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198 Cards in this Set
- Front
- Back
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Colonization
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growth of benign, non-pathogenic organisms in a host
-oral and intestinal cavities -health depends on this homeostasis |
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infection
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growth of potentially pathogenic organsims in the host w/o disease
-can imply carrier |
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disease
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growth of pathogen with adverse effects on the host
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Anciently what was thought to cause disease?
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-supernatural acts such as voodoo
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Fracastorius's work
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proposed that some diseases were spread from person to person by direct contact, contaminated objects and through the air
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Antonie Van Leewenhoek's work
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recorded microscopic observations of bacteria, fungi, and protozoans
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Pasteur's work
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spontaneous generation discreditation
-developed first attenuated vaccine against anthrax and rabies -pasturization process |
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explain spontaneous generation
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-non-living objects can give rise to living organisms
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What year was the Golden Age of Bacteriology and what were the main discoveries
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1800s
-germ theory of disease -many pathogenic m.o.s discovered |
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how was the anthrax vaccine developed?
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-discovered through mutations
-rough strain w/o capsule was avirulent |
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Robert Koch's work
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-developed methods of isolation/cultures
-1st agar and staining methods -koch's postulates -steam = steralization |
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Koch's postulated establish what
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criteria used to establish a relationship b/w pathogen and disease
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Koch's 1st postulate
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organisms must be found in the diseased animal, but not in a healthy one
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Koch's 2nd postulate
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the organism must be isolated from diseased animal and grown in a pure culture in vitro
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Koch's 3rd postulate
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isolated organism must reproduce the disease when introduced to a healthy organism
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Koch's 4th postulate
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organism should be re-isolated from experimentally infected animal
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What are some exceptions to Koch's postulates?
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-syphillis cant be grown in a lab
-some pathogens are human only so unethical to re-infect a human |
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Joseph Lister's work
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-doubted sepsis cause was from O2 exposure
-1st to cleanse wounds with carbolic acid solution |
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Top 3 killing diseases
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1. acute respiratory infections
2. diarrheal diseases 3. TB |
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Significance of E. coli 0157:H7 serotype
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-one cell = disease
-zero tolerance in the US -Bloody diarrhea and hemolytic renal syndrome |
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Hemolytic renal syndrome (HUS)
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-intravascular coagulation
-fibers bind up -extremities turn black -kidney failure -no treatment methods |
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Nosocomial infections
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-hospital acquired
-usually antibiotic resistant |
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What are some of the causes of new emerging infectious diseases
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-complex process of aquiring new DNA
-cross in taxonomic lines (viruses w/ bacteria) -Human factors and technologies |
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Why is it important to recongize the difference b/w prokaryotic and eukaryotic cells w/ treatment options
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-selective toxicity
-want to kill pathogen and not harm the host |
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Eukaryotic cell differences
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-larger
-nuclear membrane -diploid DNA -mitocondria = respiration -Golgi and ER -No cell wall -sexual and asexual reproduction -complex flagellum |
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Prokaryotic cell differences
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-smaller
-no nuclear membrane -haploid DNA -cellular membrane = respiration -Ribosomes w/i cytoplasm -peptidoglycan -asexual reproduction -simple flagellum |
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peptidoglycan
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-membrane of bacteria
-rigid cell wall -protects from osmotic lysis |
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Two examples of bacteria with irregular shapes
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-bacteroids
-mycoplasmas |
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Capsule
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-external gel material encoating the bacteria
-polysaccharide composition -antiphagocytic functions -adherence functions |
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Key facts about the gram stain
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-most important technique for id
1. crystal violet 2. grams iodine 3. alcohol - decolorize 4. safranin |
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What aspects can cause a bacteria to be gram variable?
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old age
antimicrobials improper decolorization |
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Gram postive =
-structure that constitutes this |
purple
-thick peptidoglycan that doesn't decolorize well |
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What two acids are unique to gram positive wall
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-teichoic
-lipoteichoic |
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Gram negative =
-structure that constitutes this |
pink
-LPS that is easily decolorized |
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LPS =
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lipopolysaccharides
-endotoxin -recognized by host |
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The divisions of a gram-negative cell wall
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1. inner = cytoplasmic membrane
2. intermediate = periplasm 3. outer = LPS |
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Chemical composition of peptidoglycan
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-polysaccharide chains
-altering units of NAG and NAM -joined by a beta 1-4 linkage |
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NAG =
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N-Acetylglucosamine
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NAM =
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N-Acetyl muramic acid
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Differences in gram + and gram - peptidoglycan
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-number of cross links between strings of polysaccharide chains
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Gram positive vs gram negative crosslink patterns
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+ = extra peptide added to tetrapeptide between and frequent crosslinks
- = less frequent crosslinks |
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What structure of gram negative bacteria is primarly responsible to disease
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lipopolysaccahride = endotoxin
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Chemical composition of LPS
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1. Lipid A
2. Polysaccharide core 3. O antigen side chain |
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Lipid A composition
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disaccharide joined by a phosphodiester bond
-long chains of fatty acids -Little variablity b/w bacteria |
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Polysaccharide core composition
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sugars
-heptose -ketodeoxyoctanoic acid -little variablity |
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O antigen side chain
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-repeating subunits of different sugars
-lots of variation b/w bacteria -portion antibodies form from |
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Lipoprotiens
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-gram negative
-anchors outer membrane and peptidoglycan |
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periplasm
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-area b/w cytoplasmic membrane and outer membrane
-peptidoglycan present |
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Bayers Junctions or Adhesion sites
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-binds outer membrane to cytoplasm membrane
-possible function in excretement |
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Gram positive membrane characteristics
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-thick peptidoglycan
-no outer membrane -no lps/endotoxin -teichoic and lipoteichoic acids |
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gram negative membrane characteristics
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-thin peptidoglycan layer
-no teichoic or lipoteichoic acids -outer membrane present -lps present -periplasm -adhesion sites and lipoprotiens |
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Cytoplasmic membranes
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-similar for both
-semi-permuable -site for respirtation -essential protien location |
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Characteristics of bacterial genome
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-hapliod
-supercoiled -circular -structure = nucleoid |
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Two exceptions to the normal bacterial genome
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-Cholerae is diploid
-Borrelia is linear |
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Two types of extrachromosomal elements bacteria can have
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-bacteriophages
-plasmids |
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Characteristics of extrachromosomal elements
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-commonly include genes for adaptive function or pathogentics factors (ie resistant to antibiotics)
-transmitted b/w bacteria -if lost doesn't affect bacterias normal function |
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Bacterial ribosomes structure and function
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-structure = RNA and protiens 30S + 50S = 70S
-site fro mRNA translation and protien synthesis |
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Flagella structure and funtion
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structure = helically coiled protiens in subunits called flagellin
-motility |
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different placements of the flagella
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-peritrichous = all over
-monotrichous = one at pole -lopotrichous = multiple at pole |
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What protien inhibits flagella production
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CAP
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Counterclockwise rotation of flagella =
Clockwise rotation of flagella = |
-straight line motion (a run)
-disorganization (random tumble) |
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Chemotaxis
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movement of bacteria toward nutrients + and away from toxins -
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Describe E. coli as an example of chemotaxis
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-During UTI, E. coli swims toward an AA w/i the bladder
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What role does extracellular protien secretion play for pathogenic bacteria
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-secretes toxins, proteases, flagellar and pilin subunits
-Gram + = 3 systems -Gram - = 6 systems |
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Describe the function of type 3 pathway for E. coli
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-system injects into the host cell
-actin w/i the host cells produces a pedestal for the E. coli to sit on |
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Function of Spirochetes and axial filaments
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-motion for spiral organisms
-endoflagella down periplasma -creates a corkscrew motion |
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Pili or Fimbriae
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-protien subunits pilin
-hairlike structures on the outside of the bacteria |
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functions of the pili
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-adhesion to host of another bacterium
-gliding motility |
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Pili expression is controled by what type of expression
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phase switching
-can be turned on or off |
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composition of endospores
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-resistant to drying, heat and disinfection
-No H2O and dipicolinic acid instead |
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common species with endospores
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bacillus and clostridium
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Metabolism: Prokayotic vs Eukaryotic cells
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-cell division is faster for prokaryotics
-prokaryotic use a more diverse energy supply -make different end products |
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Minimal requirements for growth of bacteria
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-carbon
-nitrogen -H2O -ions --> specifically iron |
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catabolism
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-break down of substrates to a usable energy
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bacteria catabolism includes
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protiens, polysaccahrides, and lipids
-different bacteria focus on different things |
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Fermentation
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-one metabolic pathway
-anaerobic process -not as efficient as respiration -produces end products that are useful in iding the organism |
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intermediate metabolism
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catabolism + anabolism
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Aerobes
Anaerobes Facultative |
-bacteria that grow only in the presence of oxygen
-only grow w/o oxygen -with or without oxygen |
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What can we do to produce anaerobic environments?
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tents and jars
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Fermentation breaks down
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glucose to pyruvate to energy + acids + alcohols
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Selective vs differential media
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selective = only grows certain organisms
differential = tells two apart |
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characteristics of macromolecule biosynthesis
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-transcription and translation are coupled
-mRNA is polycistronic -splicing doesn't occur -there are rare modifications -rapid decay of mRNA |
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Peptidoglycan synthesis occurs in what three areas?
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inside, membrane, outside
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describe the bacterial chromosome
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-haploid
-circular -6 megabases --> 1-9*10^6 base pairs |
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T or F
alterations to DNA can cause genotypic and phenotypic changes in the organism |
True
things like replacements, deletions, insertions, duplications, and inversions |
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Describe direct selection
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-if mutants are beneficial, they are said to be directly selected because they enhance the fitness of the organism
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characteristics of gene exchange and recombination
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-unidirectional
-temporary diploid until substitutions occur followed by cell division |
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merozygotes or merodiploids
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-temporary diploids creates after genetic exchanges occur and before substitution and cell division
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Methods in which DNA is incorporated into the host chromosome
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1. homologous recombination
2. illegitimate recombination 3. site-specific recombination |
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homologous recombination
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donor and recipient have sections of base pairs that are homologous and can pair up.
-the varied center regions can then substitute one another |
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illegitimate recombination
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-donor dna is randomly inserted in to recipient dna
-enzyme = transposases |
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site-specific recombination
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donor DNA again inserts into recipient DNA, but is not random
-occurs in similar sites each time |
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what is an example of site-specific recombination
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phage lambda ecoli
-b/w bio and gal genes |
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Three types of gene transfer
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1. transformation
2. transduction 3. conjugation |
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transformation
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uptake of free DNA in the medium by a competent recipient cell
-complexes on surfaces that allow trasport across the cell wall and into the cytoplasm |
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What strain of E. coli was manipulated to undergo transformation
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K-12 E. coli
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what is the newest method of inducing transformation
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electroporation
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what bacterium is naturally competent for transformation
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gonorrhoea
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explain the Griffith experiment
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pneumococcus to demonstrate some sort of DNA movement
-smooth virulent killed mice -heat killed smoot live mice -rough + heat killed smooth killed mice -rough live mice |
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Avery discovered what after the griffith experiment
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-DNA that caused griffith results
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transduction
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-lederberg and zinder
-bacterial virus as an intermediate taking donor DNA to recipient |
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Divisions amoung bacteriophages
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-shape
-DNA or RNA based -Lytic or lysogenic lifestyle |
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Lytic cycle characteristics
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nontemperate
-virus replicates and bacterial dna is chopped up |
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Describe the Lytic cycle
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1. phage attachment
2. phage DNA enters 3. Phage DNA replicates and bacterial DNA is chopped up 4. Phage assembles 5. Cell lysis |
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Lysogenic cycle characteristics
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temperate
prophage is created |
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describe the lysogenic cycle
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1. phage attachment
2. phage DNA enter 3. phage DNA integrates to form prophage 4. replication occurs and DNA is passed to daughter cell 5. Eventually enters lytic and phage DNA is excised |
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Factors that can cause lysogenic to enter lytic
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-failure to repress lytic gene
-environmental factors |
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What structure mediates bacteriophage attack?
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ligand-receptor relationship
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generalized transduction
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-pieces of the host chromosomal DNA is incorporated into the head of a newly forming phage
-new host phage is then able to infect new recipient cell |
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specialized transduction
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-phage DNA enters to create prophage
-when lysogenic cell switches to lytic, the viral DNA is improperly excised and includes some of the hosts DNA -viral + host creates phage -infects new cell at specific sites w/i new recipient cell |
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lysogenic conversion
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important virulence gene is encoded on a temperate bacterial phage
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example of lysogenic conversion
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diphtheria toxin gene is present on the genome of a temperate virus called the beta-phage
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conjugation
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cell to cell contact b/w donor and recipient
-usually amoung closely related species |
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plasmid mediated traits include
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-antibiotic resistence
-conjugal proficiency -heavy metal resistance -toxins -adherence factors -cellualar invasion factors -unique catabolic functions |
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T or F
It is possible for a bacteria to have multiple plasmids |
True
E. coli has up to 12 |
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transpositions
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movement of genetic material w/i a bacterial cell
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two types of transposition
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1. replicative
2. conservation |
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replicative transpostion
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1. copy created
2. one copy inserts itself at a new site that is usually on a different piece of DNA present w/i the bacteria |
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conservative transpostion
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resident transposon is excised and inserted to a new site
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characteristics of transposition elements
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-range in size
-termini are inverted repeated sequences |
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Classes of these transposition elements
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1. IS elements
2. transpoons 3. conjugative transposons 4. bacteriophages |
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IS elements
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transposition element that encode no function other than transposase
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Transposons
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encode for additional functions
ex: antibiotic ressistence |
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conjugative transposons
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expection to the rule
-movement to another cell via conjugation |
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bacteriophages
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able to integrate randomly
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pathogenicity islands
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entire group of genes that codes for a virulence factor
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Sterilization
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complete killing or removal of all living organisms
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pasteurization
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-not a sterilization process
-heating material to a temperature b/w 55-75 degrees celcius which reduces the number of pathogenic mos |
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Killing is proportional to ______.
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time
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methods for sterilization
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-moist-heat with pressure
-ethylene oxide gas -ultraviolent light -ionizing radiation -filtration |
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surfacent
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soap with the ability to metabolize membranes
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disinfectants
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agent used to reduce number of mos on inanimate objects
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antiseptic
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agent used to reduce number of mos on living tissue
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Describe the effects of refrigeration and freezing on bacteria growth
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-freezing can kill some bacteria
-refrigeration ususally stops the growth of the organism exception = listeria |
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List the most resistant to the least reisitant bacteria
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-Prions
-bacterial spores -mycobacterium -nonlipid small viruses -lipid medium viruses -vegitative bacteria -fungi |
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Who discovered penicillin and how
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Sir Alexander Fleming
-acidental growth on a plate that inhibited the growth of staphylococcus |
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lysozyme
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-cleaves peptioglycan
-found in tears and other mucosal membranes |
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antimetabolite
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a substance that competes with, antagonizes, or replaces a metabolite
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antibiotic
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a substance derived from a fungus or bacterium that inhibits the growth of another microorganism
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antibiotic specrum
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range of activity of a compound against mos
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broad specrum vs narrow specrum
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-broad = drug can inhibit a wide variety of both gram + and gram - organisms
-narrow = active against a narrow group of organisms |
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Minimal Inhibitory Concentration MIC
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lowest concentration of an antimicrobial necessary to stop growth, typically in a laboratory condition
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bactericidal activity
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ability of a chemotherepeutic agent to kill a mo
-expressed as minimun bactericidal concentration |
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combination therapy
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conbinations of antibiotics used to:
-broaden the antibacterial spectrum in mixed infections -to prevent the emergence of resistant organisms during therapy -synergistic killing effect |
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Antibiotic synergy
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combinations of two antibiotics that have enhanced bactericidal activity when tested together compared with each alone
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What are the main antibiotics that inhibit cell wall synthesis
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-penicillins
-cephalosporins -beta-lactamase inhibitors -vancomycin -bacitracin |
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give an example of a beta-lacatmase inhibitor and describe its function
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-clavulanic acid
-inhibits the bacterial destruction of beta-lactam drugs ex: penicillin |
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describe how vancomycin inhibits cell wall synthesis
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-binds D-ala D-ala portion of the peptidoglycan subunit blocking the donation of the subunit to growing chain of peptidoglycan
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Describe how bacitracin works
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inhibits the dephosphorylation of bactreprenol needed for cycling the peptidoglycan subunits from inside to outside of the membrane
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Drugs responsible for the inhibition of protien synthesis
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-aminoglycosides (streptomycin)
-tetracyclines -chloramphenical -macrolides (erythromycin) -lincosmaides (clindamycin) |
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antimetabolites affecting folic acid synthesis
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-sulfonamides
-trimethoprim |
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inhibition of RNA synthesis
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Rifampin
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inhibition of DNA synthesis
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Quinolones
-ciprofloxacin -nalidixic acid |
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Inhibition of DNA function
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metronidzaole (Flagyl)
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alteration of cell membrane function
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polymyxin--> detergent
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How can antibiotic resistance occur?
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-destruction of antibiotic
-failure to bind to the target protien -failure to get to the target protien -modifications of an antibiotics -antibiotic is pumped out of the cell -enzymatic modification of the antibiotic target |
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Where do genes for antibiotic resistance come from?
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-soil organisms is the most common
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Forms of light microscopy
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-Bright-field microscopy
-Dark-field microscopy -Fluorescent microscopy |
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Bright feild microscopy
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-light is directly focused on the mo
-stains are often necessary for visualization and differentiation of cells |
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Two colight mmon types of stains
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-gram stain
-acid fast stain |
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What common organism must be acid fast stained in order to be visualized
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TB
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Dark field microscopy
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-light is brought in from the side
-organism can then be seen against a dark contrast |
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Fluorescense microscopy
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-similar to dark field, but UV light is focused on the object
-object is stained with compounds that are capable of fluorescense |
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T or F
There is no single, universal nutrient medium that can fulfill the requirements for all organisms |
true
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Selective media
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enriches or permits only the growth of the pathogen
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differental media
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distinguishes one bacteria strain from another
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Steps for classical bacterial identification
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1. obtain a pure culture by single colony isolation
2. determine cellular morphology, colonial morphology, and gram stain 3. carry out phenotypic tests |
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What are some examples of phenotypic tests
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-selective vs differental media growth
-biochemical tests -antibacterial sensitivity -antigentic traits |
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What are the genotypic tests
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-based on nucleic acid hybridization
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What tests are used to detect antimicrobial antibodies in a patient's serum
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-agglutination
-immunofluorescence -enzyme-immunoassay -western blotting |
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explain the agglutination reaction
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-suspension of bacterial cells clot in the presence of antibodies specific for that cell
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Immuno or Western Blotting
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1. protiens are seperated by electrophorisis
2. seperated protiens are transfered to a filter 3. protiens are labled with an antibody 4. detect where antibody went and find protien of interest |
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What are hybridization probes?
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Small nucleic acid sequences used to detect specific DNA/RNA sequences within an entire genome
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Restriction fragment length polymorphisms (RFLP)
|
-used to tell the difference between strains of mos
-enzymes added to digest the DNA and electrophorisis is ran -bands are compared |
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Normal flora
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helps protect from colonization by pathogens
-nutrition -helps sitimulate immnune system |
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Pathogenic bacteria
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virulent organisms where common exposure results in disease
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opportunistic pathogen
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-pre-existing bacteria cause disease
-wouldn't usually cause disease |
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actue disease
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rapid onset, usually rapid resolution
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chronic disease
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slow onset, slow resolution
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recurrent
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accute bouts of disease without long lasting immunity
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pyogenic
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-lots of white blood cells produced
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immune-mediated disease
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antibody or cellular responses to organisms cause tissue damage
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Methods for entry into a host
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-ingestion
-inhalation -trauma -needles -arthopod bites -sexual transmission -eyes |
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Bacterial virulence factors
|
-adherence
-cell invasion -exotoxins -superantigens -capsules -evasion of immune defenses -iron aqcuisition -motility |
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Molecular Koch's postulates
|
a genetic approach to the discovery of virulence factors
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MO Koch 1
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the phenotype or property under investigation shoudl be associatd with pathogenic members of the genes
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MO Koch 2
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specific mutagenesis of the genes associated with the suspected virulence trait should lead to a measurable loss in virulence in appropriate model systems
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MO koch 3
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complementation of the mutation either on a plasmid or by allelic replacement or the mutated gene should lead to restoration of pathogenicity
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What are the methods of adherence
|
-pili/fimbriae to host or other bacteria
-non fimbrial surface protiens -capsule -lipoteichoic acids -flagella |
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How are bacteria able to invade host cells and avoid killing
|
by stoping the binding of the phagosome and lysosome.
-able to live within the lysosome |
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What are some other ways a bacteria can live intracellular in host
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-w/i the cytoplasm
-w/i just the endosome -w/i the phagolysosome -special parasite vesicles |
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T or F
Some intracellular bacteria are able to spread cell to cell without ever leaving a host cell again |
True
-activate actin on the surface of the host that creates a projectile into the next cell |
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Bacterial exotoxins work with an AB subunit model...explain
|
they use 2 subunits
-the first peptide will bind to the host cell and initiate intoxication -second actually has the toxic activity |
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Cytolytic toxins =
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hemolysins
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Methods bacterial use to evade hosts immune response
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-capsules
-antigenic variation -anti-immunoglobulin preteases -disrupt complement -inhibit chemotaxis -leucotoxins--> destroys phagocytes -intracellular replication |
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Bacterial exotoxins work with an AB subunit model...explain
|
they use 2 subunits
-the first peptide will bind to the host cell and initiate intoxication -second actually has the toxic activity |
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Cytolytic toxins =
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hemolysins
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Methods bacterial use to evade hosts immune response
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-capsules
-antigenic variation -anti-immunoglobulin preteases -disrupt complement -inhibit chemotaxis -leucotoxins--> destroys phagocytes -intracellular replication |
