Caracterização de Staphylococcus do grupo sciuri e analise fenogenotípica da resistência à oxacilina em isolados de roedores e equinos do Instituto Biológico do Exército

Abstract

Oxacillin/methicillin-resistance in Staphylococcus is related to the integration of SSCmec, containing the mec complex, in the bacterial chromosome. The mecA gene codifies a variant of PBP2, termed PBP2a or PBP2’, whose affinity with the beta-lactamic antibiotics is very low. Complex mec contains mecA and its regulatory genes mecR1 and mecI. Its origin is still unknown, although evidences support that it is related to coagulase-negative staphylococci, once mecA and a homologue gene, pbpD, were both detected in Staphylococcus sciuri species group. The present work evaluated 210 samples of skin and ear swabs from rodents and 60 nasal swabs from equines of Army Biologic Institute, Rio de Janeiro. Pheno- and genotypic results were concordant for 59,52% (25/42) and 78,57% (11/14) S. lentus and S. sciuri isolates, respectively. The phenotypic antimicrobial resistance pattern was evaluated and correlated to the detection of mecA and pbpD genes. Also, mecA sequences from sciuri group strains were compared to others species in order to evaluate the degree of similarity among them. Although all S. sciuri isolates tested positive for pbpD, no correlation was observed with antimicrobial resistance for isolates that presented only mecA homologue On the other hand, isolates tested positive for mecA gene also presented phenotypic resistance in at least one assay. The alignment of the mecA gene showed that the nucleotide sequences were sorted into 2 different groups, one comprising the bovine strains and the other containing human and equine strains.