Evaluation of the Efficacy of a Conventional Cleaning Regimen in Removing Methicillin-Resistant Staphylococcus aureus From Contaminated Surfaces in an Intensive Care Unit

Abstract

The efficacy of daily level 2 cleaning (i.e., environmental decontamination of a room or bed space using detergents to clean and 1% hypochlorite solution to disinfect the area) in eliminating methicillin-resistant Staphylococcus aureus (MRSA) from environmental sampling sites touched by MRSA-positive patients, their visitors and/or the health care workers (HCWs) was investigated. The study was conducted during April 2006-March 2007 in the intensive care unit (ICU) of Antrim Area Hospital, Northern Ireland, UK. During the first 9 months, samples were collected from the sites immediately prior to the level 2 cleaning and every hour after the level 2 cleaning for up to 7 h. Consideration of the results obtained during this period led to an increase in sampling intervals during the last 3 months of the study (i.e., samples were obtained 1, 3 and 5 h after the cleaning). 37 MRSA-positive patients were identified, and environmental screening was performed for 14 of these patients. MRSA was recovered from environmental sites for 6 patients before and/or after the level 2 cleaning. For the remaining 8 patients, MRSA was not recovered from any samples collected before or after the level 2 cleaning. For 3 patients, MRSA isolates with identical pulsed field gel electrophoresis profiles were recovered from both the patient and the environment. For the remaining 3 patients, the isolates recovered from the patient differed from those found in the environment. For almost all sampling sites, the first samples obtained after level 2 cleaning (i.e., the 1-h samples) were MRSA negative, suggesting that such cleaning is effective in removing MRSA from the immediate environment of colonized patients. The contaminated sites included drawer handles, drip counters, Baxter or infusion pumps for central vascular catheters, syringe drivers, and a ventilator panel and/or screen. Majority of the contaminated sites were those that only HCWs would have touched, suggesting that environmental contamination was likely to have originated from HCWs. It is concluded that the level 2 cleaning can be effective in removing MRSA from a range of environmental sites that are high risk of patient and/or HCW hand contact in critical areas such as ICUs. However, in the absence of any residual cleaning and/or disinfectant effects, the clear beneficial effects of such interventions are transient and rapidly negated by subsequent failures in infection control practice.