Comparative Evaluation Of Phenotypic Methods To Detect Methicillin Resistance With Mec A Gene Detection By Pcr In Staphylococcus Aureus

Authors: SONY SOMAN, SAHIRA HANEEFA, MANJUSREE SURESH

Keywords: Methicillin -Resistant Staphylococcus aureus; Cefoxitin; mecA gene; Polymerase Chain Reaction

Abstract: Background: It is crucial to employ precise, reliable, and rapid MRSA detection methods to avoid the indiscriminate use of antimicrobial drugs and make informed decisions regarding appropriate treatment and the execution of efficient measures to prevent infections. Methodology: A group of 112 MRSA isolates from different clinical specimens, initially detected using the cefoxitin disc diffusion test, underwent additional phenotypic assessments such as the Oxacillin E strip and MRSA CHROM agar. These methods were then evaluated and compared with mec A gene identification via PCR, which is regarded as the gold standard. Results: Of the 112 MRSA isolates identified by the cefoxitin disc diffusion test, 101 (90.2%) tested positive for the mec A gene. The Oxacillin E strip had a sensitivity of 98% and a specificity of 91%, while MRSA CHROM agar showed a sensitivity of 96.03% and a specificity of 82%. Among the 101 mecA-positive MRSA isolates, 44.5% met the CDC definition criteria for HA MRSA. Conclusion Our study concludes that phenotypic methods, including the cefoxitin disc diffusion test, are not completely reliable in detecting methicillin resistance in S. aureus. According to our results, combining the cefoxitin disc diffusion test with the oxacillin E strip is an effective approach for detecting MRSA in resource-constrained settings. Given the advantages of PCR, it is recommended to perform PCR for mec A gene detection on a regular basis to identify MRSA strains in important clinical specimens.