Identificação e perfil de resistência a Antibióticos de bactérias isoladas de leite cru no sul de Minas Gerais

Abstract

This research evaluated the diversity and antibiotic resistance profile (tetracycline, novobiocin, norfloxacin, lincomycin, erythromycin, cefuroxime, streptomycin, chloramphenicol and ampicillin) of bacteria isolated from raw milk samples obtained from 16 small farms in the region of dairy cattle in southern Minas Gerais/ Brazil. The Gram-negative bacterial strains were identified by identification kits Bactray I, II and III, prior oxidase tests. Staphylococci identification was carried out by biochemical tests following Bergeys’s manual; and the Enterococcus were identified by the kit API 20 Strep. To determine the resistance profile, we employed the method of disc diffusion according CLSI (2008). The strains were classified in resistant, intermediate and susceptible according inhibition zones and its index of multiple resistance (MAR) was obtained. We identified the following species of genus Staphylococcus: S. caseolyticus, S. aureus, S. hyicus, S. chromogenes and S. carnosus. In the genus Enterococcus were identified E. durans, E. faecium and E. faecalis. The members of the family Enterobacteriaceae isolated were Escherichia coli, Enterobacter aerogenes, Klebsiella oxytoca, Klebsiella ornithinolytica, Yersinia enterocolitica, Yersinia pseudotuberculosis and Morganella morganii. Among the Gram-negative oxidase- -positive were identified Alcaligenes faecalis, Alcaligenes denitrificans, Burkholderia cepacia and Pseudomonas pseudoalcaligenes. In general the isolates tested presented MAR index more than 0.2, indicating the multidrug resistance. These results suggest a possible role of the antibiotic indiscriminate application in the dairy farming of this region, leading to selecting multi-resistant bacteria.