Screening the at risk of MRSA

Link: Methicillin-Resistant Staphylococcus aureus Infection or Colonization at Hospital Admission: Multivariable Risk Factor Screening to Increase Efficiency of Surveillance Culturing — Haley et al., 10.1128/JCM.00315-07 — Journal of Clinical Microbiology.

Identifying methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection present at admission has become important in reducing subsequent nosocomial transmission, but the most efficient surveillance methods remain to be defined. We performed anterior nares surveillance cultures of all patients at admission to and discharge from the general internal medicine floor in our community hospital over a 7 week period, and patients completed a questionnaire on MRSA risk factors. Of the 401 patients, 41 (10.2%) had admission MRSA. Of the 48 risk measures analyzed, 10 were associated significantly with admission MRSA, and 7 of these were independently associated in stepwise logistic regression analysis. Factor analysis identified 8 latent variables that contained most of the predictive information in the 48 risk measures. Repeat logistic regression analysis including the latent variables revealed 3 independent risk measures for admission MRSA: nursing home stay (RR=6.18; 95% CI: 3.56-10.72; p<0.0001), prior MRSA infection (RR=3.97, 95% CI: 1.94-8.12; p=0.0002), and the third latent variable (Factor 3; RR=3.14; 95% CI: 1.56-6.31; p=0.0013) representing the combined effects of homelessness, jail stay, promiscuity, and intravenous or other drug use. Multivariable models had greater sensitivity for detecting admission MRSA than any single risk measure and allowed detection of 78% to 90% of admission MRSA from admission surveillance cultures on 46% to 58% of admissions. If confirmed in additional studies, multivariable questionnaire screening at admission might identify a subset of admissions for surveillance cultures that would more efficiently identify most admission MRSA.