Microbiology: Enteric bugs - bacteria 5 Flashcards
What is the presentation of EHEC?
Within 24 hours of eating contaminated food
Sudden onset of watery diarrhea –> bloody diarrhea. Can last up to 8 days
How is EHEC contracted and who gets it?
Contracted from ground beef, bad milk, contaminated water
Think childcare centers
What is the pathogenesis of EHEC?
EHEC binds to cell –> injects shigella-like toxin via type III secretion system –> Toxin cleaves 28s Ribosomal RNA –> Cell death
How is EHEC diagnosed?
Culture: Gram- bacilli,
McConkey agar: White colonies
The only sorbital negative E. coli
RADT
What is the Treatment for EHEC?
NO antibiotics ( may cause HUS) Fluid replacement + blood transfusion + Temporary dialysis
What are the microbiological characteristics of EHEC?
O157:H7
Shiga toxin (Stx) cleaves 28s RNA of ribosome
Type III secretion system
What should be included in the DDx for EHEC?
Shigella Salmonella Campylobacter EIEC C. diff
What is the presentation of ETEC?
Non-inflammatory high volume diarrhea
What is the differential diagnosis for ETEC?
ETEC
V. cholerae
V. parahemolyticus
What is the epidemiology of ETEC?
Leading cause of 3rd world diarrhea (travelers diarrhea)
Waterborne, foodborne, infants
What is the pathogenesis of ETEC?
Contaminated food/water –> Colonizes SI via fimbrae –> Secretes LT + ST –> Secretory diarrhea
What is the treatment for ETEC?
Oral rehydration therapy
What is the microbiology of ETEC?
Lac-, non-motile
LT = increased cAMP –> increased CFTR
ST = Increased cGMP –> increased CFTR
Fimbrae and pedestal formation.
What is the presentation of EIEC?
Watery diarrhea –> scant bloody diarrhea (within +/- 1 day)
Cramps, tenesmus, fever
What is the DDx of EIEC?
EHEC shigella salmonella campylobacter C. diff
What is the epidemiology of EIEC?
Travelers diarrhea (2nd to ETEC) Human's are only reservoir
What is the pathogenesis of EIEC?
3rd world person-person contact –> penetrates enterocytes –> multiply within enterocytes –> Actin tail, propulsion, shigella toxin –> cell death
How is EIEC diagnosed?
Culture: Gram- bacilli, Lac-, No decarboxylation of lysine. Non-motile
Sorbital+
What is the presentation of EPEC?
Profuse watery diarrhea +/- bloody diarrhea, +/- inflammation, no fever.
What is the DDx for EPEC?
Any infectious or inflammatory diarrhea.
What is the epidemiology of EPEC?
Leading cause of infantile diarrea
contracted from contaminated water/meat
What is the pathogenesis of EPEC?
Consumption of contaminated water/food –> moderately invasive –> Induces inflammatory response –> Intracellular replication –> decreased normal signaling transduction –> Loss of microvilli –> Osmotic diarrhea
How is EPED diagnosed?
Culture: Gram- bacilli, Lac-
What is the treatment for EPEC?
Oral rehydration therapy
What are the microbiological characteristics of EPEC?
Adherence factor = localized binding
Intimin adherence
LEE and pedestal formation.
