Isolation from a sheep of an attaching and effacing Escherichia coli O115:H- with a novel combination of virulence factors
Cookson, A. L., Hayes, C. M., Pearson, G. R., Roe, J. M., Wales, A. D. and Woodward, M. J. (2002) Isolation from a sheep of an attaching and effacing Escherichia coli O115:H- with a novel combination of virulence factors. Journal of Medical Microbiology, 51 (12). pp. 1041-1049. ISSN 0022-2615
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Official URL: http://jmm.sgmjournals.org/content/51/12/1041.abst...
Attaching and effacing (AE) lesions were observed in the caecum, proximal colon and rectum of one of four lambs experimentally inoculated at 6 weeks. of age with Escherichia coli O157:H7. However, the attached bacteria did not immunostain with O157-specific antiserum. Subsequent bacteriological analysis of samples from this animal yielded two E. coli O115:H- strains, one from the colon (CO) and one from the rectum (RC), and those bacteria forming the AE lesions were shown to be of the O115 serogroup by immunostaining. The O115:H(-)isolates formed microcolonies and attaching and effacing lesions, as demonstrated by the fluorescence actin staining test, on HEp-2 tissue culture cells. Both isolates were confirmed by PCR to encode the epsilon (epsilon) subtype of intimin. Supernates of both O115:H- isolates induced cytopathic effects on Vero cell monolayers, and PCR analysis verified that both isolates encoded EAST1, CNF1 and CNF2 toxins but not Shiga-like toxins. Both isolates harboured similar sized plasmids but-PCR analysis indicated that only one of the O115:H- isolates (CO) possessed the plasmid-associated virulence determinants ehxA and etpD. Neither strain possessed the espP, katP or bfpA plasmid-associated virulence determinants. These E. coli O115:H- strains exhibited a novel combination of virulence determinants and are the first isolates found to possess both CNF1 and CNF2.