Escherichia coli enterovirulent phenotypes in Zambians with AIDS-related diarrhoea

Persistent diarrhoea is a major cause of morbidity and mortality in AIDS patients, and consequently an important public health problem in sub-Saharan Africa. Although intestinal protozoa and bacteria are detected in many of these patients, a substantial proportion of disease remains unexplained even after intensive investigation. HEp-2 cell adherent Escherichia coli have been described in AIDS patients with persistent diarrhoea, but their contribution to the overall burden of disease is not yet defined. We studied HEp-2 cell adherence of E. coli isolates from 116 adult Zambian AIDS patients and 153 healthy controls obtained in 1993 or 1998-99. Enteroaggregative, enteropathogenic, and diffusely adherent phenotypes were observed in E. coli isolates from both AIDS patients and controls, but cytotoxic phenotypes were only isolated from the AIDS patients. There was no evidence of seasonality in the frequency of isolation, and there was no evidence of long-term carriage. Light and electron microscopy of distal duodenal biopsies did not reveal any bacteria closely associated with the brush border. Isolates were less susceptible to amoxycillin, tetracycline, and sulfonamides than to newer antibiotics. Enterovirulent E. coli appear to contribute to intestinal disease in AIDS patients in Zambia but asymptomatic carriage is common. Antibiotic trials should be carried out.