MODELO DE EXCREÇÃO DE CEPAS DE ESCHERICHIA COLI RESISTENTES A ANTIMICROBIANOS EM UMA COORTE DE BEZERROS E SUAS RESPECTIVAS MÃES EM UMA FAZENDA DE LEITE BRASILEIRA.

B. LINO, C.M. MARIN, J.

Rectal fecal samples were collected three times over an eight-month period from five pars of calves and their dams at the same farm, and screened for Escherichia coli resistance to eleven antimicrobial agents. An increase in the number of antimicrobial-resistant isolates was documented in the third collection either in calves and dams, though the increase was higher among calves. A statistically significant increase in the antimicrobial resistance was detected to tetracycline among the calves, and to amoxicillin+clavulanic acid and amikacin among the dams. Careful follow-up of the shedding of E. coli resistant isolates in feces is important, because the use of fresh bovine feces (manure) in land application is usual in Brazil, what could increase the risk of dissemination of antibiotic resistant genes in the environment. KEY-WORDS: Escherichia coli. Antibiotic resistance. Calve. Dams.