title: Evaluation of multiple real-time PCR tests on nasal samples in a large MRSA surveillance program.
abstract: OBJECTIVE
  We evaluated the LightCycler MRSA Advanced Test (Roche Molecular Diagnostics, Pleasanton, CA), the BD MAX MRSA assay (Becton Dickinson, Franklin Lakes, NJ), and the Xpert MRSA assay (Cepheid, Sunnyvale, CA) on nasal samples using the same population.
  
  
  METHODS
  Admission and discharge nasal swabs were collected from inpatients using a double-headed swab. One swab was plated onto CHROMagar MRSA (CMA; Becton Dickinson, Sparks, MD) and then broken off into tryptic soy broth (TSB) for enrichment. TSB was incubated for 24 hours and then plated to CMA. The molecular tests were performed on the second swab. We analyzed the cost benefit of testing to evaluate what parameters affect hospital resources.
  
  
  RESULTS
  A total of 27,647 specimens were enrolled. The sensitivity/specificity was 98.3%/98.9% for the LightCycler MRSA Advanced Test and 95.7%/98.8% for the Xpert MRSA assay, but the difference was not significant. The positive predictive value was 86.7% for the LightCycler MRSA Advanced Test, 82.7% for the Xpert MRSA assay (P > .1), and 72.2% and for the BD MAX MRSA test (P < .001 compared with the LightCycler MRSA Advanced Test). All three assays were cost-effective, with the LightCycler MRSA Advanced Test having the highest economic return.
  
  
  CONCLUSIONS
  Our results suggest that the performance of the three commercial assays is similar. When assessing economic cost benefit of methicillin-resistant Staphylococcus aureus screening, the two measures with the most impact are the cost of the test and the specificity of the assay results.
authors: From the NorthShore University HealthSystem, Evanston, IL, and.
authors: Parul A
authors: PA
authors: Patel
authors: From the NorthShore University HealthSystem, Evanston, IL, and the NorthShore University of Chicago Pritzker School of Medicine, Chicago, IL.
authors: Ari
authors: A
authors: Robicsek
authors: From the NorthShore University HealthSystem, Evanston, IL, and.
authors: Althea
authors: A
authors: Grayes
authors: From the NorthShore University HealthSystem, Evanston, IL, and.
authors: Donna M
authors: DM
authors: Schora
authors: From the NorthShore University HealthSystem, Evanston, IL, and.
authors: Kari E
authors: KE
authors: Peterson
authors: From the NorthShore University HealthSystem, Evanston, IL, and.
authors: Marc O
authors: MO
authors: Wright
authors: From the NorthShore University HealthSystem, Evanston, IL, and the NorthShore University of Chicago Pritzker School of Medicine, Chicago, IL. lance1@uchicago.edu.
authors: Lance R
authors: LR
authors: Peterson
mesh_terms: D000465:Algorithms; D004269:DNA, Bacterial / Q000235:genetics; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*; D009296:Nasal Cavity / Q000382:microbiology*; D011237:Predictive Value of Tests; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology
chemical_list: D004269:DNA, Bacterial
keywords: MRSA surveillance; Real-time PCR; Staphylococcus aureus