Switch from MRSA PCR to Agar for Nasal Screening Does Not Increase Transmission
Background: The VA has guidelines to screen inpatients on admission (A), transfer (T), and discharge (D). MRSA infection rates and transmissions have decreased dramatically nationally with a bundle for MRSA, which includes screening, improved infection prevention practices, environmental cleaning and culture change. Screening programs with PCR are expensive, but rapid. Our facility implemented a new screening program with agar (Spectra by Thermo Scientific) with a lab processing time of 24 hours.
Methods: Number of transmissions in our acute care facility (ICU and wards) were compared for 3 months prior to the intervention (period 1, October-December 2012) and 3 months after the intervention (period 2, October-December 2013) using a poisson regression model in Stata There was a wash-out period of 9 months where A & T were tested with PCR and D were tested with agar.
Results: The Incidence Rate Ratio for MRSA transmission was 1.32 (CI 0.67-2.59) for period 2 compared to period 1, t p = 0.42. MRSA admission prevalence was 14% in both periods 1 & 2. Turn-around times for agar tests were also compared to PCR tests. 4777 PCR tests were done in period 1, with a mean turn-around time of 34.9 hours (SD 27.5) compared to 4793 swab tests in period 2 with a mean turn-around time of 58.2 hours (SD 21.0). 19,074 tests were done in 2013 (at a cost for each PCR of $35.00 for reagents, $10 for labor and for each agar $2.60 for reagents and $3.40 for labor) for a potential $724812 cost savings/year (costs including labor $133518 for all agar, $ 858330 for all PCR). Infection rates stayed stable over our time periods.
Conclusion: Increases in MRSA transmissions after change to agar testing were not statistically significant. However, the rate ratio was in a positive direction and warrants continued vigilance. Turn-around time increased from 1 to 2 days (reflecting increase in test time, time to delivery of specimens and our Monday-Saturday daytime lab hours).Potential cost savings are significant. A cost-effectiveness analysis would be of interest.
K. Gupta, Paratek: Consultant, Consulting fee