Detection ofmecA, femA, andfemBgenes in clinical strains of staphylococci using polymerase chain reaction

Abstract

SUMMARYMecA, a structural gene located on the chromosome ofStaphylococcus aureus, characterizes methicillin-resistantS. aureus(MRSA), andfemAandfemB(fem)genes encode proteins which influence the level of methicillin resistance ofS. aureus. In order to examine effectiveness of detectingmecAandfemgenes in identification of MRSA, the presence of these genes in 237 clinically isolated strains of staphylococci was investigated by polymerase chain reaction (PCR). An amplifiedmecADNA fragment of 533 base pairs (bp) was detected in 100% of oxacillin-resistantS. aureus, in 16·7 % of oxacillin-sensitiveS. aureus, in 81·5% ofS. epidermidis, and in 58·3% of other coagulase-negative staphylococci (CNS). While the PCR product offemA(509 bp) orfemB(651 bp) was obtained from almost all theS. aureusstrains except for five oxacillin-resistant strains (2·5%), neither of these genes were detected in CNS. Therefore, the detection offemAandfemBtogether withmecAby PCR was considered to be a more reliable indicator to identify MRSA by differentiating it frommecA-positive CNS than single detection ofmecA.