Rapid Detection of Methicillin-Resistant Staphylococcus aureus by Multiplex PCR

ABSTRACT

Staphylococcus aureus continues to be the main cause of surgical site infections. Recently, methicillin-resistant S. aureus (MRSA) has been known to be resistant to many kinds of antibiotics and causes the problem of neonatal nosocomial infection. Antibiotic sensitivity tests which have been routinely used to detect MRSA in the laboratory depend on the culture conditions. Therefore it is necessary to develop a new method based on a molecular biological technique in order to overcome these problems. We report the development of a multiplex PCR protocol for the diagnosis of staphylococcal infection. The protocol was designed to i) detect any staphylococcal species to the exclusion of other bacterial pathogens (based on primers corresponding to staphylococcal-specific regions of the 16S rRNA genes), ii) provide an indication of the likelihood that the Staphylococci present in the specimen are resistant to oxacillin (based on the amplication of the mecA gene, encoding penicillin-binding protein 2'(PBP-2'), which is known to confer resistance to the bacteriostatic action of methicillin). In this study, 67 S. aureus strains were isolated from the neonatal intensive care unit and general neonatal nursery at Pusan National University Hospital, Busan, Korea, between January and July 2003. Methicillin resistance was tested by the oxacillin disk diffusion method and the MIC method. We performed the multiplex PCR to amplify the mecA gene, encoding PBP-2'. We tested it by multiplex PCR and compared the results with the antimicrobial susceptibilities. Different results were obtained from 2 MRSA (4.65%), suggesting that the PCR method should be performed at the same time for a more accurate clinical test of MRSA