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How are Salmonella species referred to?
Genus Serotype
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O antigen in Salmonella
associated with LPS of the outermembrane
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H antigen of Salmonella
associated with the flagella
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What are the two Salmonella phases?
- motile/specific
- non-motile/non-specific
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pathogenic strains of S. Typhi, S. Paratyphi C and S. Dublin carry what?
Vi antigen - associated with envelope and capsule (K antigen)
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Which has a human reservoir?
- S. Typhi
- S. Paratyphi A, B, and C
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Where is Salmonella endemic?
- India
- SE Asia
- South America
- Central America
- Africa
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Pathogenesis of Salmonela Tyhpi
- 1. invades mucosa/epithelium of the small and large intestines
- 2. is engulfed by macrophages
- 3. the macrophages carry it to the liver, spleen, and bone marrow
- 4. it multiplies inside the macrophage
- 5. when a critical number is reached, it is released into systemic circulation
- 6. the reticuloendothelial system tries to control the spread by taking it up
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What is the Salmonella carrier state?
- sheds for a year or longer
- asymptomatic
- stored in gallbladder and gallstones
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In which infection does the fever appear to get better and then begin to get worse over the course of the first week?
Typhoid Fever
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In which infection does the pt get "rose" spots?
Typhoid fever
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How is Typhoid fever associated with UTIs?
not actually a UTI, its just that the salmonella is excreted in the urine
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What is used to treat typhoid fever?
- DOC: ciprofloxacin
- 3rd gen cephs
- azithromycin
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resistant to choramphenicol
Salmonella
-
resistant to ampicillin
- salmonella
- shigella
- klebsiella
-
resistant to bactrim
salmonella
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4 Shigella subgroups
- A - dysenteriae
- B - fexneri (2nd most common in US)
- C - boydii
- D - sonnei (most common in US)
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Which species of bacteria are actually biogroups of E. coli
Shigella
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highest incidence in children 6mo - 5 yrs
shigella
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peak incidence in late summer
shigella
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disease limited to humans
shigella
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resistant to stomach acid
shigella
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Shigella pathogenesis
- 1. crosses mucosa via M cells
- 2. macrophage engulfs
- 3. shigella escapes macrophage
- 4. enters mucosal cells from underneath using invasins (actin polymer rearrangement in cell's cytoskeleton that causes the bacterium to be engulfed into an endocytic vesicle)
- 5. escape from vacuole into cytoplasm and multiply
- 6. Move through host cell and spread to other cells by actin-based motility
- 7. when they reach boundary of the cell, the actin filaments push the Shigella across the membrane and into the adjacent cell
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infection associated with seizures
Shigella (b/c of fever)
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infection associated with Reiter's Syndrome (reactive arthritis)
Shigella
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Shigella group that produces Shiga-like exotoxin
S. dysenteriae
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What is used to treat Shigella?
DOC: Cipro or Bactrim
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2 categories of E. coli
- urophathogenic/extraintestinal
- "entero" associated/diarrheagenic
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virulence factors of Uropathogenic/extraintestinal E. coli
- endotoxin (LPS)
- exotoxin (hemolysin)
- capsule
- flagella
- pili (P-fimbira and S-fimbira)
- sideophores (steals host's iron)
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types of hemolysin? what infection are they associated with?
- Alpha - secreted; disrupts lymphocytes
- Beta - membrane bound; inhibits PMNs
associated with uropathogenic/extraintestinal E. coli
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types of Pili and what they are associated with
- P-Fimbria - UTI
- S-Fimbria - meningitis
associated with uropathogenic/extraintestinal E. coli
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source of uropathogenic E. coli
normal flora of colon (coliform)
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types of transmission of uropathogenic E. coli
- 1. Autoinoculation (fecal contamination of urethra)
- 2. Nosocomial, Iatrogenic (urinary/IV catheter)
- 3. Vertical (at birth bc of passage through vagina; in utero via ascending infection)
- 4. horizontal (lack of hand washing)
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most common cause of UTIs
E. coli
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treatment for uropathogenic E. coli
- UTI: Bactrim
- bacteremia: carbapenems
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resistant to beta-lactams (includes ESBL producing)
- uropathogenic E. coli
- hospital acquired klebsiella
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what can cause neonatal meningitis?
uropathogenic E. coli through S-Fibriam pili
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treatment of neonatal meningitis
cefotaxime or ceftriaxone
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groups of enteroassoicated E. coli
- enteroadhesive (EAEC)
- enterohemorrhagic (EHEC)
- enteroinvasive (EIEC)
- enteropathogenic (EPEC)
- enterotoxigenic (ETEC)
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which enteroassociated E. coli are found in the small and intestines respectively?
- small (A, P, T)
- large (H, I)
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E. coli group that is pathogenetically related to Shigella
EIEC - shigella like dysentery (invasion of intestinal epithelial cells)
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pathogenesis of EIEC
invades and destroys colonic epithelium
-
causes disease in children <2, but older children and adults are resistant
EPEC
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which E. coli doesn't produce exotoxin
EPEC
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pathogenesis of EPEC
- adherence to epithelial cell membrane
- destruction of microvilli
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most common of all E. coli diarrhea
ETEC
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most common cause of traveler's diarrhea
ETEC
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two exotoxins associated with ETEC
- heat labile (antigenic; cholera-like toxin)
- heat stable (non antigenic; rapid onset of action; limited to small intestine)
-
produces highly mucoid colonies b/c of polysaccharide capsule
Klebsiella
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role in CAP in alcoholics and ppl with chronic respiratory disease
Klebsiella
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treatment for klebsiella
- non-MDR: 1st gen ceph, pen/BLI, bactrim, FQ, aminolyc
- MDR: not many options
- ESBL producing: carbapenems, some FQs
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out of enterobacter, serratia, and citrobacter which one(s) inhabit the human gut?
enterobacter and cirobacter
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intrinsically resistant to ampicillin and 1st and 2nd gen cephs
enterobacter, serratia, and citrobacter
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associated with a "swarm" over moist agar plates
proteus
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2 species of proteus
- proteus mirabilis (indole +)
- proteus vulgaris (indole -)
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the production of ____ by proteus mirabilis leads to:
- urease
- 1. hydrolyzes urea in urine to ammonium hydroxide
- 2. urine pH goes up (more basic)
- 3. Mg, Ca, and ammonium precipitate forming triple phosphate kidney stones (struvite)
- 4. leads to renal calculi, UTIs, hydronephrosis, absecess b/c of obstruction
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types of infections btween proteus species
- mirabilis: community acquired UTIs
- vulgaris: hospital acquire infections (pneumonia, wound infections, bacteremia, septicemia)
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types of resistance btwn both proteus species
- mirabilis: generally susceptible, but with increasing resistance
- vulgaris: resistance is common
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infection confers long lasting type-specific immunity in this:
vibrio cholerae
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What are the two enterotoxins that vibrio cholerae produces and what do they do?
- choleratoxin, choleragen
- 1. stimulate adenylate cyclase
- 2. inc in intracellular cAMP
- 3. Na and Cl absorption by microvilli inhibited
- 4. promotes secretion of chloride and water by crypt cells of the intestines
- 5. leads to isotonic fluid secretions from sm. intestine that go beyond the ability of the colon to absorb the excess
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two serotypes of vibrio cholera and their symptoms:
- O1 - 50% symptomatic
- O139 - 1-5% symptomatic
watery (rice-water) diarrhea (painless, voluminous, odorless) --> severe dehydration
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complications of vibrio cholerae:
- 1. metabolic acidosis
- 2. pre-renal azotemia
- 3. iatrogenic water intoxication (w/ overhydration; aspiration pneumonia)
- 4. hypoglycemia
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treatment for vibrio cholera
- ORT or IVF
- DOC: doxy (single dose)
- tetracycline, bactrim, cipro
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which vibrio is associated with wound infections
vibrio parahaemolyticus adn vulnificus
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which species produces pigments?
pseudomonas aeruginosa (blue, yellow-green, red-brown)
smells like grapes
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which has alginate as a virulence factor and which pts are especially prone to this?
- pseudomonas aeruginosa
- cystic fibrosis pts
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dysenteric/enteroinvasive pathogens
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Watery/enterotoxigenic
- EAEC
- V. cholerae
- and basically all the other ones
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Motile
- Salmonella
- Shigella (in vivo)
- E. coli
- V. cholerae
- P. aeruginosa
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Non-motile
- Klebsiella
- shigella (in vitro)
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Lactose fermenting
- E. coli
- Klebsiella
- Vibrio's
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Non-lactose fermenting
- P. aeuroginosa
- Salmonella
- Shigella
-
Oxidase positive
P. aeruginosa
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splits urea
Proteus mirabilis
-
doesn't split urea
- salmonella
- shigella
- E. coli
- V. cholerae
-
-
doesn't produce H2S
E. coli
-
positive indole
- Klebsiella oxytoca
- Proteus mirabilis
-
negative indole
- Klebsiella pneumoniae
- Proteus vulgaris
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exotoxin
- shigella dysenteriae (Shiga toxin)
- EAEC
- EHEC (Shiga-like toxin)
- ETEC (heat labile and stable)
- V. parahaemolyticus (hemolysin)
- P. aeruginosa (exotoxin A - disrups protein sy thesis)
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Both exo and endotoxin
- E. coli
- V. cholerae (endo - LPS; exo - choleratoxin, choleragen)
-
-
special media
- v. cholerae
- v. parahaemolyticus (salt)
- v. vulnificus (salt)
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requires fresh specimen
- Salmonella
- Shigella
- V. cholerae
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