Severe infectious diarrhea

It is estimated that in some countries between a quarter and a half of childhood mortality is related to diarrheal disease. The risk to adults from associated dehydration, electrolyte imbalance, and weight loss is less, but nevertheless can be life threatening. Intercurrent infection with pneumonia or septicemia is common. Opportunistic infections in patients with AIDS are an increasing cause of severe diarrhea but rarely require intensive care.

Food poisoning

Common causes of food poisoning in developed countries are Salmonella, Shigella, Staph. aureus, and C. perfringens. Salmonella, Shigella, Yersina, and Campylobacter are invasive and cause an inflammatory diarrhea which may lead to fever and abdominal pain. The stools can contain blood or mucus but more often are watery. Preformed enterotoxins cause diarrhea ssociated with Staph. aureus. It is usually a self-limiting disease with onset within hours of eating contaminated food. The enterotoxins are not absorbed, and, although the precise action is unclear, the result is increased net water and electrolyte secretion by the gut. C. perfringens type A causes a non-invasive non-inflammatory perfuse watery diarrhea, commonly accompanied by abdominal pain, starting 8 to 24 h after ingestion of contaminated food and lasting for 12 to 24 h. The C. perfringens type A enterotoxin is heat labile and impairs electrolyte transport and water absorption in the ileum. C. perfringens type C, which is usually acquired from undercooked pork and largely confined to New Guinea, Thailand, Nepal, and China, causes enteritis necroticans.

E. coli

At least five groups of E. coli causing diarrhea have been identified (Can]ey 199.3): enterotoxigenic, enteroinvasive, enteropathogenic, enterohemorrhagic, and enteroadherent. The enteroinvasive E. coli causes a similar syndrome to Shigella. The serotype 0157:H7 and other serotypes cause bloody diarrhea. The hemolytic-uremic syndrome complicates approximately 30 per cent of enterohemorrhagic infections. Thrombotic thrombocytopenic purpura is a less frequent complication.

V. cholerae

V. cholerae, which is an important cause of severe diarrhea in developing countries, may be acquired from water, rice, or seafood. The majority of people infected do not develop diarrhea; only 2 to 5 per cent develop the 'typical' severe diarrhea and a quarter develop mild to moderate diarrhea.


Most infective diarrhea is self-limiting. Further investigations are indicated to identify the cause when diarrhea is severe, associated with systemic symptoms, or prolonged, or for public health reasons. Microscopy, culture, and serotyping identify parasites and pathogenic bacteria. Viruses can be identified by electron microscopy or immunoassay. Molecular methods using synthetic oligonucleotide probes and polymerase chain reaction amplification are now available for identifying many enteric pathogens. These have the potential to provide faster identification to guide treatment.


Prevention and correction of dehydration and electrolyte imbalance are the most important components of treatment. Oral rehydration solutions are effective and help reduce ongoing water loss into the bowel lumen (F.a.rth.j.D.9... .1988). Intravenous rehydration may be needed when dehydration is severe or if diarrhea is accompanied by vomiting. Severe diarrhea over 48 h can result in fluid loss of 4.5 to 8.5 liters and sodium depletion of 10 to 20 mmol/kg body weight. Replacement with isotonic saline and potassium supplements is usually adequate. After very severe diarrhea a metabolic acidosis can make part replacement with isotonic sodium bicarbonate more appropriate. Antidiarrheals provide symptomatic relief but should not be used when diarrhea is caused by invasive enteropathogens, i.e. when diarrhea is bloody or accompanied by fever. Cyclo-oxygenase inhibitors (indomethacin, aspirin) appear to be effective in experimental models of secretory diarrhea, but clinical information is limited. Chloride-channel-blocking agents are being investigated as treatment for secretory diarrhea.

The place of antibiotics is controversial. Antibiotic treatment may prolong carriage of Salmonella and antibiotics do not, for example, reduce the complications of enterohemorrhagic E. coli infection. Bacteremia and extraintestinal manifestations of infection are the usual indications for antibiotics, but these can be difficult to predict and so antibiotics are also given to neonates, the elderly, debilitated patients, and the immunosuppressed. Fluoroquinolones (norfloxacin, ciprofloxacin), trimethoprim-sulfamethoxazole (co-trimoxazole), tetracycline (not for children or pregnant women), and intravenous third-generation cephalosporins have been used for empirical treatment. Otherwise, treatment is guided by culture and sensitivity results.

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