Fatores de virulência em amostras de Escherichia coli isoladas de mastite bovina

Abstract

Bovine mastitis is considered one of the most important and costly infectious diseases of dairy cattle. Among the bacteria associated with mastitis, Escherichia coli is one of the main agents that causes intramammary infection in dairy herds and is associated with severe clinical signs. The objective of this study was to classify isolates of E. coli in relation to the genetic group (B1, B2, A and D) and to evaluate the frequency of the virulence genes fliC, F17, escN, lpfA and icm of importance for E. coli mammary in 69 bovine mastitis isolates and 31 environmental isolates (faeces) collected in different dairy herds in the region of Lavras - MG. According our results, the B1 genetic group prevailed with 56.52% of the mastitis isolates followed by the B2 group with 39.13%. Eight virulence profiles were defined according to the frequency of the genes studied. Profile 5 was the most frequent, highlighting the fliC and escN genes with prevalence of 73.91% and 55.07% of the mastitis isolates while the lpfA gene was detected in 17.39%. The icm and F17 genes were not detected. The manifestations resulting from intramammary infections caused by E. coli are determined by the expression of different virulence factors, with the fliC, escN and lpfA genes being the most relevant in this study.