title: Rapid screening of methicillin-resistant Staphylococcus aureus using PCR and chromogenic agar: a prospective study to evaluate costs and effects.
abstract: Pre-emptive isolation of suspected methicillin-resistant Staphylococcus aureus (MRSA) carriers is considered essential for controlling the spread of MRSA, but noncolonized patients will be isolated unnecessarily as a result of a delay in diagnosis of 3-5 days with conventional cultures. We determined costs per isolation day avoided, and incremental costs of rapid MRSA screening tests when added to conventional screening, but with decisions on isolation measures based on PCR results. A prospective multicentre study evaluating BD GeneOhm MRSA PCR (`IDI') (BD Diagnostics, San Diego, CA, USA), Xpert MRSA (`GeneXpert') (Cepheid, Sunnyvale, CA, USA) and chromogenic agar (MRSA-ID) (bioMérieux, Marcy-l'Etoile, France) was performed in 14 Dutch hospitals. Among 1764 patients at risk, MRSA prevalence was 3.3% (n=59). Duration of isolation was 19.7 and 16.1 h with IDI and GeneXpert, respectively, and would have been 30.0 and 76.2 h when based on chromogenic agar and conventional cultures, respectively. Negative predictive values (at a patient level) were 99.5%, 99.1% and 99.5% for IDI, GeneXpert and chromogenic agar, respectively. Numbers of isolation days were reduced by 60% and 47% with PCR-based and chromogenic agar-based screening, respectively. The cost per test was €56.22 for IDI, €69.62 for GeneXpert and €2.08 for chromogenic agar, and additional costs per extra isolation day were €26.34. Costs per isolation day avoided were €95.77 (IDI) and €125.43 (GeneXpert). PCR-based decision-making added €153.64 (IDI) and €193.84 (GeneXpert) per patient to overall costs and chromogenic testing would have saved €30.79 per patient. Rapid diagnostic testing safely reduces the number of unnecessary isolation days, but only chromogenic screening, and not PCR-based screening, can be considered as cost saving.
authors.affiliation: Department of Medical Microbiology  Department of Internal Medicine and Infectious Diseases, University Medical Center, Utrecht, the Netherlands.
authors.forename: M W M
authors.initials: MW
authors.lastname: Wassenberg
authors.forename: J A J W
authors.initials: JA
authors.lastname: Kluytmans
authors.forename: A T A
authors.initials: AT
authors.lastname: Box
authors.forename: R W
authors.initials: RW
authors.lastname: Bosboom
authors.forename: A G M
authors.initials: AG
authors.lastname: Buiting
authors.forename: E P M
authors.initials: EP
authors.lastname: van Elzakker
authors.forename: W J G
authors.initials: WJ
authors.lastname: Melchers
authors.forename: M M L
authors.initials: MM
authors.lastname: van Rijen
authors.forename: S F T
authors.initials: SF
authors.lastname: Thijsen
authors.forename: A
authors.initials: A
authors.lastname: Troelstra
authors.forename: C M J E
authors.initials: CM
authors.lastname: Vandenbroucke-Grauls
authors.forename: C E
authors.initials: CE
authors.lastname: Visser
authors.forename: A
authors.initials: A
authors.lastname: Voss
authors.forename: P F G
authors.initials: PF
authors.lastname: Wolffs
authors.forename: M W H
authors.initials: MW
authors.lastname: Wulf
authors.forename: A A
authors.initials: AA
authors.lastname: van Zwet
authors.forename: G A
authors.initials: GA
authors.lastname: de Wit
authors.forename: M J M
authors.initials: MJ
authors.lastname: Bonten
mesh_terms: D000362:Agar; D002353:Carrier State / Q000175:diagnosis* / Q000191:economics / Q000382:microbiology; D002863:Chromogenic Compounds; D003362:Cost-Benefit Analysis; D003428:Cross Infection; D003955:Diagnostic Tests, Routine; D017048:Health Care Costs; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D010356:Patient Isolation / Q000191:economics*; D016133:Polymerase Chain Reaction / Q000191:economics* / Q000379:methods; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000191:economics / Q000382:microbiology
chemical_list: D002863:Chromogenic Compounds; D000362:Agar