title: Evaluation and use of a rapid Staphylococcus aureus assay by an antimicrobial stewardship program.
abstract: OBJECTIVE
  The performance of a rapid test for methicillin-resistant Staphylococcus aureus (MRSA) in a large community hospital was investigated.
  
  
  METHODS
  A prospective observational study was conducted to evaluate an immunochromatographic assay (Alere PBP2a Culture Colony Test, Alere Scarborough, Inc.) for rapid differentiation of MRSA and methicillin-susceptible S. aureus (MSSA) strains using isolates cultured overnight on common laboratory media. S. aureus isolates cultured for 12-24 hours were tested with the assay, which detects penicillin-binding protein 2a (PBP2a) and provides results in six minutes. The test results were compared with data from standard overnight antimicrobial susceptibility testing to determine the assay's sensitivity and specificity. Changes in therapy associated with use of the rapid assay were evaluated.
  
  
  RESULTS
  Over an 11-month period, 661 inpatient isolates from mostly nonhematologic sites were tested. There were six false-negative results, indicating assay sensitivity of 98.4%, with no false positives (specificity of 100%). Eight invalid test results were documented. During designated evaluation periods, a total of 169 patient cases involving PBP2a testing were reviewed by the hospital's antimicrobial stewardship pharmacist. In 63 of those cases (37%), changes in therapy were implemented on the day of test result posting. Interventions often involved switching patients from inappropriate to appropriate MRSA therapy or optimizing MRSA- or MSSA-targeted therapy.
  
  
  CONCLUSIONS
  An assay for quickly differentiating between MRSA and MSSA was highly sensitive, highly specific, and inexpensive in actual hospital use and led to rapid prescription of appropriate antistaphylococcal therapy 24-48 hours after culture specimens were collected.
authors.affiliation: Tamara L. Trienski, Pharm.D., is Clinical Lead Pharmacist-Antimicrobial Stewardship; Heather L. Barrett, M.D., is Postgraduate Year IV Pathology Resident; Timothy R. Pasquale, Pharm.D., M.B.A., is Clinical Lead Pharmacist-Infectious Disease; and Joseph R. DiPersio, Ph.D., DABMM, is Director of Microbiology, Summa Health System/Akron City Hospital, Akron, OH. Thomas M. File Jr, M.D., M.Sc., MACP, FIDSA, FCCP, is Chair, Division of Infectious Disease, Summa Health System/Akron City Hospital, and Professor, Internal Medicine, and Master Teacher and Chair, Infectious Disease Section, Northeast Ohio Medical University, Rootstown.
authors.forename: Tamara L
authors.initials: TL
authors.lastname: Trienski
authors.forename: Heather L
authors.initials: HL
authors.lastname: Barrett
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Pasquale
authors.forename: Joseph R
authors.initials: JR
authors.lastname: DiPersio
authors.forename: Thomas M
authors.initials: TM
authors.lastname: File
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001431:Bacteriological Techniques; D002846:Chromatography, Affinity; D005188:False Negative Reactions; D006764:Hospitals, Community; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000302:isolation & purification*; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents