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Shelley Chang
Skin and Environmental Contamination with Methicillin-Resistant Staphylococcus aureus in Carriers Identified Clinically
Versus Only Through Active Surveillance
Shelley Chang, Ajay K. Sethi, Brittany C. Eckstein, Usha Stiefel, Jennifer L. Cadnum, Curtis J. Donskey i
Department of Epidemiology and Biostatistics
Case Western Reserve University School of Medicine, Louis Stokes VA Medical Center
Background. Controversy exists regarding the recommendation that healthcare facilities perform active surveillance to
detect patients colonized with methicillin-resistant Staphylococcus aureus (MRSA), as it is uncertain whether patients
identified only through active surveillance represent a significant risk for transmission.
Objectives. To determine whether MRSA carriers identified only by active surveillance have a low frequency of skin and
environmental contamination when compared with patients with MRSA infection or positive clinical cultures, and to
identify factors associated with contamination.
Methods. We enrolled inpatients with MRSA nares colonization from June 2007 to June 2008. The density of nares
colonization and the frequencies of skin and environmental contamination and hand acquisition after skin contact were
compared among carriers identified only by active surveillance versus those with MRSA infection or positive clinical
cultures. Log-binomial regression was performed to determine predictors of contamination.
Results. Of 115 MRSA carriers, 57 (50%) were detected only by active surveillance. For carriers detected by active
surveillance versus clinically, the frequencies of skin and environmental contamination (47% vs. 50%, P = 0.75) and
hand acquisition (38% vs. 45%, P = 0.43) were equivalent. Bedridden status (adjusted prevalence ratio [aPR], 2.31;
95% confidence interval [CI] 1.52-3.54), increased nares density (aPR, 1.90; 95% CI 1.37-2.65), age above 65 (aPR,
1.55; 95% CI 1.09-2.20), and MRSA bacteremia (aPR, 3.91; 95% CI 1.61-9.46) were independently associated with skin
and environmental contamination. However, even ambulatory MRSA carriers age 65 or younger identified by active
surveillance had a 22% frequency of contamination.
Conclusions. Half of MRSA carriers in our institution were identified only by active surveillance. These individuals were
as likely to have skin and environmental contamination as those identified clinically, suggesting that strategies to limit
MRSA transmission must address colonized as well as infected patients.
This study was supported by the Department of Veterans Affairs and in part by the Geriatric Research Education
and Clinical Center, Cleveland Veterans Affairs Medical Center, Cleveland, Ohio.
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