Flashcards in GI pathogens Deck (23):
most common causes of food-borne illness in US
Campylobacter spp. (bacterial)
Giardia lamblia (parasitic)
most frequent etiology of travelers diarrhea
inflammatory vs non inflammatory diarrhea
Inflammatory: mucous or blood in stool, PMNS and RBCs, local tissue destruction, fever, 2-4 day incubation period
Noninflammatory: watery stool, toxin mediated or caused by virus, no fever, 1-12 hour incubatin period
Vibrio cholerae: what kind of bacteria? where? spread?unique features?
curved gram neg rod "comma shaped", salt water (sea foods and contaminated water), causes epidemics and pandemics
what type causes cholera epidemics?
serogroup O1, two biotypes (classic and El Tor). O139 is the most recent one in India
pathogenesis of cholerae infection: load required, toxins/other things?
huge bacterial load required b/c most are killed by stomach acid. Uses pili (toxin co-regulated pili) to adhere to intestine. Toxin (CTX) is A-B and is encoded by a phage which is received by the TCP. A1 part of toxin ^ cAMP, activates CFTR channel, increasing Cl secretion and decreased Na uptake causing secretory diarrhea
clinical disease of cholera
death by dehydration in 12 hours. mucus flecks in stool "rice water". Usually no fever
diagnosis and tx of cholera
culture on TCBS agar, oxidase positive. Give fluids and antibiotics (doxycyclin/ tetracyclin)
ETEC: what is it? what does it cause? toxins?
gram neg bacilli. Enterotoxigenic E coli. Heat labile (LT: ^ cAMP leads to ^ CL secretion) and heat stable (ST: ^ cGMP leads to decreased resorption of NaCl) toxin
staph aureus food poisoning: what causes sickness?
heat stable enterotoxin (ABCDE), picnic foods. Antibiotics are not useful (illness due to toxins)
Rotavirus: significance? fever?
#1 cause of fatal diarrhea in children (day-care, kindergarten, esp in winter). yes: exception to noninflammatory fever rule.
Norovirus: what does it cause? how is it spread? where?
"stomach flu". fecal oral from not washing hands. cruises and airplanes. Also an exception to noninflammatory fever rule.
unicellar parasite. trophozoite and cyst (survives in environment) forms. fecal-oral. adheres to small intestine. gassy, fatty diarrhea
unicellular parasite. fecal-oral (cysts in water). important in AIDS. acid-fast stool stain
shigella spp.: what is it? spread?
fingers, food, flies, feces, fomites. Survives gastric acid. Transcytose M cells then live in enterocytes. Does not move to bloodstream. Hemolytic uremic syndrome
campylobacter jejuni: shape, sickness, causes, complications
curved gram-neg rod "seagull". Bloody diarrhea. Ingestion of contaminated poultry (more common than salmonella). Guillain-barre syndrome
bloody diarrhea, no fever
enterohemorrhagic e coli (EHEC)
tender abdomen with mass mimicing appendicitis
c. diff.: general?
gram+ rod, spore forming, antibiotic associate diarrhea. 2 toxins: a and b. Pseudomembranous colitis (PMC): toxic megacolon, perforation and death
c diff treatment
oral metronidazole, oral vancomycin
entamaoeba histolytica: disease? diagnosis
amebiasis: dysentery, liver abcess, flask-shaped ulcer in colon rupture. trophozoites or cysts.
clostridium perfringens: toxin? mechanism?
alpha exotoxin. Phospholipase degrades phospholipid C of cell membranes. Leads to gas gangrene and hemolysis