Molecular characterization of methicillin-resistant Staphylococcus aureus recovered from outpatient clinics in Riyadh, Saudi Arabia

OBJECTIVE: To examine the recovered strains phenotypically, by conventional methods and genotypically by polymerase chain reaction (PCR), for direct detection of Staphylococcus aureus (S. aureus) 16S ribosomal Ribonucleic Acid (rRNA) gene (which serves as an internal control) and mecA gene. Secondly, introduce multiplex PCR targeting at the same time S. aureus 16S rRNA, Panton-Valentine Leucocidin (PVL), and staphylococcal cassette chromosome mec (SCCmec) type IV.

METHODS: Thirty-seven strains of S. aureus collected in 2007 from outpatient clinics in King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia, were tested in the College of Pharmacy phenotypically by conventional methods and genotypically by PCR for direct detection of S. aureus 16S rRNA and mecA genes. All the 37 strains, were tested also by multiplex PCR targeting at the same time S. aureus 16S rRNA, PVL, and (SCCmec) type IV.

RESULTS: Polymerase chain reaction detected all the 37 bacteriologically positive S. aureus (100%) and the mecA gene in all strains phenotypically resistant to methicillin (100%), at the same time it detected the mecA gene in 2 strains phenotypically sensitive to methicillin. Only 3 strains (8.1%) recovered from skin and soft tissue infections were positive for PVL and SCCmec type IV.

CONCLUSION: The PCR assay can be used for rapid detection of S. aureus and mecA gene. At the same time the multiplex PCR assay explained in this study is a rapid, sensitive, and reliable test for direct detection of community-acquired methicillin-resistant S. aureus.