Resistência a antimicrobianos em Staphylococus aureus isolados de gado de leite

• Autor(a) principal: Silva, Carla Cilene Matos
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1534
• topic: Mastite; Resistência; Antimicrobianos; Staphylococus aureus; Mastitis; Resistance; Antimicrobial; Staphylococus aureus; CNPQ::CIENCIAS BIOLOGICAS::MICROBIOLOGIA::MICROBIOLOGIA APLICADA::MICROBIOLOGIA INDUSTRIAL E DE FERMENTACAO

The genetic diversity among Staphylococcus aureus strains isolated from bovine mastitis cases in the Zona da Mata Region, Minas Gerais, Brazil, was studied along with the strains resistance to penicillin, oxacillin, amipicillin and also to tylosin. DNA amplification and sequecing of the 16S rRNA encoding region were performed for phylogenetic analysis. Antimicrobial resistance profiles were determined by Minimal Inhibitory Concentration measurements (MIC). The genes blaZ and mecA, confering resistance to β-lactams, and the gene ermC, confering resistance to macrolide, were detected by PCR amplification with specific primers. 16S rDNA sequences originated from S. aureus isolated from cows with clinical, subclinical or chronic mastitis in different regions of Zona da Mata displayed genetic diversity among themselves as demonstrated by nucleotide alignment and reconstruction of phylogenetic trees. Two of the nine bovine isolates from subclinical mastitis displayed closer relatedness with S. aureus originated from human clinical specimens than to the others of bovine origin. Strains isolated from cows with chronic mastitis were less related to S. aureus originated from human clinical specimens. Strains from crhonic mastitis originated from the same herd are phylogenetically very close and also group with S. aureus from human origin. Among all the strains, 48% were sensitive to ampicillin and penicillin, 97% were sensitive to oxacillin. The genes blaZ and mecA were present in 16% and 13%, respectively, among the 31 strains. Among strains resistant to ampicillin and penicillin, 31% and 25%, presented blaZ and mecA, respectively. S. aureus 226/C, originating from clinical mastitis, was determined to have the MRSA phenotype. Only 6,5% were resistant to tylosin and only one S. aureus strain, 247/R isolated from chronic mastitis, presented the ermC gene. Phylogenetic analysis of the blaZ sequences revealed close relatedness among all the strains from the region; however a difference from the human originated S. aureus was observed. The genes ermC found and sequenced are also different. Genetic diversity was thus demonstred among S. aureus strains isolated from cows with mastitis and among the prevalent antimicrobial resistance genes.