Evaluation of the accuracy of various phenotypic tests to detect oxacillin resistance in coagulase-negative staphylococci

• Autor(a) principal: Perez,Leandro Reus Rodrigues
• Data de Publicação: 2008
• Outros Autores: d'Azevedo,Pedro Alves
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Brazilian Journal of Infectious Diseases
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1413-86702008000300009
• topic: Oxacillin; cefoxitin; CoNS

In this study, we determined the accuracy of phenotypic tests (cefoxitin agar dilution, 30µg-cefoxitin and 1µg-oxacillin disks) to detect the oxacillin resistance/mecA gene among coagulase-negative staphylococci (CoNS) isolates. The presence of the mecA gene was detected by PCR technique (gold standard). A total of 176 CoNS isolates from blood of hospitalized patients were evaluated. Of these, 138 (78.4%) harbored the mecA gene. Using 30µg-cefoxitin and 1µg-oxacillin disks we obtained 100 and 98.3% accuracy, respectively. In addition, when cefoxitin was used as marker in an agar dilution method, the higher accuracy (99.4%) was established with 8mg cefoxitin per mL breakpoint. Thus, despite of the agar dilution method using cefoxitin as a marker not being standard for this detection, our results suggested that it is an excellent alternative to detect the oxacillin resistance/mecA gene among CoNS isolates.