Chapter 122. Acute Infectious Diarrheal Diseases and Bacterial Food Poisoning (Part 9) a Loperamide should not be used by patients with fever or dysentery; its use may prolong diarrhea in patients with infection due to Shigella or other invasive organisms. b The recommended antibacterial drugs are as follows: Travel to high-risk country other than Thailand: Adults: (1) A fluoroquinolone such as ciprofloxacin, 750 mg as a single dose or 500 mg bid for 3 days; levofloxacin, 500 mg as a single dose or 500 mg qd for 3 days; or norfloxacin, 800 mg as a single dose or 400 mg bid for 3 days. (2) Azithromycin, 1000 mg as a single dose or 500 mg qd for 3 days. (3) Rifaximin, 200 mg tid or 400 mg bid for 3 days (not recommended for use in dysentery). Children: Azithromycin, 10 mg/kg on day 1, 5 mg/kg on days 2 and 3 if diarrhea persists. Alternative agent: furazolidone, 7.5 mg/kg per day in four divided doses for 5 days. Travel to Thailand (with risk of fluoroquinolone- resistant Campylobacter): Adults: Azithromycin (at above dose for adults). Alternative agent: a fluoroquinolone (at above doses for adults). Children: Same as for children traveling to other areas (see above). All patients should take oral fluids (Pedialyte, Lytren, or flavored mineral water) plus saltine crackers. If diarrhea becomes moderate or severe, if fever persists, or if bloody stools or dehydration develops, the patient should seek medical attention. Source: After Dupont. The mainstay of treatment is adequate rehydration. The treatment of cholera and other dehydrating diarrheal diseases was revolutionized by the promotion of oral rehydration solutions, the efficacy of which depends on the fact that glucose- facilitated absorption of sodium and water in the small intestine remains intact in the presence of cholera toxin. The use of oral rehydration solutions has reduced mortality due to cholera from >50% (in untreated cases) to <1%. The World Health Organization recommends a solution containing 3.5 g sodium chloride, 2.5 g sodium bicarbonate, 1.5 g potassium chloride, and 20 g glucose (or 40 g sucrose) per liter of water. Oral rehydration solutions containing rice or cereal as the carbohydrate source may be even more effective than glucose-based solutions, and the addition of L-histidine may reduce the frequency and volume of stool output. Patients who are severely dehydrated or in whom vomiting precludes the use of oral therapy should receive IV solutions such as Ringer's lactate. Although most secretory forms of traveler's diarrhea—usually due to enterotoxigenic and enteroaggregative E. coli—can be treated effectively with rehydration, bismuth subsalicylate, or antiperistaltic agents, antimicrobial agents can shorten the duration of illness from 3–4 days to 24–36 h. Changes in diet have not been shown to have an impact on the duration of illness, while the efficacy of probiotics continues to be debated. Antibiotic treatment for children who present with bloody diarrhea raises special concerns. Laboratory studies of enterohemorrhagic E. coli strains have demonstrated that a number of antibiotics induce replication of Shiga toxin– producing lambdoid bacteriophages, significantly increasing toxin production by these strains. Clinical studies have supported these laboratory results, and antibiotics are not recommended for the treatment of enterohemorrhagic E. coli infections in children. Prophylaxis Improvements in hygiene to limit fecal-oral spread of enteric pathogens will be necessary if the prevalence of diarrheal diseases is to be significantly reduced in developing countries. Travelers can reduce their risk of diarrhea by eating only hot, freshly cooked food; by avoiding raw vegetables, salads, and unpeeled fruit; and by drinking only boiled or treated water and avoiding ice. Historically, few travelers to tourist destinations adhere to these dietary restrictions. However, an intensive hygienic effort in Jamaica involving government, hotel, and tourism agencies led to a decrease in the incidence of traveler's diarrhea by 72% from 1996 to 2002. Bismuth subsalicylate is an inexpensive agent for the prophylaxis of traveler's diarrhea; it is taken at a dosage of 2 tablets (525 mg) four times a day. Treatment appears to be effective and safe for up to 3 weeks. Prophylactic antimicrobial agents, although effective, are not generally recommended for the prevention of traveler's diarrhea, except when travelers are immunosuppressed or have other underlying illnesses that place them at high risk for morbidity from gastrointestinal infection. The risk of side effects and the possibility of developing an infection with a drug-resistant organism or with more harmful, invasive bacteria make it more reasonable to institute an empirical short course of treatment if symptoms develop. The recent availability of effective nonabsorbed antibiotics such as rifaximin may lead to new prophylactic options. The possibility of exerting a major impact on the worldwide morbidity and mortality associated with diarrheal diseases has led to intense efforts to develop effective vaccines against the common bacterial and viral enteric pathogens. Recent research has yielded promising advances in the development of vaccines against rotavirus, Shigella, V. cholerae, S. typhi, and enterotoxigenic E. coli. . Further Readings Al-Abri SS et al: Travelle r's diarrhoea. Lancet Infect Dis 5:349, 2005 [PMID: 15919621] Bartlett JG: Clinical practice. Antibiotic- associated diarrhea. N Engl J Med 346:334, 2002 [PMID: 11821511] Dupont HL: Travelers' diarrhea, in Infections of the Gastrointestinal Tract , 2d ed , MJ Blaser et al (eds). Philadelphia, Lippincott Williams & Wilkins, 2002, Chap 19 Guerrant RL, Steiner TS: Principles and syndromes of enteric infection, in Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases , 5th ed, GL Mande ll et al (eds). Philadelphia, Churchill Livingstone, 2000, Chap 81 Koo HL, DuPont HL: Current and future developments in travelers' diarrhea therapy. Expert Rev Anti Infect Ther 4:417, 2006 [PMID: 16771619] Musher DM, Musher BL: Contagious acute gastro intestinal infections. N Engl J Med 351:2417, 2004 [PMID: 15575058] Okhuysen PC: Current concepts in travelers' diarrhea: Epidemiology, antimicrobial resistance and treatment. Curr Opin Infect Dis 18:522, 2005 [PMID: 16258326] Sazawal S et al: Efficacy of probiotics in prevention of acute diarrhoea: A meta-analysis of masked, randomised, placebo- controlled trials. Lancet Infect Dis 6:374, 2006 [PMID: 16728323] Tauxe RV et al: Foodborne disease, in Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases , 5th ed, GL Mandell et al (eds). Philadelphia, Churchill Livingstone, 2000, Chap 87 Bibliography Guerrant RL, Bobak DA: Bacterial and protozoal gastroenteritis. N Engl J Med 325:327, 1991 [PMID: 2057037] . Chapter 122. Acute Infectious Diarrheal Diseases and Bacterial Food Poisoning (Part 9) a Loperamide should not be used by patients with. RL, Steiner TS: Principles and syndromes of enteric infection, in Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases , 5th ed, GL Mande ll et al (eds). Philadelphia,. 2006 [PMID: 16728323] Tauxe RV et al: Foodborne disease, in Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases , 5th ed, GL Mandell et al (eds). Philadelphia,