MRSA detection: comparison of two molecular methods (BD GeneOhm PCR assay and Easy-Plex) with two selective MRSA agars (MRSA-ID and Oxoid MRSA) for nasal swabs.
Screening of patients is an important component for methicillin-resistant Staphylococcus aureus (MRSA) containment. The aim of this study was to determine the utility of molecular methods compared to selective agars for MRSA detection. Consecutive high risk patients (n = 200) were screened for nasal MRSA colonization using chromogenic selective agars (MRSA ID and CMRSA) as well as the BD GeneOhm MRSA (previously known as IDI-MRSA) and the Easy-Plex commercial real time PCR assays. The sensitivities of the molecular methods were similar to the BD GeneOhm MRSA (86%) and Easy-Plex (84%). The chromogenic agars, MRSA ID and CMRSA, showed sensitivities of 62% and 84%, respectively. Sensitivity was influenced by both the MRSA antibiograms and MRSA clonal type. The specificity was >98% in all methods except for the Easy-Plex assay (90%). Sensitivity of selective agars increased with 48 hours of incubation with a corresponding decrease in specificity. In conclusion, molecular detection methods for MRSA remain sensitive and rapid but are associated with greater expense.
van Hal
S J
SJ
Department of Microbiology and Infectious Diseases, StVincent's Hospital, Darlinghurst, NSW, Australia. vanhal@gotalk.net.au
Jennings
Z
Z
Stark
D
D
Marriott
D
D
Harkness
J
J
D000362:Agar; D001431:Bacteriological Techniques / Q000379:methods*; D003470:Culture Media / Q000737:chemistry; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D009296:Nasal Cavity / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity
D003470:Culture Media; D000362:Agar