does delta toxin work? Is it heat stable?
this toxin seems to disrupt the membranes of many different cell types by a detergent-like action. It is hydrophobic and thermostable.
What does leukocidin do? How does it provide protection to bacteria? What is it composed of? Does it form pores?
not active against erythrocytes. is against leukocytes, active against phagocytic cells, bacteria which produce it have increased resistance to phagocytosis. It is composed of two different protein subunits. it causes membrane leakiness by the formation of pores
What other toxins are available besides cytolytic? What are these resistant to?What do they act on? Where are their genes located?
6 serologically distinct enterotoxins, called A, B, C, D, E, and G. These enterotoxins are resistant to boiling, although not to autoclave temperatures. resistant to digestion in the stomach. act on the central nervous system to produce vomiting, are pyrogenic (fever) and activate mitosis in T-lymphocytes.

genes for some of these enterotoxins may be located on the genome of lysogenic bacteriophage (lysogenic conversion).
What is TSST-1 and what is it related to? What does it do?
toxic shock syndrome toxin (TSST-1), was formerly known as staphylococcal enterotoxin F--related to enterotoxins resistant to boiling etc--so similar effects, i.e. activated immune system, producing large amts of of IL-1 (inflammation), IL-2 (proliferation of T cells), and TNF (cytokine--tumor necrosis factor, stimulates T cells)
The staphylococcal enterotoxins and the related toxic shock syndrome toxin are members of what group? How many are there total? What are they able to do? Is this good or bad?
12 total (5, 6, 1)superantigen toxins--Able to broadly trigger the immune response by activating major subsets of T lymphocytes, thus causing the release of large amounts of lymphokines and resulting in strong physiological reactions. this "non-specific" immune system activation disrupts cytokine networks and leads to a deranged, disorganized, and ineffective immune response.
In addition to the superantigens what does S aureus produce? What does this cause? How does it work?
exfoliatin(exfoliative or epidermolytic) toxin. SSS scaulded skin syndrome mostly in infants. (A and B forms)Contain serine proteases that disrupt desmosomes.
Name the six enzymes produced by staphylococci.
coagulase,staphylokinase,hyaluronidase,DNAase,beta-lactamases, lipases
What are the functions of coagulase and staphlokinase and what is their relation?
coagulase--forms clots
staphlokinase (fibrolysin)--breaks clots. Together they determine thickness of blood clots around a staph infection
Which enzyme is abundant in pus due to the lysis of PMN's (neutrophils)?
DNAase. the DNA makes pus very viscous, and it may be beneficial to the staphylococci to reduce that viscosity or to release nucleotides from the DNA for their nutrition
What type of plates do staphylococcal infections grow on? What tests can be done?
blood agar and mannitol salt agar plates. Catalase and coagulase tests.
What types of cutaneous and subcutaneous infections result from S. Aureus?
a. Cellulitis

b. Folliculitis, furuncles, carbuncles

c. Impetigo

d. Wound infections

e. Paronychia, blepharitis, postpartum mastitis

f. Increased nasal carriage and cutaneous infection in ARC and AIDS
What types of systemic/hematogenous infections result from S. Aureus?
a. Endocarditis/bacteremia/septicemia

b. Osteomyelitis

c. Septic arthritis

d. Lung abscess/pneumonitis/empyema

e. Foreign body infections, IV's, prostheses, catheters, etc.

f. UTI's of hematogenous origin
Other staph infections from S. Aureus.
3. Staphylococcal toxic shock syndrome

4. Food poisoning

5. Staphylococcal scalded skin syndrome/bullous impetigo
Is steptococcus gram + or -?
gram +
Does streptococcus produce spore? Is it motile?
no and no
Does streptococcus produce catalase?
No catalse
Where is streptococcus normally found? what are teh pathogenic species of strep?
normally found in the orgal cavity--normal flora.

S. pyogenes and S pneumonia. Note: enterococci are now their own genus--enterococcus
What type of medium do strep grow well in and what do they look like?
Step grow well on a rich broth and grow as diplococci or more typically as chains.
Do streptococcus grow on blood agar plates?
Yes, they form small to medium colonies
What are the nutritional requirements for streptococci? Oxygen?
They are fastidious in nutrition and faculative, however they do not use oxygen Note: Peptostreptococcus are strictly anaerobic.
Are streptococci capnophilic?
Some are, yes.
Why don't streptococci use oxygen?
The don't have ETC etc to perform respiration.
How can streptococci be identified?
not thru hemolysis, antigenic composition or growth characteristics or biochemical rxns but thur Lancefield testing.
How does Lancefiled testing work?
Lancefield utilizes C carbohydrate in serum. It is antigenic and can be extracted from the cell walls of strep.
Which streptococci are most likely to be IDed by Lancefiled testing?
beta hemolytic streps (alpha hemolytic streps won't work)
Can S. pneumoniae be identified by the Lancefield test? What about "viridans" streptococci?
No, neither can.

Note: viridans are't a species of strep they are just a classification.
What group does S. Pyogenes belong to?
Group A. Pyogenes means pus
Is group A alpha hemolytic?
No, Group A is beta hemolytic.
What is the confirmatory test for Group A streptococcus?
Bactracin test: almost all are sensitive to low conc. of bactracin. So, if beta hemolytic AND bactracin sensitive--we have a Group A strep= pyogenes
What is the BEST way to test for streptococcus pyogenes?
Lancefield serum test: decect Group A Ag w/ Group A antiserum in precipitin or immunofluorescense tests. Rarely doen b/c of difficulty.
What is the rapid test for Group A strep? What is the sensitivity?
enzyme immunoassay or latex bead aggulutination. Sensitivity is 80%
What is contained in the cell envelope of the S. Pyogenes? 3 important things...
M protein covalently bonded to the peptidoglycan and extends through the carb antigen layer--looks like hair. Also, lipoteichoic acid. And a capsule containing hyaluronic acid.
What type antibodies protect against S. Pyogenes?
anti-M Ab
What is the M protein's function?
antigenicity, antiphagocytic activity, virulence
What determines serogroups? serotypes?
serogroups by lancefield carb Ag. serotypes by M protein Ag.
What types of acid are found in streptococcus pyogenes? Where is it bound? Which acid can be secreted by the cell?
teichoic acid COVALENTLY bound to peptidoglycan and lipoteichoic acid anchored in the cell membrane--can be secreted from the cell.
What can lipotechoic acid bind to?

What proteins are important in adherence.
Lipoteichoic acid binds to M protein, allowing for adherence to the oropharyngeal epithelium via FIBRINECTIN.

F protein is cell surface component that binds fibronectin and important in adherence.
What is the capsule of group A strep made of? Does this provide antigenic properties?
Hyaluronic acid, no antigenic properties b/c it resembles that of human CT. Increases virulence and has antiphgocytic activity.
What is responsible for the red rash of scarlet fever? Where is the gene found?
Strep. pyogenes. An exotoxin AKA erythrogenic toxin.

Gene produced on lysogenic bacteriophage.
When the rash is treated, is the underlying strep infection treated as well?
What exotoxins are produced and what type of antigens are they?
A, B, C are supertoxins
What causes streptococcal toxic shock syndrome?
TSST-1 enterotoxins produce a broad T cell stimulation and CDK expression
What are the two hemolysins produced by streptococcus pyogenes?
streptolysin O and S. O= oxygen and S=serum.
Which groups produce streptolysin O?
Groups A, C, G
How can streptolysin O be determined?
O from ASO (antistreptolysin O) Ab form sera. S from
What is streptolysin S's relationship to oxygen? Where does S produce hemolysis? O?
Stabilized by oxygen. Only grows in presence of inducer like serum. Resistant to oxygen, causes surface hemolysis. O gives hemolgysis deeper in the agar plate.
What type of enzyme is Endotoxin B?
histolytic protease. might cause necrotizing fascitis
Which enzyme converts plaminogen to plasmin? What does this promote?
Streptokinase (fibrolysin) promotes fibrinolysis
Why is DNAase useful?
Can identify streptococcus. Four antigenetically different forms. DNAase AKA streptodornase
Which enzyme is known as spreading factor? Why?
hyaluronidase b/c promotes spread of infection by digesting hyaluroic acid of CT.
What is the relationship between the capsule of S. pyogenes and the hyaluronic acid of CT?
These virulence factors are expressed at different stages of infectous process
WHat is the exception to all secreted products are antigenic?
streptolysin S
How is Group A strep spread?
via asymptomatic nasopharyngeal carriers or by patients w/ pharyngitis
What type of strep infection is common in temperate climates? Tropical?
Temperate--strep sore throat (common in children ) group A, C, G

tropical--pyoderma. preschool kids likely to get it.
What are some suppurative strep pyogenes diseases caused by direct local infection?
upper respiratory infections--tonsilits, sinusitis, otitis media, mastoiditis, meningitis


skin infections (pyoderma)superficial--impetigo; CT--cellulitis, erysipelas, necrotizing fascitis

Bone and joint infections

Postpartum infections--postpartum endometritis and puerperal sepsis

bacteremia and endocardidits. Endocarditis w/ defective heart valve.
What are some suppurative toxin mediated diseases caused by streptococcus?
scarlet fever, strep TSS, necrotizing fascitis or myositis = flesh eating bacteria.
What are some non-suppurative diseases caused by streptococcus? What are these diseases mediated by? What is the treatment?
acute rheumatic fever (ARF) and acute glomerulonephritis (AGN) BOTH ARE IMMUNOLOGICALLY MEDIATED. Treatment of ARF prevented by penicillin to reduce immunogenic stimulus
Which would be more helpful in diagnosis of streptococcus: gram staining for pharyngitis or skin? Why?
pharyngitis in oral cavity where lots of normal flora exist. In skin more infomative b/c not generally present in its normal flora
How is group a streptococcus diagnosed?
determine if beta hemolytic then check for bacitracin sensitivity. Takes a long time though. Usually do a quick test of enzyme immunoassays (Lancefield) or latex bead agglutination
Are serological tests useful in determining recent strep infections?
Yes, use anti-streptolyisn O (ASO)titer. Check for elevation. dx rheumatic fever
What is the Schultz Carlton rxn? The Dick test?
Schultz carlton inject Ab into region of rash suspect of scarlet fever. Localized blanching due to neutralization of toxin.

Dick test--inject toxin in skin to check for immune status. lack of immunity = red. Immunity= no rxn
What is the status of beta hemolysis and bactracin sensitivity in Group B strep? How can these be distinguished from Group A?
weakly beta hemolytic and only 6-20% sensitive to bactracin. Distinguish from group A with ability to hydrolyze sodium hippurate.

OR use the CAMP test to distinguish among other beta hemolytic bacteria. group b will ENHANCE hemolysis of adjacent streps
What diseases do group B streps cause? How are they transmitted? What is group B's species name?
causes neonatal sepsis, meningitis, pneumonia.

Resident flora of vagina, can infect newborns w/ high mortality when passing thru birthcanal. Lowered mortality when transmitted in nursery.

S. agalactiae
What are the characteristics of group C and G streptococci? Where are they found? What diseases can they cause?
Similar to Group A--beta hemolytic, bacitracin sensitive, produce same exotoxins as group A. Found in pharynx, GI, skin normal flora. Cause skin wound infections, pneumonia, puerperal sepsis, bacteremia, endocarditis, meningitis
What does rust colored speutum indicate?
Strep. Pneumonia or pneumonococcus.
How does pneumococcus differ from pyogenes?
few exotoxins produced
Since pneumococcus doesn't produce many exotoxins how does it thrive?
pneumococcus avoids host defenses and multiplies which creates a strong inflammatory rxn.
Besides pneumonia what diseases does pneumococcus cause?
second most common form of meningitis, 1/2 of all otitis media in kids
How does pneumococcus grow? Does it produce spores? Is it motile? Is it capsulated? What type of hemolysis does pneumococcus exhibit?
Gram +, grows as diplococcus or as short chains.

Non sporulating



alpha hemolysis.
What is the difference between smooth and rough pneumococcus?
smooth capsulated

rough uncapsulated
What happens after 48 hrs incubation? 72 hrs? What affect does this have on Gram staining?
48 hrs center of colony collapses due to autolysis.
72 hrs remainder lyses.

Should be gram + bacteria but if not sampled quickly enough will die and appear gram - because of leaky walls.
What type of metabolism does pneumococcus use? Are they faculative like the rest of the streptococci?
Fermentation main product lactic acid. Yes, facultive, but do NOT uses o2 for aerobic growth.
What are their nutritional requirements? What happens if they are dried?
pneumococcus are fastidious and require an enriched culture medium.

When dried they'll die
What is the first step in IDing a pneumococcus? Once that has been determined what tests will verify pneumococcus?
alpha hemolytic. 1) optochin sensitivity, (2) bile solubility, (3) inulin fermentation, (4) quellung reaction, and (5) the mouse virulence test.
How does the optochin sensitity work?
pure culture of alpha hemolytic organism on plate, put optochin impregnated disk on plate and incubate overnight.

If pneumococcus is present then there will be a zone of inhibition around the optochin--no hemolysis.
How does the bile solubility test work?
grow bacteria culture then the test is based upon the presence of an autolytic enzyme in the cell wall of pneumococci.

mixing a 10% solution of deoxycholate with a saline suspension of a viable culture of an a-hemolytic streptococcus.

if positive for pneumococcus suspension will become clear

if it is viridans streptococcus it will remain turbid.

viridans streptococci are not lysed by bile, it does inhibit them from growing.
How can inulin fermentation determine pneumococci?
This plant polysaccharide is degraded and fermented with the production of acid by pneumococci, but not by other streptococci.
how does the Quellung reaction work? Why is it so useful? What indicates a positive response?
useful and rapid method for detecting pneumococci directly in clinical specimens of many different types (e.g. sputum).

Not only are the pneumococci detected and identified, the antigenic type of their capsule is determined.

The test is performed by mixing a loopful of a clinical specimen or a bacterial suspension together with anti-pneumococcal antiserum and methylene blue on a microscope slide and then examining the slide with a microscope using the oil immersion lens.

In a reaction between a pneumococcus and homologous antiserum, the capsule swells and becomes more refractile, making it easier to see.
How does the mouse virulence test work? What are the advantages and disadvantages of this test?
intraperitoneal inoculation of mice with sputum from a patient with pneumonia.

The mouse dies within 16 to 48 hours, and pneumococci are then cultured from the heart blood.

This test is very sensitive; it will detect very small numbers of pneumococci.

However it is time-consuming and expensive, so it is rarely performed now.
How many distinct serotypes of pneumcoccus exist? How can they be serotyped?
83. , each capsule is antigenically different, so pneumococcal isolates can be serotyped according to their immunologic reactivity.
What is the most important virulence factor of the pneumococcus? Why?
The capsule is the most important virulence factor of the pneumococcus, since it allows them to avoid phagocytosis by PMN's.
Which antibodies are protective against infection and are essential for recovery from pneumococcal infection? What kind of immunity do they provide? What is the immunity specific for?
anticapsular antibodies

provide long-lasting immunity

the immunity is strictly type-specific.
Which type pneumoccocal serotypes are most virulent? How many account for what % of infections in US?
Type III. 14 account for 80% of infections in US.
How is the capsular pneumococcal vaccine made?
cocktail of 14 most prevalent serotypes into an anti pneumococcal vaccine in 1977, now up to 23 serotypes in 1983.
What is C substance ? Is it used in Lancefield tests?
a teichoic acid, containing choline phosphate, is a major constituent of cell wall.

It is analogous to, but distinct from, the Lancefield group-specific carbohydrate of beta-hemolytic streptococci (which is not a teichoic acid).
What is M protein antigen? How does it differ from M protein in Group A streptococcus?
As in Group A--ß-hemolytic streptococci, M protein is used for antigenic typing of pneumococcal isolates (in addition to capsular antigen).

the pneumococcal M protein is NOT antiphagocytic and is NOT an important virulence factor.
What type of antigens are C substance and M protein?
Name some extracellular products of pneumococcus. (5)
pneumolysin, purpura-producing principle, neuraminidase, IgA protease, amidase
What does pneumolysin do?
a hemolysin, pneumolysin O, with properties similar to streptolysin O

some evidence that it contributes to the virulence of pneumococci, not absolutely essential.
What does purpura do and where does it come from?
causes purpura and dermal hemorrhage in experimental animals.

It seems to be derived from the cell wall peptidoglycan.
What is neuraminidase active against? What does it do? Is it found in other organisms?
active against glycosyl groups on cell surface glycoproteins

and may play a role in the spread of pneumococci through infected tissues.

This enzyme is also found in other organisms that infect the respiratory tract, for example influenza virus.
Which extracellular enzyme of pneumococcus infects mucosal surfaces and secretes IgA? Where is IgA secreted? What does this enzyme do?
IgA protease. cleaves at the hinge region to prepare for further degradation. Might play a role in pneomococcal virulence.
What is amidase? What does it do?
an autolysin produced by S. pneumoniae.

When the cell lyses it releases components that induce inflammation. This is an important part of the pathogenic process. Causes inflammation due to recogniation by toll receptors
Where does S. pneumoniae live? How does infection occur? How many cases per year? Who is most likely to be affected?
lives in throat and nasopharynx of healthy people.

Infection due to a strain NEW to an individual.

500,000 cases/year

affects mostly kids and elderly
What is the rate of high level resistance? What about combined medium and high resistance? What causes resistance: PBP's or penicillinase? Is it plasmid mediated or choromosomal?
high --0-22%

med and high--33%

PBP's cause--not plasmid oriented. Caused by chromosomal mutation
What diseases are caused by S. Pneumoniae?
- Lobar Pneumonia
- Local Complications (empyema, pericarditis, lung abscesses)
- Bacteremia
- Otitis Media
- Mastoiditis and sinusitis
- Endocarditis
- Septic Arthritis
- Peritonitis
- Conjunctivitis, Corneal Ulcer
- Meningitis
What are the two sub-groups of Group D?
enterococci and non enterococci.
Describe enterococci.
Are they streptococci?
Are they penicillin resistant?
Where are they found?
What diseases can they cause?
Are they Vancomyosin resistant?
very tough organisms: heat resistant, and grow well in media containing 40% bile (bile resistant) and in the presence of 6.5% NaCl.

classified into a new genus Enterococcus, that is separate from the genus Streptococcus.

Enterococci are uniformly penicillin resistant, differing from the other streptococci in this respect.

Enterococci are normal flora in the lower GI tract

relatively common causes of urinary tract infections, wound infections, peritonitis, bacteremias, and endocarditis.

Vancomycin-resistant enterococci is an emerging problem.
What is the differnce between enterococci and non-enterococci?
are penicillin sensitive and cannot grow in 6.5% NaCl
Are non-enterococci classified as Streptococcus? What are two pathologic non-enterococci? Which causes endocarditis?
yes they are

. Two species are S. equinus, which rarely causes human disease, and S. bovis, which is a relatively common cause of endocarditis.
What are characteristics of viridans streptococci? Are they pathogenic? What will kill them? Which is involved in tooth decay?
greenish alpha hemolytic streptococci that cannot be classified by group-specific carbohydrate antigens.

"viridis" which means "green",


normal resident flora in the mouth, oropharynx, and upper respiratory tract. They

will not grow in 6.5% NaCl and are killed by heating at 60_C.

non-pathogenic. Unless get into bloodstream--dental manipulation

S. mutans= plaque, secretes acid inbetween plaque and tooth and leads to decay.
What are the general characteristics of neisseria in terms of motility, spore formation, Gram status and growth pattern.
nonmotile, non-sporeforming, Gram-negative cocci which characteristically occur in pairs (diplococci) with adjacent sides flattened. The kidney-shaped concave sides face each other.
Name some species of Neisseria present in normal flora.
N. lactamica, N. sicca, N. flavescens, N. mucosa, and N. subflava.
What do Nisseria test positive for?
oxidase test due to posessing cytochrome C and catalase positive.
What are 2 pathogenic Nisseria and what is the reservoir?
Neisseria gonorrhoeae and N. meningitidis both have human reservoir only
What type of metabolism do Neisseria gonorrhoeae and N. meningitidis do?
obligate aerobes.
What type of culture do Nisseria grow on?
chocolate agar--bood heated to 80 degrees C. inactivates toxic inhibitors
Are nisseria capnophilic?
somewhat--n gonorrheae more so
Which pathogenic nisseria is more fastidious?
When swab of bacteria is from pharynx, cervix, or rectum what must the agar contain? What is its purpose?
Chocolate agar containing vancomycin, colistin, nystatin, and sometimes trimethoprim (Thayer-Martin medium)

antimicrobial agents that inhibit most normal flora species (including non-pathogenic Neisseria) but that allow gonococci and meningococci to grow.
How is drying sensitivity overcome?
special transport medium containing a source of carbon dioxide (bicarbonate ion) is used to transport culture swabs from the clinic to the laboratory if the cultures are not plated immediately
Where do specimins of gonorrheae and meningitis come from?
In gonorrhea the specimen is typically a swab of a cervical or urethral discharge, while in meningococcal meningitis the specimen would be cerebrospinal fluid.
How are pathogenic nisseria IDed? Initial? Definitive? How can species be determined?
can be directly Gram-stained, and will show numerous polymorphonuclear leukocytes (PMN's or "polys" or neutrophils) many of which will contain Gram-negative diplococci.

Confirm by culture: from CSF grow in culture directly. Gonorrheae usually in Thayer Martin medium

Test for oxidase and catalase positivity.

Then test for species by production of acid from sugars.
N. gonorrhoeae produces acid only from _____ while N. meningitidis produces acid from ____?
N. gonorrhoeae produces acid only from glucose, while N. meningitidis produces acid from BOTH glucose and maltose. The

non-pathogenic Neisseria exhibit other patterns of sugar utilization.
Is there a serologic test for Nisseria pathogens?
Which portion of nisseria meningitidis is antiphagocytic? How is the vaccine made?
Polysaccharide capsule the antigen which is used in the vaccine (a mixture of 4 different serogroup polysaccharides).
What classification does the Neisseria meningitidis endotoxin fall under? What does the toxin cause?
lipo-oligosaccharide (no O Ag)

Causes fever, shock,
Which enzyme is found in Neisseria meningitidis and what does it do? Why?
IgA protease cleaves at hinge. cleaves Fab arms of immunoglobulin A away from the Fc region.

help the bacterium colonize and traverse mucous membranes of the upper respiratory tract.
What are important features of host defense against Neisseria meningitidis?
Capsule-specific antibody, Phagocytes and complement

since people with genetic deficiencies in complement have an increased incidence of meningococcal disease.
What is probably most important in neisseria gonorrhoeae virulence?

What are the two types of variation?

What does this create?
Pili--capable of infecting mucosal surfaces, phase variation--turn pili on and off and antigenic variation of pili--change pilus antigenic type

Stay ahead of immune response. Complicates vaccine efforts. Increases repeat infections w/o immunity
Describe the outer membrane protein, porin. What kind of resistance does it confer?
porin--Protein 1, most abundant, provides channels and allows contact to epithelial cells. Some confer resistance to complement. geneically stable.
What is opa? What is second stage adherence?
outer membrane protein of gonorrheae.

Opacity protein (Opa), also called Protein II.

Subject to phase variation and antigenic variation.

Opa is involved in adherence among gonococcal cells, resulting in the opaque colony type.

Also involved in a second stage of adherence to epithelial cells (after pilus attachment), in which direct cell-to-cell contact occurs.

Different Opa proteins allow adherence to different types of host cells.

Possibly involved in invasiveness as well.
What is protein III? What does it do?
Reduction modifiable protein (Rmp) aquisition of Fe.
What is the endotoxin like?
Like meningitis endotoxin LOS (not LPS)
Is IgA protease found in gonorrhea?
Yes, helps the bacteria colonize in mucous membranes of urethra, vagina, cervix,
What happens if gonorrheae mucosal infection is asymptomatic and untreated?

What are these resistant to? Sensitive to?

What is an important host defense?
enter the bloodstream and cause disseminated infections

resistant to serum (complement), are very sensitive to penicillin, have unusual nutritional requirements, and may be non-piliated.

Phagocytosis is important aspect of host defense against gonococcus.
Which is more likely to be resistant to penicillin: gonorrhea or meningitidis? To sulfonamides?

What is Low-level penicillin resistance due to? What is high-level penicillin resistance due to?
LOW LEVEL--chromosomal mutation (PBP's affected)and does not involve production of penicillinase.

HIGH LEVEL--is plasmid-mediated and is due to penicillinase.
What diseases are caused by meningitidis? Gonorrhoeae?
Neisseria meningitidis

- meningococcal meningitis

- meningococcemia (septicemia)

Neisseria gonorrhoeae

- gonorrhea

- disseminated gonoccocal infection (e.g. septic arthritis)

- ophthalmia neonatorum
What are the general characteristics of Corynebacteria? Gram status, shape, metabolism, flaglla or capsule presence.
gram +, RODS, non-spre, obligate aerobes, club swelling at ends, no flagella or capsule.
What is contained in cell wall of corynebacteria?
mycolic acid.
What is corynebacteria related to?
related to mycobacteria and nocardia, but not acid-fast
Where is corynebacteria found?
in soli, on animals and humans
What sugars cause acid production in C, diptheriae? C xerosis? C. pseudodiphtheriticum?
C. diphtheriae--glucose, maltose, (sucrose--sometimes +)

C. xerosis--glucose, sucrose, and maltose positive.

C. pseudodiphtheriticum--negative glucose, maltose, sucrose
Why is diphtheria rare in the US? What kind of vaccine is available? What causes the diptheria toxin? Where is the toxin located?
rare due to immunization by toxoid vaccine. Key virulence factor is exotoxin

Toxin located on phage
Is Corynebacterium diphtheriae heat labile? What are the fragments of the toxin--which is active?
yes, heat labile. Fragments are released by cleavage of peptide bond between amino acids 194-195.

Fragments A and B attached by disulfide links.

Fragment A is active
What does fragment B do?
B is required for binding of diptheria toxin to its receptor on the cell surface and for translocation of the A fragment across membrane to target cell
How does Fragment a work?
It is an ADP ribosyltransferase [like exotoxin A of Pseudomonas]

It transfers the ADP-ribose portion of NAD to protein synthesis elongation factor EF2

thus irreversibly inhibits protein synthesis and kills the cell
What amount of toxin is needed to produce a rxn in humans? To kill a rabbit?
1/10,000 ug human rxn

at 0.1 ug/kg kills rabbit
What regulates diptheria toxin? What turns it on?
iron concentration

low iron turns it on and high iron turns it off
How is diphtheria toxin converted toxoid?
treatment with formalin at 37 degrees C.
How is diphtheria spread? Where does infectin begin? Multiply? What happens to neighboring cells?
spread by aerosols and respiratory dropletes, infection begins in respiratory tract, multiply in throat mucosa.

Kills neighboring cells.
What does tissue damage and inflammation result in?
an exudate which forms a grayish pseudomembrane on tonsils and pharynx, spreading to nasal passages or larynx. Pseudomembrane aspiration or laryngeal diphtheria may result in suffocation.
Do organisms cause bacteremia in diphtheria?
No...lymph nodes may enlarge, but bacteria are confined to throat mucosa, won't cause a systemic infection
What are some effects of diphtheria?
moderate fever

late cardiac, neurologic, renal complications due to damage by circulating toxin
Can diphtheria cause skin leasions?
Yes, sometimes in conjunction w/ other bacteria like S. aureus.
What test determines immune status? (rare in US)
Schick test--inject small quantity in one arm, toxoid in the other. Absence= circulating antitoxin protection

Positive w/in 5 days shows not immune
How are specimens of diphtheria taken?
swabs of nose and throat.

stained w/ gram or methylene blue.

culture on blood agar, 37C, Loefflers slant, tellurite agar plate (colonies black or grey.)
What are the three possible colony types on tellurite agar? Which is pathogenic?
gravis--large, flat, grey/black, dull

mitis (medium size, black, glossy, more convex)

intermedius (very small, can be smooth or rough)

All are pathogenic
What is the Elek Immunodiffusion test?
For identification of toxigenic isolates

A filter paper strip saturated with antitoxin is placed on an agar plate.

The suspected culture is heavily streaked in a line perpendicular to the filter paper strip, and the plate is incubated.

A toxigenic strain will produce a precipitin line composed of toxin-antitoxin immune complexes at a 45 degree angle between the filter paper strip and the line of bacterial growth after 24 to 48 hours.
What therapy is available to treat diphtheria?
antitoxin (vaccine) very good.

If infected use antibiotic to eliminate organisms (don't use vaccine here--already compromised)
When should people be vaccinated against diphtheria?
get dpt at 6-8 wks, get first of 4 doses before age 4 and a booster before school starts. Booster every 10 yrs for Td.
Which is most important listeria?
L. monocytogenes
What are general characteristics of L. monocytogenes?

How and where do they attach?
short rod, gram +, in pairs or chains

attach to intestinal epithelial by listeria adhesin (internalin) bound to E cadherin
How do L. monocytogenes use oxygen?
faculative, grow best in 5-10% CO2, capnophilic
Do L. monocytogenes form spores and capsules? What type of hemolysis do they exhibit?
Non-sporeforming; no capsule

weak beta hemolysis on blood agar due to action of listeriolysin.
What are Listeria monocytogenes related to?
Where are Listeria monocytogenes found?

Where are they found in the food industry and why?
worldwide, in soil, domestic and wild animals.

Frequent infection from milk, cheese, processed meat.

Very hardy not killed by heat.
Who gets infected? What type of pathogen is Listeria monocytogenes?
opportunistic pathogen. pregnant women and immunocompromised people are affected.
What types of perinatal listeriosis occurs? Why are they caused?
Early onset: Sepsis and death before or after delivery.

Late onset: Meningitis (between birth and 3 weeks); high mortality; third most frequent cause of neonatal bacterial meningitis.

Both of these may be the result of intrauterine infection.
What diseases occur b/c of adult listeriosis?

How is infection transmitted?

Does everyone who carries listeria get sick?
meningoencephalitis and bactermia and septicemia.

Route of infection is uncertain, but association of infection with various foods (e.g. unpasteurized milk or cheese) indicates that infection is via gastrointestinal tract.

In some pregnant women or in otherwise healthy people Listeria can occasionally cause a mild flu-like illness, but asymptomatic carriage is more common.
What is characteristic of a lab diagnosis of listeria?
get organisms from blood and CSF. Small zone of hemolysis on blood agar.

What are general characteristics of erysipelothrix?
resembles listeria BUT NON-MOTILE!!


smooth--short chains
rough--long filaments

world wide--ESP IN SWINE
What does erysipelothrix look like clinically?

How is it contracted?
usually in skin, pain, pruritis, edema, purple lesions w/ sharp margins and clear centers. No fever, common relapses

aquired thru lesions in skin following handling of fish, shellfish, meat, poultry.
What causes erysipeloid? Erysipelas?
erysipeloid --E. rhusiopathiae,

a similar disease in humans called erysipelas is caused by Group A beta-hemolytic Streptococcus
How is Erysipelothrix rhusiopathiae determined in the lab? What is it resistant to?
Isolation of organisms from biopsy of skin lesions on blood agar. Weakly hemolytic.

**Resistant to neomycin (unlike Listeria).
What are the characteristics of Bacillus?
aerobic spore formers. Most species are non-pathogenic soil or environmental organisms.
What are 2 pathogenic species of Bacillus?
B. anthracis, which causes anthrax

B. cereus, which is one of the causes of food poisoning.
What does B cereus produce that causes food poisioning? What do they cause? What foods are specific to each?

In additon to food poisioning what else can B. Cereus cause?
(1) emetic (vomiting) form, due to heat-stable enterotoxin, caused by contaminated rice

(2) diarrheal form, due to heat-labile enterotoxin. Caused by contaminated meat and vegetables. Longer incubation period.

B. Cereus causes eye infection--panophthalmitis
Who does anthrax infect?

Is anthrax more lethal if inhaled/ingested or thru skin lesions?
Usually animals. Humans can get it thru contact w/ wool and hides of infected animals.

fatal if untreated.

inhaled or ingested more dangerous than thru skin lesions.
What are the characteristics of clostridium?
gram +, spore forming, obligate ANaerobes, many important pathogens
What are the characteristics of gardnerella?
Gram variable, vacterial vaginosis, clue cells present
What are the characteristics of lactobacillus? Where are they found? What use might they have?
Normal flora in mouth, bowel, vagina. Non-pathogenic.

Used in production of fermented foods, such as yogurt, sauerkraut, sourdough bread, and may be present in them.

investigated as probiotics, bacteria which can be intentionally implanted as components of normal bowel or urogenital flora for the purpose of competing with and excluding pathogenic bacteria.
Which large heterogeneous group of Gram-negative bacteria are among the most medically important organisms, capable of causing infection essentially anywhere in the body, given the right circumstances.
What is nosicomial?
hospital acquired
What are the fecal coliform bacteria?
E. coli, Klebsiella, Citrobacter, and Enterobacter
Is it possible to generalize virulence of enterobacteria?
often not possible to generalize about how virulent they are

Different strains of a single species can vary widely in their virulence.
Is enterobacteriaceae gram + or -?

Aerobic or Anaerobic?

Spore forming?


What sugars does it ferment?
Gram -



does not form spores

both motile and non motile species (peritrichous--multiple flagella for those that are motile)

Ferment glucose (distinguishing characteristic is inability to ferment lactose)
Are Enterobacteriaceae oxidase positive or negative?

Do they reduce nitrate?

Do they have pili?

What type of toxin do they posess?
oxidase negative

reduce nitrate to nitrite

Have pili, important in antibiotic resistance. Also have adhesive pili--adhesins

LPS enodtoxin (in all gram - bacteria and listeria monocytogenes--gram +)
What are the 3 types of surface antigens and what are they used for?
O, H, K

used for ID
What does the O antigen do?
Part of outer membrane, part of LPS.

the endotoxin activates clotting pathway, alternate complement pathyway, interacts with cells of the immune system (macrophages and B cells)

cause fever (endogenous pyrogens)

increase vascular permeability (hypotension)

fibrinogen clotting cascade = disseminated intravascular coagulation (DIC)
What are characteristics of endotoxin-mediated toxicity?
1. fever

2. leukopenia, followed by leukocytosis

3. activation of complement

4. thrombocytopenia

5. disseminated intravascular coagulation

6. decreased peripheral circulation and perfusion to major organs

7. shock, and ultimately death
How can endotoxins be released?
component of the bacterial cell, but it can be released from the cell

1. when the cell lyses and disintegrates or

2. by the formation of blebs which bud off from the outer membrane.
What are the three components of a lipopolysaccharide molecule?

Which portion provides antigenicity?
1. lipid A, which is the toxic and physiologically active part of LPS

2. R core, a short non-repeating oligosaccharide

3. O antigen, a long repeating polysaccharide.

O antigen provides antigencity and many bacteria are assigned #'s due to this
What are antisera specific Ags used for?
Antisera specific for each different O antigen type are used as reagents in the serological typing reactions, which are performed as agglutination reactions on heat-killed bacterial cells.
What are smooth O antigens?
Bacteria containing full-length O antigen are referred to as smooth, which is a description of their colony morphology.

Mutants which have lost their ability to produce O antigen but retain R core are called "rough".
Where is the H antigen found?

What is it made of?

Heat labile or stable?
The H antigen is the bacterial flagellum.

protein subunits called flagellin, and is therefore heat labile.
What preserves labile falgellar antigens?
Formaldehyde treatment preserves the labile flagellar antigens,

and cells are agglutinated by specific anti-flagellar (anti-H) antibodies, forming a light, fluffy clumping.
What is antigenic variation and which antigen possess this?
Some strains can switch back and forth between two or more H antigen types by a special genetic mechanism called antigenic variation.
Do H Ags differ between species?
Different H antigen types (H1, H2, etc.) can exist within a bacterial species.
Where is the K Ag found?

What is it made of ?

Heat labile or stable?

What do the Vi Ag and K1 Ag belong do?
The K antigen is the bacterial capsule,

typically consists of polysaccharides. It is partially stable to heat.

Vi antigen of Salmonella typhi and

the K1 antigen of E. coli.
Which Enteric genera affects the following?


Respiratory tract?




Central nervous system - Escherichia

Lower respiratory tract - Klebsiella, Enterobacter, Escherichia

Bloodstream - Escherichia, Klebsiella, Enterobacter, Salmonella

Gastrointestinal - Salmonella, Shigella, Yersinia, Escherichia

Urinary tract - Escherichia, Proteus, Providencia, Klebsiella

Bones - Salmonella
Is E coli motile?

How many genes in e coli?

Where is E coli commonly found?
Usually motile

4300 genes

intestinal tract of humans and animals
What infections does e coli cause?
some of the most common bacterial infections:

-urinary tract infections
- bacteremia and septicemia
-neonatal meningitis
-wound infections
-variety of gastrointestinal infections, including traveler's diarrhea.
What are most E. Coli infections caused by?
Most E. coli infections (with the exception of gastroenteritis) are caused by endogenous gut flora.
What is the Antigen composition of E. Coli like?
different strains having more than 170 O antigens, 56 H antigens, and 100 K antigens. Individual strains are named by their combination of O and H (and sometimes K) antigens, for example, O157:H7.
What do uropathogenic strains of E Coli possess?
(UTIs)Uropathogenic strains of E. coli possess :
--P pili (adhesins),
--ability to resist complement-mediated killing.
What is septicemia commonly associtated with?
UTI more so than GI disease
Nearly 75% of neonatal meningitis causing E. coli strains possess which antigen.
the K1 capsular antigen.
How is an abdmonial abscess formed?
What type of bacteria are usually involved?
colon contents escape from the bowel lumen into the peritoneum through a perforated diverticulum or other bowel perforation they can cause an abdominal abscess or peritonitis.

mixed infections

involving both facultative and anaerobic bacteria, and E. coli is frequently involved.
What are the 2 categories of diarrheal diseases?

What is the difference between the two?
secretory and dysentery diarrhea

(1) secretory diarrhea with a high volume of watery stools, little or no fever, and absence of blood in stools

(2) dysentery, with a low volume of stools containing blood, mucus, and sometimes pus, high fever, and straining and painful defecation.
What are the 5 different types of diarrheagenic E. coli strains causing intestinal infection?
1. (ETEC)Enterotoxigenic E coli

2. (EPEC)Enteropathogenic E coli

3. (EAggEC)Enteroaggregative E coli or(DAEC) Diffuse adherence E. Coli

4. (EHEC)Enterohemorrhagic E coli

5. (EIEC) Enteroinvasive E coli
What is ETEC caused by? Describe the process of each.

What problem does this often cause and what are the symptoms?
to two exotoxins: a heat-labile toxin and a heat-stable toxin.

The heat-labile toxin activates adenylate cyclase, resulting in hypersecretion of fluids and electrolytes into the lumen of the small intestine. This mechanism is similar to that of the Vibrio cholerae enterotoxin.

The heat-stable toxin activates guanylate cyclase, and it too stimulates fluid secretion.

ETEC are an important cause of traveler's diarrhea. This infection of the small intestine has a 1-to 2-day incubation period and persists for an average of 3 to 4 days. Symptoms are mild, with watery, non-bloody diarrhea, cramps, nausea, and vomiting most commonly experienced.
Where do EPEC act?

What is a defining characteristic?

What symptoms do they cause?
site of infection is the small intestine, where they adhere to the mucosal epithelium in a focal pattern ("localized adherence"), forming piled-up three-dimensional microcolonies. They produce characteristic "attaching and effacing lesions" on the mucosa of the small intestine with destruction of microvilli and "intimate" attachment to cell membrane at sites of "pedestal" formation.

include fever, nausea, vomiting, and non-bloody stools.
Who does EAggEC affect most?

What are symptoms?

What is defining characteristic?
Affects small intestine, causing persistent diarrhea in infants.

Low grade fever, sometimes bloody stools.

adhere to gut epithelial cells in an aggregative manner, with formation of single-layered 2D ARRAYS!!!!!of bacterial cells resembling "stacked bricks" lying flat on the epithelial surface. Another pattern of adherence that is seen is called diffuse adherence,
Where do EIEC act?

what disease does this resemble?

What are symptoms?
invade and destroy the epithelium of the large intestin

Bacillary dysentery (shigellosis)

Fever bloody diarrhea (rare in US)
What does EHEC produce?

What are the symptoms?

What causes outbreaks?
cytotoxin called verotoxin, and a are not invasive

majority of cases have mild diarrhea, but in a fraction of cases this organism causes hemorrhagic colitis, with severe abdominal pain, and bloody diarrhea with little or no fever.

Outbreaks of EHEC hemorrhagic colitis transmitted in undercooked ground beef in fast food restaurants often involve strains of antigenic type O157:H7.
What is an uncommon, but serious complication of EHEC?

Can bacteria be found in the blood?
hemolytic-uremic syndrome (HUS) in infants and young children.

cannot determine bacteria from blood
Are these diarrheagenic strains of E. coli will usually be lactose positive or negative?
All are positive, makes it difficult to determine which type.
Is Klebsiella motile?

Does it have a capsule?

Ferment lactose?

Most common member? What does it cause?


lactose fermenting

Klebsiella pneumoniae (affects alchoholics, diabetics, other comprised hosts)

causes wound, soft tissue, UTI

Ferment lactose?

What type of pathogen?

Who do they infect?

What infections does it cause?
motile and lactose fermenters.

weak opportunistic pathogens that rarely cause human disease.

usually infect hospitalized patients, particularly those who have been treated with antibiotics.

Enterobacter has been associated with burn, wound, respiratory, and urinary tract infections.
Do Serratia ferment lacotose?

Are they motile?

Which is pathogenic? What does it produce?

Who is infected?

Where are outbreaks common?

What types of infections are caused?
motile organisms which ferment lactose slowly, if at all.

Only Serratia marcescens has been routinely associated with human disease.

Some strains produce a red pigment, prodigiosin.

Serratia are mostly involved in hospital patients with debilitating disorders, under treatment with broad-spectrum antibiotics and subjected to instrumentation or catheterization.

Outbreaks have occurred in nurseries, intensive care units, and renal dialysis units.

Serratia can cause respiratory tract infections, UTI, osteomyelitis, and wound infections.
Does Proteus produce lactose?

Are they motile?

What do they produce? What does this cause?

What type of infections does it cause?

Which member is of interest? Why?

--non-lactose fermenting

--motile organisms.Some species of this genus are so hyper-motile that they can travel over the surface of an agar plate. Thus they do not remain in place to form isolated colonies. Instead, they swarm across the surface of the agar. Areas of growth consist of concentric circles of a thin film of bacteria, due to the cyclic re-appearance of highly motile bacteria when the nutrients in the occupied part of the plate are exhausted.

--unusual in being able to deaminate phenylalanine and lysine.

--Proteus strains produce large amounts of the enzyme urease which cleaves urea into carbon dioxide and ammonia.

--This raises the pH of urine and favors the formation of certain renal stones.

--The most common site of Proteus infections is the urinary tract.

--The antigenic structure of P. vulgaris is of particular medical interest because strains possessing certain O antigens (OX2, OX19, OXK) are agglutinated by the serum of patients with various rickettsial diseases (Weil-Felix reaction).

--These particular O antigens seem to be related to certain epitopes present on the rickettsiae.
Which member of Yersina is the most important pathogen? What does it cause?

Which one causes enterocolitis?

What is the source of infection?

What can this disease look like?

What can the bacterium cause?

Which member is an uncommon cause of disease?
pathogen = Y. pestis

--causes plague.

--Yersinia enterocolitica causes enterocolitis, and is associated with cold climates and the winter season.

--Source of infection may be contaminated meat or milk.

--Disease can mimic acute appendicitis. This bacterium also occasionally causes transfusion-associated bacteremia or septicemia.

--Yersinia pseudotuberculosis is an uncommon cause of human disease.