Comparison of cefoxitin and moxalactam disc diffusion methods for detection of methicillin resistance in coagulase-negative staphylococci

Objective:To compare cefoxitin and moxalactam 30 μg disc diffusion (DD) methods in detecting methicillin-resistance in coagulase-negative staphylococci (MRCoNS).Methods:Two hundred and fourteen strains of clinically isolated coagulase-negative staphylococci (CoNS) were tested by cefoxiti and moxalactam 30 μg DD methods,and the result was compared with that by penicillin-binding protein (PBP2a) and polymerase chain reaction (PCR) detection.Results:One hundred and eighty-six strains of MRCoNS were identificated by PCR and PBP2a) latex agglutination test.The sensitivity/specificity of cefoxitin and moxalactam were 100.0%/100.0% and 90.3%/87.1%,respectively.The results of two tests were consistent in 99.4% of the isolates.Conclusions:Moxalactam 30 μg DD method has the same sensitivity and similar specificity with cefoxitin DD method in detecting CoNS.Two DD methods show a similar intrinsic performance in detecting methicillin resistance in CoNS.