PCR as a tool for direct detection of methicillin resistance in clinical pus specimens

Introduction: Methicillin Resistant Staphylococcus aureus (MRSA) is a multidrug-resistant pathogen responsible for mild to serious infections. Conventional culture-based methods for MRSA detection are reliable but time-consuming. Early, accurate direct sample-based MRSA detection in clinical samples can positively influence disease prognosis by aiding effective antibiotic therapy, thereby reducing patient mortality and hospital-acquired infections.Objective: To evaluate the utility of direct polymerase chain reaction (PCR) detection of the mecA gene for rapid identification of MRSA in clinical pus specimens.Materials and Methods: A prospective study was conducted over one year at a tertiary care center in Southern India. Clinical pus samples yielding the growth of Staphylococcus aureus were tested for methicillin resistance using cefoxitin disk and by VITEK-2 system. Culture confirmed MRSA were further subjected to direct PCR for detection of the mecA gene from the clinical specimen.Results: A total of 46 clinical pus samples yielding the growth of MRSA on culture were included in the study. All 46 pus samples (100%) were positive for mecA gene by direct clinical sample PCR. The turnaround time (TAT) reduced by 60 hours (~2.75 days), compared to conventional culture- based methods.Conclusion: Disc diffusion is no doubt simple and economical method for detection of methicillin resistance. PCR based mec A gene detection is equally efficient method for rapid MRSA detection. If resource constraints are overcome this method can provide a time bound advantage of swift accurate diagnosis. Thus, empowering the clinician towards speedy initiation of targeted antibiotic therapy and potentially reducing MRSA- associated morbidity and nosocomial transmission.