Caracterização molecular e fenotípica de Escherichia coli isolada de surto de diarreia em bezerros

Abstract

Escherichia coli is a major cause of diarrhea in newborn calves and the intensification of cattle raising has increased its incidence. The objective of this study is to characterize the molecular and phenotypic characterization of the E. coli sample isolated from a diarrhea outbreak in neonatal calves in the western region of São Paulo, Brazil, in 2016. The E. coli samples were analyzed by PCR for presence of the following virulence genes: cnf1, cnf2, lt1, lt2, sta, stx1, stx2, F5 (k99), F41. HeLa cell culture tests were performed and great invasive power was observed in these samples. Antimicrobial drug susceptibility testing revealed resistance to multiple drugs. The analysis of gene sequencing revealed that the sample in question presents the fdeC gene and absence of the other characteristic genes of the E. coli categories already described. Pathological examination revealed septicemia, with passive congestion of the liver and kidney with multifocal hepatocyte necrosis and inflammation of the intestinal loop. These data indicate that this is a new category of E. coli here called “calf invasive E. coli” - CIEC. According to the literature, the role of the fdeC gene is related to the invasive capacity of pathogenic E. coli samples, while the FdeC protein has been described as a strong candidate for use as an antigen for the construction of a broad-spectrum E vaccine. coli of intestinal and extra - intestinal origin.