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  • Author or Editor: Etienne Jacquemin x
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Summary

Two hundred ninety-six Escherichia coli isolates from feces or intestines of calves with diarrhea were hybridized with 7 gene probes. One probe (the eae probe) was derived from The eae gene coding for a protein involved in the effacement of the enterocyte microvilli by the group of bacteria called attaching and effacing E coli (aeec), and 2 probes were derived from genes coding for the Shiga-like toxins (slt) 1 and 2 produced by the verocytotoxic E coli (vtec). The other 4 probes were derived from dna sequences associated with the adhesive properties of enteroadherent E coli (eaec) to cultured cells (the eaf probe for the localized adherence pattern, probes F1845 and aida-1 for the diffuse adherence pattern, and the Agg probe for the aggregative adherence pattern). Hybridization results for the eae probe were in agreement, for all but 1 of the 8 isolates, with previously published phenotypic results of microvilli effacement. The latter was previously reported as effacing the microvilli of calf enterocytes, but was eae probe-negative. Two classes of isolates hybridized with the eae probe. Members of a first class (60 isolates) additionally produced a positive signal with 1 or both of the slt probes (vtec-aeec isolates). Isolates hybridizing with the eae and the slt1 probes were the most frequent: 56 isolates (ie, 93% of all vtec-aeec). Members of the second class (10 isolates) failed to hybridize with either slt probe (non-vtec-aeec isolates). Most isolates of these 2 classes belong to only 4 serogroups: O5, O26, O111, and O118. In addition to these 2 aeec classes, a vtec class (20 isolates) was observed. Such isolates were positive with 1 or both slt probes, but were negative with the eae probe. All but 1 isolate belonged to serogroups not found among the aeec isolates. Only 7 of all aeec and vtec isolates were positive with the eaf, the F1845, or the aida-1 probe, and none were positive with the Agg probe. On the other hand, 32 non-vtec, non-aeec isolates were positive with the F1845 probe only, 2 were positive with the eaf probe only, and 1 was positive with the aida-1 probe only, thus constituting a possible class of eaec isolates from cattle. The eae gene and the gene coding for the slt1 are, thus, associated in most aeec isolates from cattle. The isolates with other hybridization results (vtec and eaec isolates) need more work to be clearly defined.

Free access
in American Journal of Veterinary Research

SUMMARY

Colony hybridizations with DNA probes for 3 heat-stable (STap, STaH, and STb) enterotoxins and 1 heat-labile (LT) enterotoxin and for 4 adhesins (K99, F41, K88, 987P) were performed on 870 Escherichia coli isolates to determine pathotypes prevalent among enterotoxigenic E coli (ETEC) isolated form cattle in Belginum. One hundred thirty-two E coli isolates (15.2%) hybridized with probes STap, K99, and/or F41. The 5 other probes were not hybridized by E coli isolates. Therefore, only STaP enterotoxin and K99 and F41 adhesins were virulence factors of ETEC isolated from cattle. Two major pathotypes accounted for 95% of the ETEC: STaP+ K99+ F41+ (67.4%) and STaP+ K99+ (27.3%). The last 5% of probe-positive isolates had STaP+ STaP+ F41+, or K99+ F41+ minor pathotypes. Of 12 American ETEC isolates also assayed, 7 were positive with STb and/or 987P probes (pathotypes STap+ STb+ STaP+ 987P+, or STaP+STb+987P+) and may be porcine-rather than bovine-specific enteropathogens. The remaining 5 American ETEC isolates belonged to 3 minor pathotypes (STaP+, STaP+, F41+, and K99+ F41+) also found among Belgian E coli isolates. Such isolates may be derivatives of STaP+ K99+ F41+ or STaP+ K99+ etec after in vivo or in vitro loss of virulence genes and /or non-etec isolates, which have acquired virulence genes by in vivo transfer.

Free access
in American Journal of Veterinary Research