Stx genotypes and antimicrobial resistance profiles of Shiga toxin-producing Escherichia coli strains isolated from human infections, cattle and foods in Brazil.

A total of 107 Shiga toxin-producing Escherichia coli strains (STEC) isolated from different origins in São Paulo, Brazil, and belonging to different serotypes were characterized regarding stx subtypes and susceptibility to antimicrobial agents. Most of the human STEC strains harbored stx1 (85.7%), while stx2, associated or not to stx1, was identified preferentially in the animal and food strains.

Bundle-forming pili and EspA are involved in biofilm formation by enteropathogenic Escherichia coli.

Microcolony formation is one of the initial steps in biofilm development, and in enteropathogenic Escherichia coli (EPEC) it is mediated by several adhesins, including the bundle-forming pilus (BFP) and the EspA filament. Here we report that EPEC forms biofilms on plastic under static conditions and a flowthrough continuous culture system. The abilities of several EPEC isogenic mutants to form biofilms were assessed.

Enteroaggregative Escherichia coli from humans and animals differ in major phenotypical traits and virulence genes.

Enteroaggregative Escherichia coli (EAEC) is characterized by the expression of the aggregative adherence pattern to cultured epithelial cells. In this study, we determined the phenotypic and genotypic relationships among 86 EAEC strains of human and animal (calves, piglets and horses) feces. Serotypes and the presence of EAEC virulence markers were determined, and these results were associated with ribotyping.

Clonal relationships among avian Escherichia coli isolates determined by enterobacterial repetitive intergenic consensus (ERIC)-PCR.

Forty-nine avian Escherichia coli isolates isolated from different outbreak cases of septicemia (24 isolates), swollen head syndrome (14 isolates) and omphalitis (11 isolates), and 30 commensal isolates isolated from poultry with no signs of illness were characterized by enterobacterial repetitive intergenic consensus (ERIC)-PCR technique and their serotypes were determined. The ERIC-PCR profile allowed the typing of the 79 isolates into 68 ERIC-types and grouped the isolates into four main clusters (A-D), with the omphalitis isolates being grouped with the commensals and separated from the septicaemia and swollen head syndrome. These results indicate that ERIC-PCR is a technique that could replace other molecular characterization techniques such as random amplification of polymorphic DNA (RAPD)-PCR and restriction fragment length polymorphism (RFLP), reinforce previous observations that omphalitis isolates are just opportunistic agents, and are consistent with many reports that specific genotypes are responsible for causing specific diseases.