Nejm 2000;342:1716; 1993;328:1821

Cause:(Jama 1999;281:811) E. colienterotoxigenic type (50+%), rarely invasive type (E. coli Invasive Diarrhea); Salmonella sp.,campylobacter, rotavirus, et al.

Pathophys:E. colitoxin is produced while the organisms are attached to gut wall much like C. perfringens;heat-labile toxin type is delayed in onset. In the unusual invasive types, colonic wall invasion causes bloody mucus, like shigella

In salads, sewer-contaminated water (Crater Lake epidemics—Ann IM 1977;86:714). Most of acute childhood diarrhea in Brazil (Nejm 1975;293:567)

Sx:

Toxin-producing types: clear, watery diarrhea may become bloody later; fever (50%)

Invasive types: bloody mucus, fever in most, pain

Si:

Toxin-producing types: sometimes low-grade fever

Invasive types: fever

r/o other gi infections (Diarrhea)

Lab:Bact:Stool smear shows polys in invasive types, none in noninvasive types; if polys present, culture for pathogens on sorbitol-MacConkey agar, O157 antiserum test of cultured E. coli(Nejm 1995;333:364)

Rx:

(Med Let 1994;36:41)

Prevent in travelers w:

• Avoidance of high-risk foods, eg, ice, salads, milk, street foods, hot sauces (Ann IM 2002;136:884); of questionable benefit (Jama 1999;281:811)
• Antibiotic prophylaxis if willing to risk rx cmplc
• Ciprofloxacin, 1st choice, 500 mg po × 1 dose (Lancet 1994;334:1537) or qd; or ofloxacin (Floxin) 300 mg po qd; or norfloxacin 400 mg po qd
• Doxycycline 100 mg qd × 5 wk but resistance common in 1993; gi excretion means can use in face of renal or hepatic disease
• Bismuth subsalicylate (Pepto-Bismol) 60 cc or ii tabs qid (75% effective), has 2 ASA equivalents/60 cc; salicylate inhibits prostaglandins, antibiotic effect of bismuth
• Rifaximin 200 mg po qd-bid (Ann IM 2005;142:805); not absorbed, prevents 75%
• Tm/S SS po qd in children, risks allergic reaction

of diarrheal sx when traveling, may be the better approach, with:

• Loperamide HCl (Imodium) 4 mg po then 2 mg after each stool up to 16 mg po qd; used with any antibiotic below doesn't hurt, may help (Ann IM 1993;118:377; 1991;114:731); diphenoxylate + atropine (Lomotil) may worsen some types, eg, shigella (Jama 1973;226:1575); and
• Ciprofloxacin, 1st choice, 500 mg po bid × 3 d (Ann IM 1991;114:731); also gets campylobacter, salmonella, and shigella as well as the pathogenic E. coli;or norfloxacin 400 mg po bid × 3 d; or levofloxacin 500 mg po qd × 3 d, or ofloxacin (Floxin) 300 mg po bid × 3 d; all about $33/crs; or
• Azithromycin 1000 mg po × 1, or 500 mg po qd × 3 d; $32/crs generic
• Tm/S (Septra) DS bid × 3-5 d (Ann IM 1987;106:216; Nejm 1982;307:84); resistance more common than with cipro
• Rifaximin (Xifaxan) (Med Let 2004;46:74) 200 mg po tid × 3 d; nonabsorbed refampin-like antibiotic as good as cipro for non-bloody diarrhea w/o fever, but not adequate if fever or blood; $33/crs