infection control and hospital epidemiology june 2010, vol. 31, no. 6 original article Occurrence of Skin and Environmental Contamination with Methicillin-Resistant Staphylococcus aureus before Results of Polymerase Chain Reaction at Hospital Admission Become Available Shelley Chang, PhD; Ajay K. Sethi, PhD, MHS; Usha Stiefel, MD; Jennifer L. Cadnum, BS; Curtis J. Donskey, MD background. Active surveillance to detect patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) is increasingly practiced in healthcare settings. However, inpatients may already become sources of transmission before appropriate precautions are implemented. objective. To examine the frequency of MRSA contamination of commonly touched skin and environmental surfaces before patient carriage status became known. methods. We conducted a 6-week prospective study of patients who were identified by use of polymerase chain reaction (PCR) at hospital admission as having nasal MRSA colonization. Skin and environmental contamination was assessed within hours of completion of PCR screening. results. There were 116 patients identified by PCR screening as having nasal MRSA colonization during the period from mid-April to May 2008, of whom 83 (72%) were enrolled in our study. Overall, MRSA was detected on the skin of 38 (51%) of 74 patients and in the environment of 37 (45%) of 83 patients. Of 83 environmental culture samples, 63 (76%) were obtained within 7 hours after PCR results became available, and 73 (88%) were obtained before wards were notified of PCR results. Of the 83 MRSA-colonized patients, 15 (18%) had contaminated their environment 25 hours after admission, and 29 (35%) had contaminated their environment 33 hours after admission. Thirty-two (39%) of the 83 patients had roommates, 13 (41%) of whom contaminated their environment. The median interval from admission to PCR result was 20 hours, and the median interval from PCR result to notification was 23 hours. An increased quantity of MRSA cultured from a nasal sample was significantly associated with contamination. conclusions. Before any contact precautions can be implemented, newly identified MRSA carriers frequently have contaminated their environment with MRSA and have contamination of commonly examined skin sites. In hospitals that perform active surveillance, strategies are needed to minimize delays in screening or to preemptively identify patients at high risk for disseminating MRSA. Infect Control Hosp Epidemiol 2010; 31(6):607-612 From the Department of Epidemiology and Biostatistics, Case Western Reserve University School of Medicine (S.C., A.K.S.), and Research Service (U.S., J.L.C., C.J.D.) and the Geriatric Research Education and Clinical Center (C.J.D.), Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio. Received July 27, 2009; accepted November 26, 2009; electronically published April 16, 2010.  2010 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2010/3106-0008$15.00. DOI: 10.1086/652775 Active surveillance to detect patients colonized with methi- cillin-resistant Staphylococcus aureus (MRSA) is increasingly practiced in healthcare settings. Because colonized patients are at risk for infection, screening to identify asymptomatic carriers of MRSA can be used to facilitate preventive strategies such as decolonization of high-risk individuals. 1,2 In addition, some experts and policy makers recommend routine screen- ing to identify carriers so that they can be placed under con- tact precautions to prevent transmission. 3,4 A potential lim- itation of active surveillance as an infection control strategy for MRSA is that, after an MRSA carrier is admitted to the hospital, there may be significant delays before that patient is placed under contact precautions. Use of molecular screen- ing methods may reduce, but not eliminate, delays in iden- tifying MRSA carriers. 5 Beginning in October 2007, the Department of Veterans Affairs mandated that all acute care facilities perform active surveillance for MRSA carriage for all patients at hospital admission, ward transfer, and hospital discharge. 6 To facilitate rapid identification of carriers, use of a polymerase chain reaction (PCR) method was instituted for admission screen- ing. Here, we examined the time from hospital admission to notification of positive results of MRSA screening by PCR in a Veterans Affairs hospital and tested the hypothesis that many patients have already become sources of MRSA trans- mission before appropriate precautions are implemented.