Evaluation of the IDI-MRSA Assay for Detection of Methicillin-Resistant Staphylococcus aureus from Nasal and Rectal Specimens Pooled in a Selective Broth

Comparative evaluation of a rapid MRSA detection assay based on multiplex real-time PCR versus MRSA screening cultures containing egg yolk

“…13 But our results indicate that using the egg yolk reaction instead of the coagulase test is inappropriate, and the coagulase test is indispensable as a standard method for the discrimination of S. aureus from coagulase-negative staphylococci. In the BD GeneOhm MRSA assay, one MSSA strain (8.0% of MSSA) was positive, and similar studies by some researchers have found false-positive MSSA (4.0% of MSSA) in the IDI-MRSA assay (former name of the BD GeneOhm MRSA assay) with isolates from nasal and rectal swabs (Desjardins et al 9 and false-positive MSSA (4.6% of MSSA) with multiplex real-time PCR with MSSA isolates (Huletsky et al). 10 A possible reason for the false-positive MSSA in the BD GeneOhm MRSAassay is that SCCmec-orfX was detected even though the mecA gene had been lost from SCC mec elements because of the difference of the regions between mecA and SCCmec-orfX.…”

“…[8][9][10] Pourmedia MRSA II is an MRSA screening culture containing egg yolk, mannitol, and cefoxitin (CFX) developed by Eiken Chemical. We obtained 50 MRSA strains, 16 methicillin-resistant S. epidermidis (MRSE) strains, 12 methicillin-sensitive S. aureus (MSSA) strains, and 10 methicillin-sensitive S. epidermidis (MSSE) strains from the blood of patients admitted to Keio University Hospital between 2004 and 2006.…”

Microbial monitoring of the hospital environment: why and how?

“…74 Culture methods have detected nosocomial pathogens such as MRSA on surfaces where PCR has failed, and false-positive PCR results can occur due to the presence of meticillin-susceptible S. aureus in clinical samples. 74,75 As the number of bacteria on hospital surfaces is usually less than that in clinical specimens, there is a need for the development and evaluation of molecular methods to detect small numbers of bacteria and mixed microbial populations. 76 Changes and variation in the genetic make-up of nosocomial bacterial pathogens can also limit the use of PCR-based methods for the detection of multi-resistant pathogens.…”

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

“…False-positive diagnoses are possibly caused in the BD geneOhm MRSA TM assay by some MSSA lineages that carry SCCmec without possessing the functional region containing mecA [12]. In fact, approximately 5% of bacterial isolates identified as MRSA by the BD geneOhm MRSA TM assay are phenotypically defined as MSSA [8,13,14]. False-negative diagnoses can be attributed to a bacterial count below the limit of detection or the existence of DNase or PCR inhibitors in the sample.…”