E. coli!! MICROM 442 Deck 20 Flashcards
E.coli is GM + or -?
GM-
does ecoli ferment lactose?
yes
is ecoli indole positive or negative
positive
what type of anaerobe is ecoli?
facultative
what type of pathogen is ecoli?
enteric
ecoli is the predominant GM- facultatively anaerobic bacteria in?
human GI tract
which settings is ecoli found where it is mmutualistic and lacks virulence?
soil, vegetables, water, undercooked meat
IPEC = intestinal pathogenic ecoli. symptoms =
diarrhea with onset more than 16 hrs after ingestion
ExPEC: extraintestinal pathogenic E. coli, symptoms =
UTI, bacteremia, pneumonia, peritonitis, meningitis
nosocomial infection: hospitals and long-term care
-catheter associated UTI [CAUTI]
- ventilator associated pneumonia [VAP] due to gastric aspiration
community acquired pneumonia [CAP] much less common
pathogenic ecoli has two branches which are?
ExPEC and IPEC
ExPEC varieties
UPEC
NMEC, SEPEC, APEC, MPEC
IPEC varieties
EPEC,
EHEC, ETEC
EAEC, DAEC, EIEC
IPEC: Acquisition of virulence determinants enables pathogenesis
- adhesion
- invasion
- reduction of infectious dose
- toxin production
ExPEC virulence onset
Translocation outside GI tract; capsule production
UPEC uropathogenic E. coli
Most common extraintestinal site of infection; second most common cause of hospitalization
behind pneumonia; most common underlying infection leading to bacteremia
UPEC virulence attributes
- adherence by Type 1 and P pili
- frequently encapsulated
- capable of invading superficial epithelial cells
- production of alpha-toxin
- CNF [cytotoxic necrotizing factor] disrupts intracellular signaling and cytoskeleton
UPEC Predisposition to occurrence?
- proximity of urethra to GI tract;
- length of urethra;
- minor trauma;
- instrumentation [catheter];
- outflow obstruction
40% women will experience UTI; UPEC)
- usually when sexually active
- GI microbiota colonizing periurethral area
- bladder of most women contain GI microbiota
after intercourse; - most instances purged by urination
ETEC enterotoxogenic E. coli = colonizing fimbria
ST and LT
ST=
heat-stable peptide toxin; stimulates guanylate cyclase leading to increased
cAMP leading to Cl and water secretion and inhibition of NaCl uptake
LT=
heat-labile toxin; classic AB subunit toxin; increases cAMP in gastrointestinal
epithelium leading to Cl and water secretion and inhibition of NaCl uptake [LT less
potent but similar to CT]
ETEC = the single most important cause of?
travelers diarrhea; infectious dose about 10e8;
contaminated food and water
EHEC/STEC enterohemorrhagic/Shiga toxin producing E. coli =
intimin facilitates adhesion/colonization