Long-term survival curve of methicillin-resistant Staphylococcus aureus on clinical contact surfaces in natural-like conditions

We investigated methicillin-resistant Staphylococcus aureus (MRSA) survival on a noncritical environmental surface in real-life conditions (dental chair located in a box of a Dentistry Department, subjected to microclimate variations and presence of people) and with a plausible baseline inoculum (5-log colony-forming units) in contrast to survival that has been frequently tested in laboratory conditions and/or using high baseline levels. We tested 5 freshly isolated sporadic strains and observed a drastic MRSA fall (>90%) 15 minutes after exposure to the environment. After 4 months, we detected MRSA at very low levels in 9 out of 25 tests. The MRSA survival curve showed that the velocity of log count decrease, highest soon after exposure, tended to decrease progressively. Thus, whereas the risk for infection through shared surfaces is probably minimal, the risk for MRSA diffusion in the community is high. Copyright (c) 2012 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.