Molecular Detection of Panton Valentine Leukocidine Gene among Beta-lactamase Producing Staphylococcus aureus Isolated from Clinical Samples in Ondo State, Nigeria

Background: In recent time Staphylococcus aureus has been implicated not only in hospital-acquired but also in community-acquired infections. Some clonal types of S. aureus that produce β-lactamase have evolved. Panton-Valentine leukocidine (pvl) gene among β-lactamase-producing S. aureus from clinical samples in Ondo State, Nigeria has not been reported; hence the objective of this study.

Methods: Clinical samples were collected from secondary and tertiary hospitals in the study area. Amplification and detection of nuc gene was used to confirm the identity of the isolates while polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) of the coagulase gene and pulsed field gel electrophoresis (PFGE) were further carried out on the isolates. Production of β-lactamase was also detected in the isolates using iodometric method while disc diffusion method was used to determine the sensitivity of the isolates to selected antibiotics. The presence of pvl genes among the β-lactamase producers was detected by PCR.

Results: A total of 58 isolates were biochemically confirmed as S. aureus out of which only 21 were β-lactamase producers. Out of the 21 β-lactamase-producing isolates 90.48% (n=19) possessed the nuc gene. Molecular screening of the isolates showed that only one out of the isolates did not possess the coagulase gene. Nine out of the isolates possessed pvl gene among β-lactamase-producing S. aureus. All the isolates were resistant to penicillin and tetracycline while 33.3% and 19.04% were resistant to chloramphenicol and erythromycin respectively. Oxacillin, cefoxitin, clindamycin and fusidic acid completely inhibited the growth of the isolates. Gentamicin and ciprofloxacin were effective on only 4.76% of the isolates.

Conclusion: The prevalence of oxacillin resistance among S. aureus is very low.