Enteroaggregative E. coli Infection

Enteroaggregative Escherichia coli (EAEC) adheres to the intestinal mucosa in a stacked brick pattern, forming a biofilm and releasing enterotoxins and cytotoxins.

• It causes acute and persistent diarrhoea in children, travellers and people with HIV.
• It is among the most common bacterial causes of diarrhoea in Africa and a contributor to environmental enteric dysfunction and growth faltering.
• A German outbreak strain carrying Shiga toxin caused severe haemolytic uraemic syndrome.

Watery, mucoid diarrhoea, sometimes with low grade fever and occasional blood; incubation 8 to 52 hours.

• Persistent diarrhoea (over 14 days) is characteristic; HIV-infected adults develop chronic diarrhoea.
• Differential diagnosis: other diarrhoeagenic E coli, Cryptosporidium, Giardia, Cyclospora, cytomegalovirus colitis, inflammatory bowel disease, coeliac disease, HIV enteropathy.
• Complications: dehydration, malnutrition, growth stunting, cognitive deficits, chronic diarrhoea in HIV, and haemolytic uraemic syndrome with Shiga toxin carrying strains.

Stool PCR for aggR or aatA genes; culture with HEp-2 adherence assays is research based.

• Full blood count, electrolytes and creatinine in severe illness.
• Stool microscopy, modified acid fast stain and antigen tests for protozoa; CD4 count and viral load in HIV.
• Faecal calprotectin when inflammatory bowel disease is possible.

Supportive: oral rehydration (50 to 100 mL/kg over 4 hours), intravenous fluids for severe dehydration, nutritional rehabilitation and zinc 20 mg daily for 10 to 14 days (10 mg under 6 months).

Pharmacological

• Antibiotics for persistent diarrhoea, HIV, or moderate to severe disease: ciprofloxacin 500 mg twice daily for 3 days (children 15 mg/kg twice daily for 3 days), azithromycin 500 mg once daily for 3 days (children 10 mg/kg once daily for 3 days), or rifaximin 200 mg three times daily for 3 days (age 12 years and over).
• HIV with chronic diarrhoea: optimise antiretroviral therapy, and add nitazoxanide 500 mg twice daily for 3 days if cryptosporidiosis is a co-pathogen.
• Avoid antibiotics if a Shiga toxin gene is detected.

Special groups: children with persistent diarrhoea (therapeutic feeds, micronutrients including vitamin A and zinc), pregnancy (azithromycin), travellers (rifaximin 200 mg three times daily for 3 days).

Red flags: bloody diarrhoea with thrombocytopenia and rising creatinine (haemolytic uraemic syndrome), weight loss, severe malnutrition.

Follow-up: weight and growth monitoring; stool recheck is not needed after recovery; water, sanitation and hygiene improvements.