Infection Control


Paolo Uy, Dick Zoutman Queen’s University, Kingston, Ontario, Canada

As Presented by Dr. Zoutman at the CHICA 2010 Conference in Vancouver BC

Transmission of MRSA and VRE on hospital surfaces is increasingly recognized. Chemical cleaning methods are time consuming, subject to variability in use, contact time and have the potential for toxicity and ecosystem impacts.

This study was designed to determine the efficacy of a steam sterilization system in eliminating MRSA and VRE from hospital high touch surface materials.

High quality dry steam was produced using a SteamKing(R) 1500 commercial steamer with thermal accelerated nanocrystal sanitation technology. 2 cm test discs were machined from tabletop laminate, toilet seat plastic and stainless steel door handles. Discs were sterilized and inoculated with high concentrations of MRSA and VRE cultures prepared in tryptic soy broth. After drying, the test surfaces were exposed to steam using the system’s hose and 4 cm nylon brush for 5 seconds, immediately after which the residual bacterial inoculum was eluted in saline, serially diluted and quantitatively plated in duplicate to allow colony counts. Inoculated but nonsteamed test discs served as controls.

The initial inoculum of MRSA and VRE dried and eluted from the test disc surfaces averaged 1 x106cfu/disc. After a 5 second steam exposure the test discs revealed a 6 log10 reduction compared to the control untreated discs for both MRSA and VRE on all three test surface materials. We conclude that steam exposure results in a 6-log reduction of MRSA and VRE on heavily contaminated surface materials used in hospitals quickly and efficiently.

Featured in the PIDAC Best Practices Document Environmental Cleaning for Prevention and Control of Infections, this is a new and evolving technology for hospital disinfection.

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