A prospective study to examine the epidemiology of methicillin-resistant Staphylococcus aureus and Clostridium difficile contamination in the general environment of three community hospitals in southern Ontario, Canada

Abstract

Background: The hospital environment has been suggested as playing an important role in the transmission of hospital-associated (HA) pathogens. However, studies investigating the contamination of the hospital environment with methicillin-resistant Staphylococcus aureus (MRSA) or Clostridium difficile have generally focused on point prevalence studies of only a single pathogen. Research evaluating the roles of these two pathogens, concurrently, in the general hospital environment has not been conducted. The objectives of this study were to determine the prevalence and identify risk factors associated with MRSA and C. difficile contamination in the general environment of three community hospitals, prospectively.

Methods: Sampling of environmental surfaces distributed over the medicine and surgical wards at each hospital was conducted once a week for four consecutive weeks. Sterile electrostatic cloths were used for environmental sampling and information regarding the surface sampled was recorded. For MRSA, air sampling was also conducted. Enrichment culture was performed and spa typing was performed for all MRSA isolates. For C. difficile, isolates were characterized by ribotyping and investigated for the presence of toxin genes by PCR. Using logistic regression, the following risk factors were examined for MRSA or C. difficile contamination: type of surface sampled, surface material, surface location, and the presence/absence of the other HA pathogen under investigation.

Results: Overall, 11.8% (n=612) and 2.4% (n=552) of surfaces were positive for MRSA and C. difficile, respectively. Based on molecular typing, five different MRSA strains and eight different C. difficile ribotypes, including ribotypes 027 (15.4%) and 078 (7.7%), were identified in the hospital environment. Results from the logistic regression model indicate that compared to computer keyboards, the following surfaces had increased odds of being contaminated with MRSA: chair backs, hand rails, isolation carts, and sofas.

Conclusions: MRSA and C. difficile were identified from a variety of surfaces in the general hospital environment.Several surfaces had an increased risk of being contaminated with MRSA but further studies regarding contact rates, type of surface material, and the populations using these surfaces are warranted.

Figure 1

Mean predicted probability for MRSA to be cultured from surfaces in the general environment. * Surfaces include: antibacterial wipes container, brochure holder, bulletin board, chart holder, clip board, door knob, glove box holder, heating oven handle, lamp shade, lifter handle, sofa pillow, urine collection container, visiting room – air.