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214 Cards in this Set

  • Front
  • Back
Replication enzyme prokaryotes?
DNA Pol III
Replication error rate prokary
1 in 10 million
Transcription enzyme prokary
RNA Pol
No primer required
Bacterial Ribosome
50S + 30S = 70S
Eukaryotic Ribsome
60S + 40S = 80S
Function of aminoacyl-tRNA synthetase
add amino acid to anticodon
Function of peptidyl transferase
forms peptide links between adjacent amino acids using tRNAs during the translation process of protein biosynthesis
Transformation
-uptake of naked DNA by recipient cell

-active process requiring specialized machinery

-usually transfers small amt of DNA
Transduction
-mediated by bacteriophage

1-2% of chromosome (30-60 genes) ... a large amount
Generalized transduction
any fragment of bacterial chromosome transferred
specialized transduction
one genes next to insertion site transferred (lysogeny)
Lytic transduction
life cycle of bacteriophage that ends in lysis of bacterial host cell and release of viral progeny
lysogeny
alternate life cycle of some bacteriophages where the viral genome is integrated into the bacterial chromosome
prophage
bacteriophage integrated into bacterial chromosome
Lysogenic conversion/phage conversion
toxin genes added to prophage
Conjugation
plasmid mediated

can transfer large amounts of genetic information

physical contact between cells (Pilus) must be F+ for pilus formation
Plasmids
extra-chromosomal genetic material

replicon- can be replicated independent of chromosome

encode toxins, Ab resistance, heavy metals
Transposons
"jumping genes"

conservative or duplicative

can cause insertional mutation
IS element
insertional sequence

inverted terminal repeats

encodes transposase
Composite transposon
IS elements flanking internal sequence (e.g. drug resistance gene)
Mutation frequency
10^-7
Types of mutations
base substitution
-AA change
-nonsense
-silent

frameshift mutation
-deletion
-insertion
UV light causes
thymine-thymine dimers
Transition
Replace purine w/ purine or pyrimidine w/ pyrimidine
Transversion
Replace purine w/ pyrimidine or vice versa
Restriction endonucleases
originally a defense against bacteriophage

cuts DNA from any source

cuts at specific restriction sites
Cloning
cut and paste

amplify gene of interest

vector
-unique restriction site
origin of replication
selectable marker
often plasmid or viral
Southern Blot
Fractionation of DNA fragments on gel by size (electrophoresis)

Transfer to membrane

Hybridization

Use probe to find DNA of complementary sequence
Types of Blots
Southern- DNA, probe is oliqonucleotide, used to see if gene is present/ identify organism

Northern- mRNA, probe is oligonucleotide, looks to see if gene is expressed

Western Blot- SDS gel, proein, probe is Ab, looks to see if protein produced
Array hybridization
Looks at expression of hundreds of genes at once

Oligos to each gene arranged on blot

Probe with cDNA (mRNA)
Peptidoglycan
Cell wall material (murein)

Crosslinked NAG-NAM-NAG formed by transpeptidases
Gram + cell wall characteristics
Thick peptidoglycan wall w/ teichoic and lipoteichoic acid

Single inner cell membrane
Gram - cell wall characteristics
Thin cell wall between outer and inner membranes.

LPS on outermembrane

Lipoprotein connects outer membrane to cell wall
Lipoteichoic acid
anchors cell wall to membrane in gram +'s
Lipoprotein
Anchors cell wall to outer membrane in gram -'s
Periplasm
space between membranes in gram - bacteria. organization and degradation of cell wall occurs here
Functional barrier of gram - bacteria
inner cell membrane
Siv like barrier of gram - bacteria
outer membrane
Lipopolysaccharide
Only found in gram -

Consists of Lipid A, Core poly, and O-antigen repeating subunits

Lipid A forms toxic portion of endotoxins
Gram stain procedure
1. Fix cells to slide
2. Add crystal violet
3. Add iodine solution
4. Wash w/ mild solvent
5. Counter-stain with safranin
Site of action of penicillins and cephalosporins, also can be degraded by lysozyme
Cell wall peptidoglycan
Site of action of aminoglycosides, erythromycin, tetracyclines, and chloramphenicol
Bacterial ribosome
Chemical composition of endospore
Keratinlike coat with dipicolinic acid, provides resistance to dehydration, heat, and chemicals
Bacterial repoduction
Binary fission
-DNA replication
-Chromosome segregation
-Septum formation
-Cytokinesis
Bacterial growth phases
Lag phase
Exponential growth phase (log)
Stationary phase
Decline and death
Glycolysis
Sugar converted to pyruvate yielding 2 ATP per glucose
Superoxide dismutase
converts oxygen free radicals to peroxide (h202)
Catalase or Peroxidase
Decomposes peroxide to H20
Aerobe
Need 02 for terminal electron receptor
Facultatives
Can use 02, but can also use fermentation or other e- acceptors
Aerotolerant
Dont use 02, but are OK with it
Strict anaerobes (obligate)
Lack SOD and catalase
Ferment or use another e- acceptor
Microaerophiles
Thrive is low 02 (5%)
Pathogen
any organism capable of producing dz

normal flora becoming pathogenic are termed opportunistic
ID50/LD50
number of organisms required to infect or kill 50% of exposed individuals
incidence
number of cases
prevalence
percentage of population at a given time
endemic
always present
epidemic
outbreak through a population
pandemic
epidemic of global proportions
Incubation
time between exposure and symptoms
Prodromal period
onset of non-specific symptoms
Acute period
characteristic symptoms of dz
Pathogen characteristics
Transmission
Adherence
Invasiveness
Toxigenesis
Methods of invasion
Penetration (collagenases/hyaluronidases)

Coagulation

IgA protease

Leukocidins- knock off phagocytic cells
Endotoxin found in
Gram - bacteria only
Exotoxin found in
Gram - and +
Sampling
aspirated pus, swab, paperpoint

microscopic eval

culture
Antibiotic screening
Bacteria spread in lawn on plates

Seeded with Ab discs

Zones of inhibition reflect sensitivity to Ab

Can be done in liquid culture as well
Traveler's diarrhea cause
Enterotoxigenic E. coli (ETEC)

Emerged in 60s
ETEC Toxins
Heat-stable (ST) - ^cGMP, increased fluid secretion

Heat-labile (LT) - ^cAMP, electrolyte shift
ETEC clinical findings
diarrhea, cramps, fever, nausea
ETEC incubation/resolution
1-3 days, 3-4 days

Dx by culture
ETEC Tx
Tx symptoms

No Rx needed
E. coli 0157:H7 toxin
Lysogenic phage encodes Verotoxin
E. coli 0157:H7 Epidemiology
73,000 cases and 60 deaths a year in US
E. coli 0157:H7 Transmission
Oral/fecal contamination
E. coli 0157:H7 clinical findings
Bloody diarrhea/cramps/no fever

Resolves in 5-10 days

Hemolytic uremic syndrome (HUS) in young/old
E. coli 0157:H7 Dx
Growing on sorbitol-MacConkey agar
E. coli 0157:H7 Tx
Treat symptoms, No Rx
E. coli O104:H4 toxin
Shiga toxin
Salmonella enteritidis clinical findings
Gastroenteritis, diarrhea, fever, cramps, bacteremia can develop
Salmonella enteritidis transmission
oral-fecal, person to person, contaminated food (beef/poultry)
Salmonella enteritidis morphology
gram - rod
Escerichia coli morphology
gram - rod
Salmonella typhi morphology
gram - rod
Salmonella typhi/paratyphi causes
enteric fever (typhoid fever)
Salmonella typhi/paratyphi clinical findings
headache, malaise, anorexia, diarrhea/constipation, inflammation of liver/spleen lasting for 3-4 weeks

(12-30% mortality w/o tx)
Salmonella typhi/paratyphi clinical exam findings
rose-colored spots on chest
Salmonella typhi/paratyphi tx
Ab tx but resistance is high
Salmonella typhi/paratyphi transmission
contact, food, sewage, lives only in people

chronic carriers
Salmonella Newport
emerging, Ab resistant strain of S. typhi
Most common Shigella
S. sonnei 72% of cases
S. flexneri most of rest
Shigella toxin
Shiga
Shigella clinical findings
diarrhea, fever, cramps

1-2 day incubation

may cause seizures in kids

resolves 5-7 days

2% of S. flexneri develop Reiter's syndrome
Reiter's syndrome
develops in 2% of S. flexneri cases

joint pain, eye irritation, painful urination
Shigella tx
Antibiotics
Shigella transmission
oral-fecal, p2p
Shigella morphology
non motile, gram - rod
Pathogen in "Hot tub rash"
Pseudomonas aeruginosa
Pseudomonas aeruginosa morphology
Gram - rod
Pseudomonas aeruginosa clinical findings
Dermatitis/folliculitis

Itchy/red bumpy rash

Pus-filled blisters at hair follicles

Can cause pneumonias in immunocompromised and infections in burns
Pseudomonas aeruginosa transmission
heavily contaminated water contact
Haemophilus influenzae morphology
Gram - rod, opportunist (Upper resp tract infection)
Haemophilus influenzae pathology
HiB
-Bacteremia
-Epiglotittis
-Meningitis (5% mortality, 10-30% brain damage)

-HiB vaccine
Neisseria morphology
Aerobic gram - diplococci
Neisseria gonorrhea transmission
contact
Neisseria gonorrhea clinical findings
burning sensation, discharge

sore throat in oral infection

infects reproductive tract, mouth, throat, and eyes
Neisseria gonorrhea effects if untreated
PID/infertility in women

Infertility in men

Risk of bacteremia
Neisseria gonorrhea Tx
Antibiotics
Neisseria meningitidis pathology
Meningococcus
Meningococcemia

10-15% fatality rate
Neisseria meningitidis symptoms
fever, headache, stiff neck
nausea, vomiting
seizures
Neisseria meningitidis resides in
nasopharynx
Neisseria meningitidis dx
Spinal tap
Neisseria meningitidis tx
IV antibiotics, MUST tx rapidly!
Rickettsiaceae morphology
Gram -, pleiomorphic, non-sporulating rods
Rickettsiaceae transmission
Ticks, fleas, lice

Obligate intracellular parasites
Rickettsiaceae pathology
RMSF

Typhus
Rickettsia richettsii pathology and transmission
Rocky Mountain Spotted Fever transmitted by ixodid (hard) ticks, Dermacentor
Rickettsia richettsii symptoms
Rapid
Fever, headache, muscle pain
Rash, abdominal/joint pain

Fatal if untreated
Rickettsia richettsii Treatment
Antibiotics (Doxycycline or Chloramphenicol)
Rickettsia prowazekii causes
Epidemic Typhus
Rickettsia prowazekii transmission
Human body louse

May be flying squirrel vector
Rickettsia prowazekii symptoms
Headache, chills, fever, prostration, confusion, photophobia, vomiting, rash
Rickettsia prowazekii Tx
Antibiotics
Vibrio cholera morphology
slender, gram - rod
Vibrio cholera causes
Cholera
Vibrio cholera fatality rate if untreated
25-50%
Vibrio cholera transmission
oral/fecal

lives only in humans
Vibrio cholera symptoms
"rice water" stool

electrolyte gradient disrupted by cholera toxin

circular collapse and shock occur eventually
Vibrio cholera Tx
Rehydrating electrolytes, reduces fatality to 1%
Campylobacter morphology
Curved, gram - rods
microaerophilic/thermophilic
Campylobacter jejuni reservoirs
livestock/pets
Most common cause of bacterial diarrhea
Campylobacter jejuni
Campylobacter jejuni symptoms
Fever, cramps, diarrhea
Resolves in a week

0.1% of cases develop Guillain-Barre syndrome

Becoming resistant to Antibiotics
Chlamydia trachomatis symptoms
Ocular infections
-neonatal conjunctivitis
-blindness

General infections
-"silent epidemic"
PID
Damage may be irreversible
Pneumonia in neonates
Chlamydia pneumoniae symptoms
Acute respiratory infection
Chlamydia Dx
Fab test
Chlamydia Tx
Tetracycline
Treponema morphology
Spirochaetes
Treponema in oral cavity
Strict anaerobes, role in perio
T. denticola, vincentii, etc
Causitive agent of Sphyilis
Treponema pallidum
Treponema pallidum symptoms
Syphilis
Primary
-smooth, round chancre
resolves after 3-6 weeks

Secondary
-rash and lesions, fever, swollen lymph, sore throat, patchy hair loss, headaches, weight loss, muscle aches, fatigue

Late stage
-brain, nerves, eyes, heart, blood vessels, liver, bones, and joints
Treponema pallidum tx
antibiotics (IM penicillin G)
Borrelia burgdorferi causes
Lyme dz
Borrelia burgdorferi transmission
black legged ticks
Borrelia burgdorferi symptoms
Lyme dz
70-80% develop erythema migrans 3-30 days post bite

"Bell's" palsy, meningitis, heart arrythmia, arthritic symptoms
Borrelia burgdorferi dx
Serology
Borrelia burgdorferi Tx
antibiotics
Borrelia burgdorferi morphology
spirochete
Borrelia burgdorferi morphology
spirochete
Mycoplasma morphology
tiny, pleomorphic, no cell wall
Mycoplasma pneumoniae symptoms
Atypical pneumonia

can cause oral erythematous patches
Mycoplasma pneumoniae transmission
p2p
Mycoplasma pneumoniae dx and tx
difficult to dx, antibiotics
Helicobacter morphology
Gram -, spiral, microaerophile
H. pylori symptoms
peptic ulcers

most common chronic infection
H. pylori dx
serology, endoscopy
H. pylori tx
antibiotic
Legionella pneumophilia morphology
thin, pleomorphic gram -
Legionella pneumophilia transmission and diseases
Respiratory

Causes Legionnaires' dz and Pontiac fever

Often contracted after overnight stay out of home, often associated with water reservoir
Pontiac Fever symptoms
short incubation followed by flu-like illness without pneumonia in a majority of people
Legionnaires' dz symptoms
Longer incubation followed by enigmatic pneumonia in <5% of those exposed

High fatality rate (5-40%)
Legionella pneumophilia dx
Serology
Clostridia morphology
Gram +, anaerobic, sporulating rods

Normally found in soil, noted for production of toxins
Clostridium perfringens transmission
ubiquitous in the environment
Clostridium perfringens causes
necrotizing infections and gas gangrene

fever, pain, myonecrosis, gas
Clostridium perfringens toxin
Alpha toxin

catalytically disrupts membranes leading to edema
Clostridium perfringens symptoms
fever, pain, myonecrosis, gas

tissue damage can lead to amputation

progression to bacteremia can prove fatal
Clostridium perfringens dx
Culture, microscopy, tissue imagaing
Clostridium perfringens tx
surgery, antibiotics, hyperbaric 02
Clostridium botulinum found
in soil
Clostridium botulinum toxins
Seven types

Alpha type most deadly biological toxin known

Blocks ACh release leading to flaccid paralysis
Clostridium botulinum pathologies
Three that vary w/ transmission

Food borne- toxin produced by growth in improperly preserved food. Non-acidic foods (beans, corn, hot peppers)

Wound botulism- bacteria introduced into wound, increased incidence w/ heroine use

Infant botulism- infant ingests contaminated food. Bacteria reproduces in gut, produces toxin. From honey, corn syrup, etc
Clostridium botulinum dx
By symptoms and patient hx
Clostridium botulinum tx
antitoxin (human for infant, equine for others)

respiratory assistance
Clostridium tetani symptoms
causes tetanus "lock jaw"
Clostridium tetani transmission
introduced into deep wounds (anaerobic)
Clostridium tetani toxins
produces tetanolysin and tetanospasmin

Tetanospasmin blocks GABA
-cause intense muscle spasm
Clostridium dx and tx
Dx- symptoms
Tx- antitoxin and antibiotics
Clostridium difficile transmission
Found in soil, occasionlly part of normal gut flora for some
Clostridium difficile toxins
A toxin- exotoxin that acts enterically

B toxin- cytotoxin
Clostridium difficile symptoms
Causes pseudomembraneous colitis (PMC), toxic megacolon, perforations of the colon, sepsis

Watery diarrhea, fever, anorexia, nausea, abdominal pain and occasionally death
Clostridium difficile tx
antibiotics, GI surgery, long stay in health care facilities, immunocompromised
Clostridium difficile dx
stool culture, antigen detection, toxin detection
Streptococci morphology
gram positive, chain forming cocci

wide distribution
Streptococci dx and culture
Hemolytic characterization
-grown on blood agar plates

Three posibilities
-No hemolysis

-Alpha-hemolysis
--narrow zone of partial lysis and discoloration

- beta-hemolysis
--wide, clear zone of complete hemolysis
Streptococcus pneumoniae characteristics
alpha-hemolytic
gram +, chain forming cocci
Streptococcus pneumoniae symptoms
Pneumonia and meningitis in adults, otitis media, and sinusitis in children

Can cause:
-hearing loss
-neurological impairment
-death during invasive dz (14% of hospitalized adult)
Streptococcus pyogenes characteristics
Group A Streptococci (GAS)
Beta-hemolytic, hemolysins, hyaluronidase

gram +, chain forming cocci
Streptococcus pyogenes pathologies
non-invasive strep throat and impetigo

red sore throat, may have white/yellow patches

can cause scarlet fever (scarlatina)

Invasive necrotising faciitis, toxic shock (STSS), cellulitis,

>35% STSS, 25%NF, Death in 10-15% of invasive cases
Streptococcus agalactiae characteristics
Group B streptococci
beta-hemolytic

gram+ chain forming cocci
Streptococcus agalactiae pathologies in neonates
Sepsis, pneumonia, meningitis in neonates
Streptococcus agalactiae pathologies in adults
Sepsis and soft tz infections
Streptococcus agalactiae pathologies during pregnancy
Sepsis, amnionitis, UTI, stillbirth
Staphylococci characteristics
Gram+, cluster forming cocci
Staphylococcus epidermidis pathologies
normal flora

can cause wound, catheter infections
Staphylococcus aureus pathologies
superficial infections
food poisoning
toxic shock syndrome
deep infections
S. aureus superficial infections symptoms
boils, carbuncles, abscesses, conjunctivitis
S. aureus food poisoning
Enterotoxins
produced in food and consumed
very fast
reduced w/ proper handling
S. aureus toxic shock syndrome
replication and production of specific enterotoxin in body

wounds and burns
pharynx
tampons

Sx:
fever, malaise, stupor, organ failure
Resistance in Staphylococcus aureus
MRSA
VISA/VRSA
-resistance to penicillin related drugs

Nosocomial infections are most transmissions/infections
Listeriosis morphology
Gram+ rod
Listeria monocytogenes transmission
Gram+ rod,

food borne transmission
-meat, poultry, dairy, vegetables
-rarely reported noscomial
Listeria monocytogenes pathologies
Long incubation

Gastroenteritis
Pregnancy related and neonatal infection
-fetal sepsis/meningitis leading to stillbirth

Sepsis and meningitis in adults
Bacillus anthracis characteristics
Gram+ sporulating rod
Bacillus anthracis toxins
Edema factor- alters cAMP levels in MOs

Lethal factor- triggers apoptosis

Protective factor- shuttle EF and LF to cell
Bacillus anthracis transmission and symptoms
Associated w/ large herbivores, most human infections are related to animal contact

Cutaneous
-cuts/abrasions
raised, itchy bump that ulcerates
edema and swelling
fatal in 20% of cases w/o tx
Anthrax pathologies
Intestinal
-ingests contaminated meat
-nausea, anorexia, vomiting, fever, pain, sever diarrhea
-fatal 25-60%

Inhalation
-inhalation of spores followed by cold-like symptoms
-progesses rapidly to respiratory collapse and shock
-Usually fatal w/o tx
Anthrax dx and tx
Culture/serology

Treated w/ heavy course antibiotics
Mycobacterium tuberculosis characteristics
slender rods, do not take up gram stain (acidfast) because of mycolic acid in cell wall
Mycobacterium tuberculosis pathologies
Primary infection
-local lesions (Ghon focus), local lymphs enlarge
-usually becomes dormant upon cell mediated response
-left untreated it can reemerge after months or years causing fatal pathology

Post-primary infections
-miliary TB
--spread to multiple foci
-meningitis, bone/joint, renal
-Tubercular bronchopneumonia
--75% emergent infection
anorexia, fatigue, fever, night sweats, cough, bloody sputum
pleural effusion and lung collapse
Mycobacterium tuberculosis dx
Mantoux test (TST)
-intradermal injection of purified protein derivative (PPD)
-hard lesions form due to immune reaction
Mycobacterium tuberculosis tx
Combination drug therapy
-multiple antibiotics over long course
Vaccine w/ live vaccine somewhat effective
-Bacillus Calmette-Guerin (BCG)