VIRULENCE PROPERTIES OF ESCHERICHIA-COLI ISOLATED FROM ETHIOPIAN PATIENTS WITH ACUTE OR PERSISTENT DIARRHEA

Escherichia coli strains isolated from faecal specimens of 108 Ethiopi an patients with acute watery diarrhoea (n=30), acute bloody (n=9), an d persistent (n=25) diarrhoea, and from 44 patients who recently had r ecovered from diarrhoea were analyzed for the presence of virulence fa ctors using DNA probes, and for adhesion to HeLa cells. Eighty-two pat ients were under five years of age. Enterotoxigenic E.coli (ETEC) were most frequently isolated (63 patients, 58%). Eighteen of the ETEC str ains also hybridized with probes for EPEC adherence factor (EAF) and E nteroaggregative (EAgg) adherence. Enteroaggregative E, coli (EAggEC) were more frequently isolated than EAF positive E.coli, and more frequ ently from patients with persistent diarrhoea (10/25) than from patien ts with acute diarrhoea (11/39). In total, 103 of the patients harbour ed faecal E.coli which hybridized with one or more of the virulence pr obes. Haemagglutination of one or more erythrocyte species was express ed by 65/70 strains. Using monoclonal antibodies to Colonization Facto r Antigen I and Coli Surface antigens 1-5, only 18/66 strains were fou nd 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. For ty-nine strains adhered to HeLa cells in autoaggregative (23 strains), localized (17 strains) or diffuse (9 strains) pattern. The study show s that E.coli strains carrying genes for the different virulence facto rs are prevalent in Ethiopia. Testing for the presence of these virule nce factors, as well as for putative colonization factor antigens, sho uld be included in epidemiological studies in this area.