Comparison of Latex Agglutination Test with Polymerase Chain Reaction for Detection of mecA Gene in Methicillin Resistant Staphylococcus aureus

Background: Antimicrobial resistance is a devastating question that threatens health globally. The extensive, indiscriminate and unnecessary consumption of antibiotics for humans, as well as wildlife and in agriculture; lead to the development of notoriously resistant Staphylococcus aureus; through possession of mecA gene, encoded by modified Penicillin binding protein (PBP2a); being labeled "Methicillin resistant Staphylococcus aureus". Conventional phenotypic techniques for MRSA detection rely on standardization of cultural characteristics. The latex agglutination method can be adopted as an accurate strategy for rapid detection of MRSA. Methodology: A total of 713 consecutive, non-duplicate isolates of Staphylococcus aureus were processed. Methicillin resistance was determined using cefoxitin (30 mu g) by Kirby-Bauer method following Clinical and Laboratory Standards Institute (CLSI) guideline, latex agglutination method; and PCR for mecA gene. Results: The results showed that out of 713 Staphylococcus aureus isolates, 12.90% isolates were detected as MRSA due to resistance to cefoxitin. By latex agglutination method, 87 (94.50%) were positive for PBP2a; while on PCR mecA gene was detected only in 82 (89.10%) MRSA isolates. When assessed with PCR (gold standard) the sensitivity and diagnostic accuracy of latex agglutination was 100% and 94.57%, respectively. Conclusion: Latex agglutination test can be used as a prompt and reliable diagnostic technique for mecA gene detection in MRSA isolates, where molecular methods are limited. This can effectively minimize the misdiagnosis of resistant strains, and over/misuse of antibiotics.