Evaluation of the BD GeneOhm Assay Using the Rotor-Gene 6000 Platform for Rapid Detection of Methicillin-Resistant Staphylococcus aureus from Pooled Screening Swabs

Abstract

As health services move toward universal methicillin-resistant Staphylococcus aureus (MRSA) screening for hospital admissions, the most cost-effective approach is yet to be defined. In this study, one of the largest to date, we evaluated the performance of the BD GeneOhm MRSA assay on the Rotor-Gene 6000 thermal cycler, using samples taken directly from pooled MRSA screens. Results were compared with the same assay performed on the Smart-Cycler II platform and overnight broth culture. Samples yielding discrepant results were subjected to detailed analysis with an in-house PCR and patient note review. A total of 1,428 pooled MRSA screens were tested. Sensitivities and specificities of 85.3% and 95.8% for the Rotor-Gene and 81% and 95.7% for the Smart-Cycler were obtained, compared with broth enrichment. The sensitivity of the BD GeneOhm assay was increased to 100% when the results of in-house PCR and patient note review were taken into account. This study demonstrates that the Rotor-Gene 6000 thermal cycler is a reliable platform for use with the BD GeneOhm assay. It also proves that commercial PCR can be performed direct on pooled samples in selective broth, without the need for overnight incubation.

Comparison of the BD Max Methicillin-Resistant Staphylococcus aureus (MRSA) Assay and the BD GeneOhm MRSA Achromopeptidase Assay with Direct- and Enriched-Culture Techniques Using Clinical Specimens for Detection of MRSA

“…Positive predictive value (PPV) was 83.8% for the BD Max MRSA assay and 69.8% for the BD GeneOhm MRSA ACP assay (P ϭ 0.19, two-sided Fisher's exact test). The PPV for the BD GeneOhm MRSA ACP assay is within the range that has been observed before (3,8,(17)(18)(19)(20)(21); the slightly higher PPV for the new BD Max MRSA assay might help to avoid unnecessary infection control measures, especially in low-prevalence settings. Negative predictive values (NPVs) were high for both assays (99.7%).…”

“…The observed differences in sensitivity and specificity between the two molecular assays were not statistically significant. The test characteristics of the BD Max MRSA assay are in the range of what has been observed before for the BD GeneOhm MRSA assay (3,8,11,20) and the ACP assay (17)(18)(19). Comparison of the two molecular assays gave a Cohen's kappa of 0.816, indicating good agreement.…”

“…It combines cell lysis, nucleic acid extraction, PCR setup, amplification, and detection in a single machine, thereby facilitating use of molecular tests. The aim of this study was to evaluate the BD Max MRSA assay, compared with the widely used BD GeneOhm MRSA achromopeptidase (ACP) assay (5,11,17,18,20), using direct and enriched culture as the reference method for detection of MRSA.…”

“…It combines cell lysis, nucleic acid extraction, PCR setup, amplification, and detection in a single machine, thereby facilitating use of molecular tests. The aim of this study was to evaluate the BD Max MRSA assay, compared with the widely used BD GeneOhm MRSA achromopeptidase (ACP) assay (5,11,17,18,20), using direct and enriched culture as the reference method for detection of MRSA.The study was conducted at the 2,000-bed tertiary care University Hospital Heidelberg from October 2011 to January 2012. Screening swabs (BBL CultureSwab, liquid Stuart; BD) collected from patients admitted to intermediate and intensive care units, from patients admitted from external hospitals, and from surgical patients with wound infections were used.…”

Adjunctive mecA PCR for Routine Detection of Methicillin Susceptibility in Clinical Isolates of Coagulase-Negative Staphylococci

“…Two in-house-developed assays were used in this study: (i) a first-line multiplex assay targeting novel sequences in the mecA and sa442 genes (the mecA1 assay) and (ii) a confirmatory mecA monoplex, targeting a different region in the mecA gene (the mecA2 assay). The multiplex assay was based on methods described previously but used a newly designed reverse primer for the mecA gene, MecR2 (5=-ATC AGT ATT TCA CCT TGT CCG-3=) (16,17). The mecA and sa442 PCR amplification mixture was as previously described (17), using 10 l of extracted DNA sample in a total volume of 30 l, with the following modifications.…”