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

Abstract

The BD GeneOhm methicillin-resistant Staphylococcus aureus (MRSA) assay is a molecular screening test for detection of MRSA in nasal colonization. This assay coamplifies the extremity of staphylococcal chromosome cassette mec (SCCmec) and adjacent chromosomal DNA at the SCCmec insertion site. Increasing reports of novel SCCmec 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 SCCmec 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/l and 0.2 ng/l) was tested to confirm negative results from lysates. Of 914 MRSA isolates tested, 911 tested positive (detection rate, 99.7%). The SCCmec types carried by assay-positive isolates were I, II, III, IV, V, V (5C2&5) , VI, and VIII and SCCmec composite islands with mec class A and ccr complexes 2 and 4. One of the assay-negative isolates had a communityassociated genotype: ST8, SCCmec type IV. However, this was an outlier among the 99.8% (434/435) ST8, SCCmec 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 SCCmec type. In summary, the BD GeneOhm MRSA assay had a high rate of detection of MRSA isolates harboring common and uncommon SCCmec types from the United States and Taiwan.

Methicillin-resistant Staphylococcus aureus from Northwest marine and freshwater recreational beaches

“…Three isolates with ST1959 were taken from beach A and have been previously found in squirrels from the UK, and all three beaches have indigenous squirrel populations. The remaining isolates have been previously found in humans (ST109), humans and animals (ST15, ST45, ST88, ST97), or humans and meat products (ST5, ST6, ST8, ST30) (Armand‐Lefevre et al ., ; Collery et al ., ; Boyl‐Vavra & Daum, ; Cuny et al ., ; Deleo et al ., ; Graveland et al ., ; Hata et al ., ; Kawaguchiya et al ., ; Lin et al ., ; Waters et al ., ).…”

Bead beating-based continuous flow cell lysis in a microfluidic device

“…On the other hand, deoxyribonucleic acid (DNA) detection kits have appeared as commercial alternatives. [4][5][6] Nevertheless, these comprise many sample manipulation steps and need a qualied worker, deriving in potential cross contamination risks. The solution to overcome these limitations arises in integrating different analysis steps (i.e.…”

Rapid testing for methicillin-resistant Staphylococcus aureus: Implications for antimicrobial stewardship

“…14 Like the hyplex StaphyloResist, the GeneOhm assay targets the mecA gene, but it also targets the orfX primer specific to S. aureus, which ensures that the assay will not mistake methicillin-resistant, coagulasenegative Staphylococcus species for MRSA, although false-positives have been reported. 15,16 Test results are available in as little as two hours, and the test is approved by FDA for surveillance of MRSA in the nares as well as the groin and wound specimens, with good sensitivity and specificity. 12,[17][18][19][20][21] However, given that the assay is only approved for surveillance and there is a lack of evidence supporting its use in making real-time antimicrobial decisions, the GeneOhm MRSA ACP Assay likely has little value in antimicrobial stewardship activities.…”