Diversidade genética, fatores de virulência e resistência a antimicrobianos em Streptococcus uberis isolados de mastite bovina

Abstract

Bovine mastitis is a multifactorial disease in whose etiology are involved different agents that can be classified as contagious or environmental. Streptococcus uberis is an important environmental pathogen associated with bovine mastitis, responsible for a large proportion of infections. Despite the incresed importance, the pathogenesis is still unknown. Searches of genetic and molecular characteristics of the pathogen can do much to improve the knowledge about bacterial activity and identify molecules that have definite role in the establishment of infection, to propose effective measures to control and disease prevention. Pulsed-field gel electrophoresis (PFGE) has been used successfully for the purpose of providing information on the epidemiology of S. uberis. Information about antimicrobial susceptibility can be valuable in the election of suitable drugs for the treatment of mastitis by S. uberis. In this study, S. uberis isolated from bovine mastitis in the southern state of Minas Gerais, Brazil, were investigated in order to describe the genetic profile by PFGE and the frequency of important virulence genes of these pathogens, sua, pauA e skc. The results showed a high frequency of the virulence genes and great genetic diversity of S. uberis studied. Also searched was the antimicrobial susceptibility of isolates by determining the minimum inhibitory concentration (MIC). We determined the MIC for 50% and 90% of S. uberis researched to ampicillin, cephalothin, ceftiofur, enrofloxacin, streptomycin, florfenicol, gentamicin, lincomycin, penicillin and tetracycline. It was found elevated levels of resistance to streptomycin and low levels of resistance to other antimicrobials.