Rapid testing for methicillin-resistant Staphylococcus aureus: Implications for antimicrobial stewardship

Abstract

Assays for the rapid identification of methicillin-resistant Staphylococcus aureus (MRSA) infection are reviewed, with a discussion of their potential role in antimicrobial stewardship programs. Relative to standard culture and susceptibility testing methods, rapid MRSA assays developed during the last decade can dramatically shorten laboratory turnaround times (1-5 hours versus 48-96 hours), enabling clinicians to more quickly confirm or rule out MRSA infection and optimize antistaphylococcal therapy. Some rapid MRSA assays are based on polymerase chain reaction techniques while others use bacteriophage technology; four companies offer products approved by the Food and Drug Administration (FDA) for testing certain clinical specimens. In general, the currently available rapid MRSA tests have been demonstrated to have good sensitivity (91-100%) and specificity (95-100%), but one test product with marginally acceptable sensitivity (75%) was withdrawn from the U.S. market after reports of unacceptably high rates of false-positive and false-negative results. There is limited published evidence on the impact of any rapid MRSA assay on patient-level outcome and cost-effectiveness measures. Hospitals evaluating rapid MRSA tests should weigh factors such as their relative costs, reliability, and sample-processing times, as well as the need for policies and processes to ensure the prompt communication of test results to clinicians. Currently available rapid MRSA assays differ in specificity, sensitivity, cost, FDA-approved applications, and laboratory turnaround time, and published data on their comparative merits in terms of patient care and economic outcomes are limited. The optimal role of such tests in antimicrobial stewardship programs remains to be defined.