Detection limits of a rapid MRSA detection assay based on multiplex real-time PCR

Abstract

I wish to report the results of a study for the limits of detection of a rapid methicillin-resistant Staphylococcus aureus (MRSA) detection assay based on a multiplex realtime polymerase chain reaction (PCR) (BD GeneOhm MRSA assay, Fukushima, Japan), which was reported in the Journal of Infection and Chemotherapy, Volume 15 (No. 4), 2009 [1]. ATCC 33591 (MRSA) was recovered on Mueller Hinton agar by overnight incubation at 37 C. Colonies were picked from the agar, adjusted to Mcfarland 0.5, and diluted to 10–10 colony-forming units (CFU)/ml (corresponding to approximately 10–10 CFU/reaction) by the sample buffer (Tris-EDTA buffer) of the BD GeneOhm MRSA assay kit [1]. The BD GeneOhm MRSA assay was performed four times at about the same concentration to determine the limits of detection. Table 1 shows the result of the tests. All tests were positive with 10–10 and 10 CFU/reaction; however, only half of the tests were positive with at a reaction concentration of 10 CFU. Although the results of the study show that at least 10 CFU/reaction is necessary to detect MRSA stably by the BD GeneOhm MRSA assay, compilation of data and further study with clinical samples are needed. Reference