Significantly Improved Performance of a Multitarget Assay Over a Commercial SCCmec-Based Assay for Methicillin-Resistant Staphylococcus aureus Screening Applicability for Clinical Laboratories

Detection of the SCCmec gene is a common strategy for methicillin-resistant Staphylococcus aureus (MRSA) screening assays. However, if SCCmec is used alone, it may not be specific for detecting MRSA. Herein, we describe an in-house MSRA PCR-based screening assay involving detection of three targets (nuc, coa, and mecA). The assay is suitable for a wide range of real-time PCR platforms used in clinical microbiological laboratories. Performance characteristics of the in-house assay were significantly improved compared with the commercial assay, leading to an increase of positive predictive value by 40%. Compared with the bacterial culture, the sensitivity, specificity, and positive and negative predictive values of the in-house PCR assay were 100% (95% CI >83.2%), 99.2% (95% CI = 98.2% to 99.8%), 80% (95% CI = 59.3% to 93.2%), and 100% (95% CI >99.2%), respectively.