RESUMO
Panton-Valentine leukocidin [PVL] is a biocomponent cytotoxin and assumed S. aureus virulence factor that has been associated with skin and soft tissue infections together with more severe manifestations including necrotising pneumonia. PVL has been strongly associated with emergence of community acquired methicillin-resistant S. aureus [CA-MRSA]. Objective: The aim of the current study is to determine whether carriage of PVL could be used as surrogate marker for CA-MRSA strains using rapidreal time PCR. Methods: The study was conducted on 92 community-acquired Staphylococcus aureus isolates which caused different types of infections and isolated from inpatients and outpatients attending different departments at Al-Zahraa Hospital. All isolates were identified by colony morphology on mannitol salt agar medium, Gram stain, positive reaction for catalase, coagulase and DNAase. Biochemical and antibiogram susceptibility testing were performed using walkaway MIC plates. MRSA strains were tested for penicillin binding protein 2a [PBP2a] using Mastalex Kit and PVL gene by real time polymerase chain reaction [RT-PCR] . Results: Out of 92 community-acquired Staphylococcus aureus isolates 34 [36.96%] were MSSA, while 58 [63.04%] were MRSA strains. Detection of PBP2a by Mastalex Kit was false negative in 6 [10.3%] of MRSA isolates. Detection of PVL gene by real time PCR was positive in only 23 isolates [39.7%]. Antimicrobial susceptibility testing revealed that all MRSA strains were resistant to lactam, cephalosporin, Carbapenems antibiotics and 91.4% of MRSA strains were resistant to tetracycline, while 70.7% were resistant to aminoglycosides and 5.2% were resistant to vancomycin. In Conclusion: During recent years, methicillin-resistant Staphylococcus aureus continues to be a major cause of both health care-associated and community-associated infections. Rapid and reliable detection with implementation of infection control measures is essential in limiting the spread of this organism. In this study, it was found that carriage of PVL cannot be used as a sole marker for CAMRSA and further studies are required to find a reliable marker or combination of markers to facilitate the recognition of CA-MRSA strains