Vol 11, Issue 2, 2018 Online - 2455-3891 Print - 0974-2441 ASSOCIATION OF VIRULENCE FACTOR (PANTON–VALENTINE LEUKOCIDIN) WITH MECA GENE IN STAPHYLOCOCCUS AUREUS ISOLATES IN TERTIARY CARE HOSPITAL NILIMA R PATIL, GHORPADE MV* 1 Department of Microbiology, Research Scholar, Krishna Institute of Medical Sciences, Karad, Maharashtra, India. 2 Department of Microbiology, Krishna Institute of Medical Sciences, Karad, Maharashtra, India. Email: mvghorpade611@gmail.com Received: 11 April 2017, Revised and Accepted: 30 October 2017 ABSTRACT Introduction: The pathogenicity of Staphylococcus aureus depends on various bacterial surface components and extracellular proteins. S. aureus expresses a variety of virulence factors, including Panton–Valentine leukocidin (pvl). pvl is a cytotoxin produced by S. aureus that causes leukocyte destruction and tissue necrosis. Despite the presumed importance of pvl as a virulence factor, few data are available on its prevalence among S. aureus isolates in our area. Objectives: This study was aimed to determine the association between mecA gene and virulence genes such as pvl gene in strains of S. aureus and to determine the prevalence of the pvl gene in S. aureus isolates using the polymerase chain reaction (PCR) technique. Methods: A total of 200 non-repeated, confirmed clinical isolates of S. aureus were used from various departments. Cefoxitin (30 ug) disc diffusion method was used as phenotypic method for detection of methicillin-resistant S. aureus (MRSA). We used PCR amplification to test for the pvl and mecA gene in S. aureus isolates. Results: Of 200 strains of S. aureus isolated in our hospital, 60 (30%) were identified as MRSA based on cefoxitin disc diffusion method. These same 30 isolates were confirmed for mecA gene by PCR. All strains had mecA gene. All mecA positive strains of S. aureus were tested for pvl gene. Of 200 S. aureus, 123 (61.5%) strains were pvl positive. Among which 33 (55%) were pvl positive MRSA and 90 (64.28%) pvl positive methicillin-susceptible S. aureus (MSSA) strains. Conclusion: The prevalence of the pvl among the MRSA isolates was found relatively higher in number among pus samples which indicate a possible key role of pvl in pathogenesis of pyogenic infections, especially skin and soft tissue infections in community setting. Keywords: Panton–Valentine leukocidin, Cefoxitin disc diffusion method, mecA, Staphylococcus aureus, Methicillin-resistant S. aureus, methicillin- susceptible S. aureus. INTRODUCTION Staphylococcus aureus is the most virulent Staphylococcus species. S. aureus can cause variety of infections, ranging from minor skin infections to post-operative wound infections. One major obstacle for the treatment of S. aureus infections is the development of antibiotic resistance in the isolates. This resistance phenomenon originated with penicillin, the first broad-spectrum antibiotic, which was discovered in the 1940s. Its adaptive power to antibiotics has resulted in the emergence of methicillin-resistant S. aureus (MRSA) in the beginning of the 1960s. Methicillin resistance is mediated by an acquired penicillin- binding protein, PBP2a, a peptidoglycan transpeptidase encoded by the mecA gene that has low affinity for beta-lactams. Thus, when the four native peptidoglycan synthetases (penicillin-binding proteins 1, 2, 3, and 4) are bound and inactivated by beta-lactams, PBP2a can still affect cell wall synthesis. mecA is harbored on the Staphylococcal chromosomal cassette mec (SCCmec), a genetic element that integrates site-specifically into the S. aureus chromosome [1]. MRSA strains are particularly serious and potentially lethal pathogens that possess virulence mechanisms including toxins, adhesions, enzymes, and immunomodulators [2]. Virulence genes play very important roles in bacterial pathogenesis [3] and S. aureus could not be an exception to this. It was in view of this that some of the virulence genes such as Panton–Valentine leukocidin (pvl), exfoliating toxin A, and toxic shock syndrome were screened for with the hope one of the virulence genes could be incriminated in S. aureus infections. Initially, MRSA infections were observed in hospitalized patients and those with chronic illnesses. These types of infections are caused by strain of S. aureus labeled as hospital-acquired MRSA (HA-MRSA). In 1990s, another type of MRSA strain was emerged that primarily causes skin and soft tissue infections in healthy people. It is called community- acquired MRSA (CA-MRSA) [4]. Molecular characterization of SCCmec types of MRSA is very essential for studying the epidemiology of MRSA. This problem is further confounded by the recent spread of CA-MRSA and the identification of vancomycin-resistant MRSA. In addition to the limited treatment options, S. aureus strains acquire and express numerous virulence determinants that continue to increase its ability to cause a wide spectrum of human disease [5,6]. pvl is a pore-forming toxin secreted by some S. aureus strains which destroy leukocytes by creating pores in the mitochondrial membrane and associated with skin and soft tissue infections. pvl is a virulence factor associated with severe MRSA infections for which routine detection is time-consuming and dependent on the culture environment [7]. © 2018 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4. 0/) DOI: http://dx.doi.org/10.22159/ajpcr.2018.v11i2.19080 Research Article