Virulence Genes in Isolates of Escherichia coli from Samples of Milk and Feces from Dairy Cattle

Abstract

The aim of this work was to determine if Escherichia colt isolates carrying the virulence genes eae and eltB and exhibiting the Ehly phenotype are present in feces and milk samples from healthy dairy cattle on farms. Isolates from calves showed a statistically higher prevalence of eae and eltB compared with isolates from older animals. The other factors tested (stx(1), stx(2), and Ehly) were not statistically different between the two groups. Two isolates originating from calf feces were identified as serotype O157:H7; one of these isolates carried six, and eae, the other stx2 and eae. E. colt isolated from milk contained stx(1), stx(2), and eltB. The results show that feces or milk from healthy dairy cattle may contain E. coli pathotypes that express virulence genes, indicating that these materials have zoonotic potential. The results also reinforce the idea that host age can influence the dynamics of virulence genes in E. coil from cattle.