Causes of Community-Acquired Diarrhoea
| Cause | Clinical features | Diagnosis/treatment (if indicated) |
|---|---|---|
Campylobacter enteritis (C. jejuni) | Incubation period 2–6 days. Associated fever and abdominal pain. Diarrhoea initially watery, later may contain blood and mucus. Usually self-limiting, lasting 2–5 days. May be followed after 1–3 weeks by Guillain-Barré syndrome (p. 434) | Culture of C. jejuni from stool. Azithromycin 500 mg od PO for 5 days or Erythromycin 500 mg 12-hourly PO for 5 days. |
Non-typhoid salmonellosis (Salmonella species) | Incubation period 1–2 days. Associated fever, vomiting and abdominal pain. Diarrhoea may become bloody if colon involved. Usually self-limiting. More severe in immunosuppressed. | Culture of Salmonella species from stool. Ciprofloxacin 500 mg 12-hourly PO for 5 days or trimethoprim 200 mg 12-hourly PO for 5 days. |
| Escherichia coli O157:H7 (enterohaemorrhagic E. coli) | Incubation period 1–3 days. Associated vomiting and abdominal pain. May have low-grade fever. Watery diarrhoea which may become bloody. May be complicated by haemolytic uraemic syndrome from 2–14 (mean 7) days after onset of illness. | Culture of E. coli O157 from stool (using sorbitol MacConkey agar; missed by standard culture). Supportive treatment. Antibiotic therapy unhelpful. |
| Clostridium difficile colitis | Typically causes diarrhoea in hospital, but may occur in community. See Table 22.4. | |
| Norovirus | Usually short incubation time (1–2 days). Diarrhoea with vomiting is typical, with fever less common. Infections during outbreaks are more severe, with the elderly at particular risk of excess mortality. | The diagnosis is made by PCR analysis of stool and vomitus and the exclusion of other causes. Treatment is supportive. |