Survival of vancomycin-resistant Enterrococcus faecium on acrylic nails, bed linen, and plastic keyboard covers

Abstract

BACKGROUND: Vancomycin-resistant Enterococci (VRE) have emerged as a healthcare-associated pathogen in U.S. hospitals. A common mode of transmission is patient to patient, which can occur either through direct contact or through indirect contact via the hands of healthcare personnel and their frequent contact with inanimate surfaces, either preceding or following direct patient contact. This study determined the survival of VRE on acrylic fingernails, hospital bed linen, and plastic keyboard covers when suspended in an organic soil load. METHODS: Vancomycin-resistant Enterrococcus faecium ATCC 700221 and one vancomycin-resistant Enterrococcus faecium clinical isolate were grown in brain heart infusion (BHI) broth for 24 hours at 35°C. The cultures were centrifuged and resuspended in 100% fetal bovine serum. Aliquots of 10μl were inoculated onto three 3 cm × 3 cm coupons of the nails, linen, and keyboard covers. Coupons were placed into a room temperature incubator (22°C) for the duration of the study. Three coupons of each surface type were subcultured at selected time intervals over an 11-week period to determine the rate of survival. Surfaces were enumerated by vortexing the coupons for 30 seconds and performing serial dilutions and plating using BHI agar with 6μg/mL of vancomycin. In addition, coupons were incubated for 48 hours in BHI broth to determine if survivors were present at levels below the limit of detection. RESULTS: Both VRE strains survived for 11 weeks on all three surfaces tested. However, after 7 weeks, both strains were below the limit of detection on the bed linen and plastic keyboard covers. An average 3.8 log CFU reduction in both VRE strains was observed on the acrylic nails after 11 weeks. An average 4 log CFU reduction in both VRE strains was observed after 7 weeks on the bed linen and plastic keyboard covers. CONCLUSION: VRE is capable of prolonged survival on inanimate surfaces that are frequently encountered in the healthcare setting. Proper handwashing by healthcare personnel and disinfection of inanimate surfaces is important in the prevention for nosocomial transmission of VRE.