Prevalence of Panton-Valentine Leukocidin Gene among Community Acquired<i>Staphylococcus aureus</i>: A Real-Time PCR Study

Abstract

Panton-Valentine leukocidin (<i>luk-pv</i>) is a cytotoxin that causes leukocyte destruction and tissue necrosis. The aim of this study was to determine the prevalence of the <i>pv1</i>, <i>mecA</i>, and <i>nuc</i> genes in <i>Staphylococcus aureus</i> isolates obtained from anterior nares and superficial infection sites of skin in a slum population of West Bengal, India. Expression level of <i>pv1</i> gene was also analysed. Twenty-two <i>S. aureus</i> strains were isolated, and phenotype and genotype specific examinations for <i>S. aureus</i> isolates were carried out. Molecular identification was done by PCR using species-specific 16S rRNA primer pairs and finally 22 isolates were found to be positive as <i>S. aureus</i>. The antibiotic responsiveness of all these isolates and the minimum inhibitory concentration (MIC) of MRSA isolates were determined using the broth dilution method with vancomycin. Antibiogram analysis of isolated <i>S. aureus</i> strains with respect to different antimicrobial agents revealed antibiotic resistance ranging from 27 to 91%. The results of MIC for vancomycin showed 95% of strains to be VSSA and 5% to be VISA. 68% isolates were resistant to methicillin. All the isolates were subjected to detection of <i>pv1, mec</i>A, and <i>nuc</i> genes, and 9%, 68%, and 27% were found to harbour <i>pvl, mec</i>A, and <i>nuc</i> genes, respectively. All the MRSA strains produced high to moderate levels of biofilm. <i>pvl</i> gene expression was carried out <i>in vitro</i> by Real-Time PCR. The low ∆Ct value (0.493) was indicative of high expression of <i>pvl</i> in one <i>S. aureus</i> strain. Thus, detection of <i>pvl</i> gene in community acquired <i>S. aureus</i> indicates the emergence of pathogenic <i>S. aureus</i> in community setup in the studied region. The existing exploration is extremely imperative and informative for the high level multi-drug resistant <i>S. aureus</i> infections inclusive of MRSA.