Clonal relationship of Escherichia coli biofilm producer isolates obtained from mastitic milk.

Escherichia coli is capable of producing several virulence factors involved in the pathophysiology of bovine mastitis. Cell surface structures such as flagella, pili, and other outer membrane adhesins are considered essential for biofilm formation on abiotic surfaces. The aim of this study was characterize the molecular profile of E. coli isolates obtained from mastitic milk by using the technique of pulsed-field gel electrophoresis (PFGE) and evaluating results within the pulsetypes formed with the presence of virulence genes involved in biofilm production. Twenty-seven E. coli biofilm-producing isolates were obtained from mastitic milk samples belonging to Brazilian Agricultural Research Corporation; these samples were analyzed by PFGE. We identified 9 (I to IX) different phylogenetic groups with a similarity of 90% and observed the presence of fimA (large subunit of the fimbriae type 1) and csgA gene (large subunit of curli fimbriae) in all isolates. Sixteen isolates had the gene fliC (flagellin). Evaluation of the genetic profile carried out through the PFGE showed that the bacteria do not share the same origin. It was not possible to associate the biofilm production capacity with the presence or absence of related genes. Therefore, strains of environmental mastitis-causing E. coli present different pathotypes.