Multiplex System: Identification of Vancomycin (Vana) And Methicillin (Meca) Resistance Genes In Staphylococcus Aureus

Introduction: Emergence of Methicillin resistant Staphylococcus aureus (MRSA) and Vancomycin resistant Staphylococcus aureus (VRSA) strain from different regions of the world poses a grave concern to human health. Antibiotic resistance in S. aureus is mainly because of the genetic factors which modify or disrupt their target site on bacteria. Methods: This study is focused to identify the vancomycin and methicillin resistance gene in antibiotic sensitive and resistant S. aureus. The pure cultures of S. aureus were isolated, subjected to morphological and biochemical characterization. Antibiotic susceptibility testing was done to check the resistance pattern. DNA isolation was followed by genotyping of the antibiotic resistance genes (VanA and MecA) and housekeeping gene (AroE) was done through multiplex PCR method. All the strains showed the colonial, microscopic and biochemical characteristics (catalase and coagulase positive) specific for S. aureus. Results: Majority of the strains were resistant to cefixime (80 %) and least resistance was observed with fusidic acid (0%), while resistance frequency of the remaining antibiotics falls between them. All the strains showed the presence of housekeeping AroE gene with frequency of VanA is 2% and MecA is 24% which coincides with the findings of antibiotic resistance testing. For VanA, there might be other resistance genes of vancomycin cassette which confer the resistance against it. Conclusion: The study will help to discriminate the vancomycin and methicilin sensitive and resistance strains of S. aureus based on their respective genetic factors and help to validate the underlying mechanism in the acquisition of antibiotic resistance.