Reliability of the BD GeneOhm Methicillin-Resistant <i>Staphylococcus aureus</i> (MRSA) Assay in Detecting MRSA Isolates with a Variety of Genotypes from the United States and Taiwan

<jats:title>ABSTRACT</jats:title> <jats:p> The BD GeneOhm methicillin-resistant <jats:italic>Staphylococcus aureus</jats:italic> (MRSA) assay is a molecular screening test for detection of MRSA in nasal colonization. This assay coamplifies the extremity of staphylococcal chromosome cassette <jats:italic>mec</jats:italic> (SCC <jats:italic>mec</jats:italic> ) and adjacent chromosomal DNA at the SCC <jats:italic>mec</jats:italic> insertion site. Increasing reports of novel SCC <jats:italic>mec</jats:italic> types and the diverse genetic backgrounds of MRSA strains prompted us to test the accuracy of the BD GeneOhm MRSA kit with 914 MRSA isolates with a variety of SCC <jats:italic>mec</jats:italic> types harbored in 21 genetic backgrounds, as determined by the multilocus sequence type (ST). The BD GeneOhm MRSA assay was performed on colony lysates; purified genomic DNA (0.2 pg/μl and 0.2 ng/μl) was tested to confirm negative results from lysates. Of 914 MRSA isolates tested, 911 tested positive (detection rate, 99.7%). The SCC <jats:italic>mec</jats:italic> types carried by assay-positive isolates were I, II, III, IV, V, V <jats:sub>(5C2&5)</jats:sub> , VI, and VIII and SCC <jats:italic>mec</jats:italic> composite islands with <jats:italic>mec</jats:italic> class A and <jats:italic>ccr</jats:italic> complexes 2 and 4. One of the assay-negative isolates had a community-associated genotype: ST8, SCC <jats:italic>mec</jats:italic> type IV. However, this was an outlier among the 99.8% (434/435) ST8, SCC <jats:italic>mec</jats:italic> type IV-containing isolates that tested positive. The two other assay-negative isolates had a health care-associated genotype (ST5); both carried a distinct, uncommon, composite SCC <jats:italic>mec</jats:italic> type. In summary, the BD GeneOhm MRSA assay had a high rate of detection of MRSA isolates harboring common and uncommon SCC <jats:italic>mec</jats:italic> types from the United States and Taiwan. </jats:p>