Effectiveness of methicillin-resistant Staphylococcus aureus surveillance among exposed roommates in community hospitals: Conventional culture versus direct PCR.

Roommates of unrecognized nosocomial methicillin-resistant Staphylococcus aureus (MRSA) cases are at a higher acquisition risk; however, optimal surveillance strategies are unknown. Using simulation, we analyzed surveillance testing and isolation strategies for MRSA among exposed hospital roommates. We compared isolating exposed roommates until conventional culture testing on day 6 and a nasal polymerase chain reaction test on day 3 (PCR3) with/without day 0 culture testing (Cult0). The model represents MRSA transmission in medium-sized hospitals using data and recommends best practices from the literature and Ontario community hospitals. Cult0 + PCR3 incurred a slightly lower number of MRSA colonizations and 38.9% lower annual cost in the base case compared to Cult0 + culture testing on day 6 because the reduced isolation cost compensated for the increased testing cost. The reduction in MRSA colonizations was due to a 54.5% drop in MRSA transmissions during isolation as PCR3 reduced the exposure of MRSA-free roommates to new MRSA carriers. Removing the day 0 culture test from Cult0 + PCR3 increased total cost, the number of MRSA colonization, and missed cases by $1,631, 4.3%, and 50.9%, respectively. Improvements were higher under aggressive MRSA transmission scenarios. Adopting direct nasal polymerase chain reaction testing for determining post-exposure MRSA status reduces transmission risk and costs. Day 0 culture would still be beneficial. • Exposed roommates of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) cases are at high acquisition risk. • We analyzed MRSA surveillance and isolation strategies among exposed roommates. • We developed a computer simulation model to mimic transmission and progression. • Using nasal polymerase chain reaction testing for MRSA surveillance reduces transmission risk and costs. • Day 0 culture test on top of day 3 polymerase chain reaction test is beneficial for MRSA surveillance. [ABSTRACT FROM AUTHOR]