Search

Fifty‐six CNF1‐producing Escherichia colistrains isolated from cattle with diarrhea or septicemia were screened by PCR for the detection of pap, sfa, afa, clpG, or f17 adherence factor and EAST 1 toxin genes. All the isolates were pap‐positive, in accordance with the close association of pap, CNF1 and α‐hemolysin genes observed on human and porcine E. coli. Only the gene encoding the P adhesin of class III (PrsG) was detected. Genes encoding CS31A antigen (71%) and S fimbriae (34%) (but not Afa or F17) were detected among the bovine isolates. E. coliproducing both CNF1 and plasmid‐encoded CS31A is a new example of association between bacterial clones and plasmid‐mediated virulence factors. The EAST 1 toxin‐encoding gene was detected on 66% of the CNF1‐producing isolates but was linked to CS31A rather than to CNF1. These results suggest a close association between EAST 1 toxin and the adherence factor CS31A among pathogenic bovine E. coli.

Forty-two Escherichia coli strains producing surface antigen CS31A isolated from bovine infections were characterized with respect to OKH serotypes, outer membrane protein (OMP) elelctrophoretic patterns, allozymes for esterases A, B, C, I and biotypes. A large majority of the strains could be clustered in a limited number of groups of clonally related strains with diverse O serogroups. CS31A producing Escherichia coli strains thus appear to have a common genetic background and are representative of an important part of bovine pathogenic Escherichia coli.

Bovine and porcine enterotoxigenic and non-enterotoxigenic Escherichia coli isolates from France, Canada, and India were characterized with respect to serogroup and production of fimbrial antigens CS31A and F165. Of 231 bovine isolates from the 3 countries, 20.5% produced CS31A alone, 17.7% produced F165 alone, and 17.3% produced both CS31A and F165. On the other hand, of 84 porcine isolates from Canada, 1.2% produced CS31A alone, 14.3% produced F165 alone, and no isolate produced both CS31A and F165. CS31A was found together with F5 (K99) in 7 of 16 bovine enterotoxigenic E. coli isolates of serogroups 08, 09, 020, and 023, but was not found in any of 20 F4 (K88)- or 5 F6 (987P)-positive porcine enterotoxigenic E. coli isolates. F165 was not found in enterotoxigenic E. coli. Among non-enterotoxigenic isolates, CS31A and F165 were mainly associated with serogroups 08, 09, 011, 015, 017, 023, 025, 078, 0101, 0115, 0117, 0141, and 0153.

One hundred Escherichia coli isolates from human septicemia were characterized with respect to O serogroups 1, 2, 4, 6, 7, 8, 15, 18, 75 and 78, α-hemolysin, carboxylesterase B typing, cytotoxic necrotizing factor, F165 and CS31A fimbrial antigens, aerobactin production, colicins, and antibiotic sensitivity. A factorial analysis of correspondence and x2 tests indicated that most of E. coli isolates belonging to the studied O serogroups were positive for the virulence factors or markers α-haemolysin, carboxylesterase B2 type, cytotoxic necrotizing factor, F165 fimbrial antigen and were antibiotic-sensitive (Group I). These characteristics differentiated them from E. coli isolates from other O serogroups which were genrally antibiotic resistant and negative for the cited virulence factors and markers (Group II). Aerobactin and colicin production did not differentiate the two E. coli groups. E. coli O serogroups 4 and 6 were highly rpresented in group I and were responsible for most of the differences between the two groups

The clonal relationship of thirty E. coli strains of 0 antigen serotype 06 isolated from human, dog, pig or cow infections were investigated. Two main clones with serotypes 06:H1 or 06:H31, H− were identified. Isolates from humans, dogs, pigs and cows were found in both clones, indicating that animals are a possible source for human extraintestinal Escherichia coli strains. Two human ETEC (06:H16) and two pig isolates (06:H10) were not related to the 06:H1 or 06:H31, H−E. coli clones.

Fifty-six CNF1-producing Escherichia coli strains isolated from cattle with diarrhea or septicemia were screened by PCR for the detection of pap, sfa, afa, clpG, or f17 adherence factor and EAST 1 toxin genes. All the isolates were pap-positive, in accordance with the close association of pap, CNF1 and α-hemolysin genes observed on human and porcine E. coli. Only the gene encoding the P adhesin of class III (PrsG) was detected. Genes encoding CS31A antigen (71%) and S fimbriae (34%) (but not Afa or F17) were detected among the bovine isolates. E. coli producing both CNF1 and plasmid-encoded CS31A is a new example of association between bacterial clones and plasmid-mediated virulence factors. The EAST 1 toxin-encoding gene was detected on 66% of the CNF1-producing isolates but was linked to CS31A rather than to CNF1. These results suggest a close association between EAST 1 toxin and the adherence factor CS31A among pathogenic bovine E. coli.