Evaluation of oxacillin and cefoxitin disks for detection of resistance in coagulase negative staphylococci

Memórias do Instituto Oswaldo Cruz

Ana Lúcia Souza Antunes¹  Carina Secchi²  Keli Cristine Reiter²  Leandro Reus Rodrigues Perez²  Ana Lúcia Peixoto De Freitas²  Pedro Alves D'azevedo² 

[1] ,Fundação Faculdade Federal de Ciências Médicas de Porto AlegrePorto Alegre RS

关键词: coagulase negative staphylococci;    mecA gene;    methicillin resistance;    cefoxitin;    susceptibility tests;   

DOI  :  10.1590/S0074-02762007005000078

来源: SciELO

【 摘 要 】

Coagulase-negative Staphylococcus spp. was considered nonpathogenic until the emergence of multiresistance and the demonstration of their participation as infectious agents. In Brazil, oxacillin resistance may be present in over 80% of isolates, and the Clinical and Laboratory Standards Institute standardized a disk-diffusion method to predict this resistance in Staphylococcus. The aim of this study was to evaluate the variability among commercial disks of oxacillin (1 µg) and cefoxitin (30 µg) widely used in clinical laboratories of microbiology, compared with mecA gene and minimum inhibitory concentration (MIC) of oxacillin. The use of oxacillin and cefoxitin disks simultaneously allowed the detection of important differences, particularly, in less frequent species such as S. cohnii, S. haemolyticus, S. saprophyticus, and S. sciuri. Disks of cefoxitin of the brand 2 displayed good correlation with the mecA gene (98.7%) and oxacillin MIC (97.8%), while major discrepancies were observed using disks of brand 1. One of the critical points in the diffusion disk test is the quality of the disks: the use of better quality disks associated with molecular methods lead to better results to define the best antibiotic therapy.

【 授权许可】

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