The performance of the BD geneOhm MRSA™ assay for MRSA isolated from clinical patients in Japan, including the effects of specimen contamination and ways to improve it

The BD geneOhm MRSA™ assay has been increasingly used in recent years, and it is possible to use it to screen and detect methicillin-resistant Staphylococcus aureus (MRSA) from a specimen within 2 h. The purpose of the present study was to evaluate the performance, i.e., the specificity and sensitivity, of the BD geneOhm MRSA™ assay to detect MRSA. Its specificity was assessed to be 100% compared to bacterial culture methods, which are commonly used in medical laboratories. Its bacterial limit of detection was over 10 colony-forming units (cfu) per reaction, although MRSA was detected at a cfu below 10 per reaction in a few samples. Additionally, the effect of MRSA isolate contamination was examined. While contamination with protein or other bacteria did not affect the outcome, contamination with a high concentration of blood resulted in an unresolved outcome. To inactivate polymerase chain reaction (PCR) inhibitors, the DNA samples were freeze–thawed prior to the BD geneOhm MRSA™ assay, which led to the sensitivity of the assay increasing. In summary, the BD geneOhm MRSA™ assay is rapid and shows high specificity and sensitivity of cultured MRSA isolates. It will, therefore, be a valuable diagnostic tool for detecting MRSA in specimens from clinical patients.