Gastroenteritis Flashcards
Sources of GI infections:
1) Infected food and water
2) Fecal-oral transmission (via contaminated objects)
3) Person-to-person transmission
Most likely illness in recent travelers:
ETEC (enterotoxigenic E. coli)
Most likely illnesses in food-borne infections:
Norovirus Salmonella (NOT typhi) Toxoplasma Listeria Campylobacter
Food-borne infections (1-6 hour incubation):
Staph aureus: mayo, cream pastry, ham, poultry
Bacillus cereus: fried rice
Food-borne infections (8-14 hour incubation):
Clostridium perfringens: beef, poultry, legumes, gravy
Bacillus cereus: meat, vegetables, dried beans, cereals
Food-borne infections (>16 hour incubation):
Vibrio cholera: shellfish
Vibrio parahemolyticus: oysters, shellfish
ETEC: salad, cheese, meat, water
Salmonella: beef, poultry, eggs, dairy
Shigella: potato or egg salad, lettuce, raw vegetables
Most likely illness following antibiotic treatment:
Clostridium difficile
Most likely illness following sexual contact:
Shigella (among MSM). Hepatitis A.
Most likely illness from pets:
Salmonella from reptiles and amphibians. Recent turtle outbreaks of S. enterica.
Most likely in the immunodeficient:
Cryptosporidium, microsporidium, cyclospora, isospora.
Most likely in pregnant women:
Listeria, hepatitis E
Most likely in the young:
Rotavirus, norovirus
Causes of non-inflammatory (enterotoxic) diarrhea:
Vibrio cholerae Clostridium perfringens Bacillus cereus ETEC Rotavirus Giardia Cryptosporidium
Causes of inflammatory (invasion or cytotoxic) diarrhea:
Shigella Salmonella (not Typhi) Campylobacter EHEC EIEC Yersinia enterocolitica Vibrio parahemolyticus Clostridium difficile Entamoeba histolytica
Causes of penetrating diarrhea:
Salmonella typhi
Yersinia enterocolitica
Diarrhea:
Acute (0-14 days)
Persistent (>14 days)
Chronic (>30 days)
Although gastroenteritis is typically self-limited, the following scenarios require further work-up:
Bloody diarrhea
Profuse diarrhea with evidence of hypovolemia
Small volume stools with blood and mucus
Hospitalized, immunocompromised, and pregnant patients
Fever or other evidence of systemic disease
Duration of symptoms >48 hours, or >6 stools in 24 hours
Diarrhea in the setting of recent antibiotic exposure.
Testing in gastroenteritis:
Fecal WBC
Lactoferrin
Stool culture (salmonella, shigella, campylobacter, EHEC)
Ova and parasites (giardia, cryptosporidium, Entamoeba histolytica)
C. diff toxin antigen
Treatment:
Generally not required.
Rehydration is critical.
Some organisms (EHEC) worsen with antibiotic therapy.
Non-infectious causes of diarrhea:
Inflammatory bowel disease GI tumor Endocrine disease (carcinoid) Secretory diarrhea (laxatives) Medication associated diarrhea (NSAIDs, colchicine, metoclopramide) GI bleeding IBS Ischemic colitis Radiation colitis Necrotizing enterocolitis Bowel prep for colonoscopy
Norovirus:
Damages brush border, preventing uptake of water and nutrients. Associated with outbreaks. Presents with acute onset of vomiting, mild fever, abdominal cramps, non-bloody diarrhea. Duration 1-2 days.
Diagnosis via PCR.
Rotavirus:
Main cause of pediatric diarrhea. 2 day incubation. Vomiting and watery diarrhea for 3-8 days, can be associated with fever and abdominal pain.
Diagnosis via rapid antigen detection.
Shigella (S dysenteriae, flexneri, sonnei):
Invades colonic epithelia, causing superficial ulceration and colitis with abscesses, impaired absorption of water and electrolytes.
Fecal-oral transmission. Predilection for children, daycare, poor sanitation, and MSM.
Causes dysentery with fever and blood flecks in stool. Children can develop HUS due to Shiga toxin.
Diagnosis via stool culture.
Treatment: AMPICILLIN (TMP/SMX or CIPRO for resistant strains). Avoid anti-motility agents.
Salmonella typhi (typhoid fever):
Organisms penetrate mucosa, are carried to lymph nodes and blood with secondary excretion into intestine from bile. Humans may serve as reservoirs. NO ANIMAL RESERVOIR. Presents with malaise, myalgias, headache, and high fever. ROSE SPOTS and TEMPERATURE-PULSE DISSOCIATION are common. Intestinal perforation is possible. Blood culture positive early, stool culture positive later.
Treatment: ampicillin, TMP/SMX, ciprofloxacin
Prevention: live oral vaccine
