Abstract:
scherichia coli strains isolated from faecal specimens of 108 Ethiopian patients with acute watery diarrhoea (n = 30), acute bloody (n = 9), and persistent (n = 25) diarrhoea, and from 44 patients who recently had recovered from diarrhoea were analyzed for the presence of virulence factors using DNA probes, and for adhesion to HeLa cells. Eighty-two patients were under five years of age. Enterotoxigenic E.coli (ETEC) were most frequently isolated (63 patients, 58%). Eighteen of the ETEC strains also hybridized with probes for EPEC adherence factor (EAF) and Enteroaggregative (EAgg) adherence. Enteroaggregative E. coli (EAggEC) were more frequently isolated than EAF positive E.coli, and more frequently from patients with persistent diarrhoea (10/25) than from patients with acute diarrhoea (11/39). In total, 103 of the patients harboured faecal E. coli which hybridized with one or more of the virulence probes. Haemagglutination of one or more erythrocyte species was expressed by 65/70 strains. Using monoclonal antibodies to Colonization Factor Antigen I and Coli Surface antigens 1-5, only 18/66 strains were found to produce one or more of these adhesions and no more than 15 of 43 ETEC strains were agglutinated by the antisera to these adhesins. Forty-nine strains adhered to HeLa cells in autoaggregative (23 strains), localized (17 strains) or diffuse (9 strains) pattern. The study shows that E.coli strains carrying genes for the different virulence factors are prevalent in Ethiopia. Testing for the presence of these virulence factors, as well as for putative colonization factor antigens, should be included in epidemiological studies in this area.