SURVEY OF CLINICAL ISOLATES OF DIARRHEOGENIC ESCHERICHIA-COLI - DIFFUSELY ADHERING ESCHERICHIA-COLI STRAINS WITH MULTIPLE ADHESIVE FACTORS

A total of 335 Escherichia coil strains were isolated from sporadic ca ses of aqueous diarrhoea in patients hospitalized in Clermont-Ferrand, France, during 1991 and 1992. Many of these strains belonged to the d iffusely adhering E. coil (DAEC) group, since 51 of them (15.2%) hybri dized with the daaC probe corresponding to the accessory gene of the F 1845 adhesin and 13 (3.9%) with the AIDA-I (adhesin involved in diffus e adhesion-I) structural gene. The other pathogenic E. coil groups wer e weakly represented: 0.6% (2 strains) of enterotoxigenic E. coil (ETE C), 0.6% (2 strains) of enterohaemorrhagic E. coil (EHEC) and 3.9% (13 strains) of enteroaggregative E. coil (EAggEC). Neither enteropathoge nic E. coli (EPEC) nor enteroinvasive E. coil (EIEC) were isolated in our study period. Among the DAEC strains studied, we described two maj or surface proteins of 16 and 29 kDa. We showed that the 16-kDa protei n (CF16K) was involved in adhesion in vitro to Caco-2 and HEp-2 cells. Pretreatment of bacteria with anti-CF16K serum or of Caco-2 cells wit h purified CF16K greatly decreased the adhesion of the E. coil CF1085 strain producing the CF16K protein to both cell types. The CF16K adhes ive factor was found in 9.5% (33 strains) of the 335 E. coil strains s tudied by colony immunoblot assays with anti-CF16K serum. Twelve strai ns producing CF16K hybridized with the daaC probe, indicating that the CF16K is not related to the Dr family adhesins which recognized the D r blood group antigen as receptor. The 29-kDa protein, isolated from 9 strains out of the 335 studied (5.1%), was identified as the CS31A an tigen by Western blot assay using anti-CS31A serum and by hybridizatio n experiments with a CS31A DNA probe. This antigen is routinely observ ed in septicaemic or enterotoxigenic bovine E. coil strains. We showed that a single diarrhoeogenic E. coil strain could harbour at least tw o adhesive factors, since 36% of CF16K E. coil strain producers and 68 .4% of CS31A E. coil strain producers hybridized with the daaC DNA pro be.