Failure of the rate of nosocomial MRSA infections to decline with decreasing MRSA transmissions during universal screening

Background: MRSA is an important cause of hospital acquired infections. The Department of Veterans Affairs in 2006 mandated that all VA facilities screen all inpatients for MRSA carriage. Patients identified as being carriers were to be placed in contact precautions but routine decolonization was discouraged. Objective: Identify the effect of universal screening on occurrence of MRSA nosocomial infections in acute care patients. Methods: All patients admitted to the Buffalo DVAMC were screened by nasal swab at admission, nursing unit transfer and discharge beginning in 2007. Hospital staff were trained in proper technique for obtaining cultures. Swabs were used to inoculate chromogenic agar plates and results were reported as (+) or (-). No additional identification or genetic testing was performed. MRSA (+) patients were placed in contact precautions and compliance with hand hygiene and gown/glove use was encouraged. Routine decolonization was not attempted. Nosocomial infections were identified by established clinical and laboratory surveillance using standard CDC definitions. Bed days of care (BDOC) were obtained for the acute care units using an administrative database. The rollout period was excluded from analysis. Results: Compliance with screening was > 85%. The 2007 transmission rate was 7.9/1000 BDOC which fell to 4.4/1000 BDOC in 2008 (p=0.01). In contrast, MRSA nosocomial infections were 1.04/1000 BDOC in 2004-6 and 1.15/1000 BDOC in 2007-8 (p=0.56). Conclusions: For patients admitted to the acute care services, compliance with screening was high and recognized MRSA transmissions declined. However, MRSA nosocomial infections did not change as compared to the pre-program period. This observation may be due to the inadequacy of single site nares screening, high burden of existing multi-site colonized patients or lack of routine decolonization. Nares screening alone does not appear to decrease nosocomial MRSA infections in our patient population.