Subtypes of intimin among non-toxigenic Escherichia coli from diarrheic calves in Brazil.

One hundred and five strains of Escherichia coli that were isolated from calves with diarrhea in the state of São Paulo, Brazil, and were negative for enterotoxins and cytotoxins, were examined for the eae gene. Four (3.8%) strains were positive by polymerase chain reaction (PCR) and were shown to produce intimin by using Western blot with specific antiserum against the conserved N-terminal region of intimin. Subtyping of the intimins was done by PCR with specific primers and by Western blot with specific antisera against the C-terminal variable region of the protein. Three of these isolates (O?:H11, O26:H-, O123:H1) produced the beta subtype of intimin, and the 4th (0103:H2) produced intimin that was not typable. The 0103:H2 and the O26:H-isolates adhered to HEp-2 cells with diffuse adherence and localized-like adherence patterns, respectively. The other strains did not adhere to HEp-2 cells. To our knowledge, this is the first report of the occurrence of a subtype of intimin described for human enteropathogenic E. coli among bovine diarrheogenic E. coli. It is also the first report from Brazil demonstrating the presence of bovine E. coli harboring the eae gene.