Comparison of Phenotypic and Molecular Methods for Rapid and Accurate Detection of Methicillin-resistant Staphylococcus aureus from Clinical Specimens: A Cross-sectional Observational Study from a Tertiary Care Center in New Delhi

Background and Aim: Accurate and rapid identification of methicillin-resistant Staphylococcus aureus (MRSA) in clinical specimens is essential for timely decisions on patient isolation procedures and effective antimicrobial therapy. Hence, this study was carried out to evaluate the usefulness of methods such as MRSA latex agglutination and MRSA CHROMagar for rapid and accurate detection of MRSA. Materials and Methods: A total of 86 isolates of S. aureus identified using the VITEK-2 Compact system were included in this study. These isolates were further tested by MRSA CHROMagar and MRSA latex agglutination test for their MRSA status. Results of these phenotypic tests were compared against the gold standard molecular method, i.e., mec A fem B multiplex polymerase chain reaction. Results: MRSA CHROMagar was found to have 100% sensitivity and 100% specificity. The MRSA latex agglutination test had 100% sensitivity and 78.26% specificity; positive predictive value (PPV) was 92.65%, and the negative predictive value (NPV) was 100%. However, as compared to MRSA CHROMagar, which took 18–24 h, MRSA latex agglutination took only 10–15 min for the result. Conclusion: MRSA latex agglutination test was found to have very high sensitivity, specificity, PPV, and NPV and has a very short turnaround time for MRSA detection, and thereby very helpful in taking therapeutic decisions as well as infection prevention measures.