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571 Impact of rapid detection of methicillin resistant Staphylococcus aureus (MRSA) by real-time polymerase chain reaction (RT-PCR) on initiation of isolation precautions

Sunday, April 3, 2011
Trinity Ballroom (Hilton Anatole)
Jo-anne M. Salangsang, MD, MS , University of Pittsburgh Medical Center, Pittsburgh, PA
Traci L. McGaha, RN , University of Pittsburgh Medical Center, Pittsburgh, PA
Diana L. Pakstis, RN , University of Pittsburgh Medical Center, Pittsburgh, PA
Kathleen A. Shutt, MS , University of Pittsburgh, Pittsburgh, PA
Jamie L. Gray, BS , University of Pittsburgh Medical Center, Pittsburgh, PA
Maria M. Brooks, PhD , University of Pittsburgh, Pittsburgh, PA
Jane W. Marsh, PhD , University of Pittsburgh Medical Center, Pittsburgh, PA
A. William Pasculle, ScD , University of Pittsburgh Medical Center, Pittsburgh, PA
Lee H. Harrison, MD , University of Pittsburgh, Pittsburgh, PA
Carlene A. Muto, MD, MS , University of Pittsburgh Medical Center, Pittsburgh, PA

Background:   Active surveillance testing for MRSA using nasal swab culture on chromogenic media and institution of isolation and contact precautions for MRSA colonized patients was being performed at our tertiary care facility, but the impact of utilizing rapid screening methods was unknown.

Objective: (1) To evaluate the impact of rapid detection of MRSA by RT-PCR on time to initiation of appropriate isolation precautions in patients newly identified as MRSA colonized, (2) assess the impact of an automated push MRSA isolation order (PIO), and (3) generate data for modeling the morbidity and economic benefits of earlier detection of MRSA colonization.

Methods: Subjects were hospitalized patients undergoing nasal screening for MRSA and not previously in isolation precautions for MRSA or other drug-resistant organisms.  Phase 1 (pre-PCR and pre-PIO) was baseline practice: standard microbiology techniques for identifying MRSA (CHROMagar) and automated electronic MRSA alerts received by infection control and the point of care to communicate the new isolation requirement. Phase 2 (pre-PCR and with PIO) involved addition of a real-time push isolation order in the electronic health record to initiate isolation precautions for newly identified MRSA colonized patients. Phase 3 (with PCR and PIO) involved application of the BD GeneOhm MRSA ACP RT-PCR assay for MRSA detection instead of culture. Mean time from nasal swab collection to test result and MRSA alert/isolation initiation for subjects with newly identified MRSA was measured in 3 phases and compared using t-test. Observation of the presence of isolation signs, gowns, gloves, and dedicated stethoscopes in patient rooms was conducted and the proportion of patients observed to have all the components at 1 hour from MRSA alert was compared using Pearson chi-square test.

Results:   There were 17, 18, and 30 subjects in Phases 1, 2, and 3 respectively. Mean time from swab collection to test result and to MRSA alert/initiation of isolation were significantly decreased from 42 +/- 12 hours in Phases 1 and 2 (pre-PCR) to 17 +/- 7 hours in Phase 3 (with PCR), p < .001.The proportion of patients observed to have all the equipment for isolation precautions at 1 hour from alert significantly increased from 5 of 17 (29.4%) in Phase 1 (pre-PIO) to 28 of 48 (58.3%) in Phases 1 and 2 (with PIO), p = .04.

Conclusions: RT-PCR significantly decreased the time from nasal swab collection to initiation of isolation compared to routine culture. Real-time automated push MRSA isolation order significantly impacted the proportion of patients isolated within 1 hour of MRSA alert compared to MRSA point of care alerts alone. The cost-effectiveness and morbidity impact of RT-PCR/ automated orders remains to be determined.