Karen E. Michael

Project title: Assessment of Environmental Contamination with Three Pathogens in a Hospital Laundry Facility

Degree: PhD | Program: Environmental and Occupational Hygiene (EOHY) | Project type: Thesis/Dissertation
Completed in: 2016 | Faculty advisor: Marilyn C. Roberts


Very little is known about the environmental contamination, due to soiled clinical linens, of hospital laundry facilities. To study this environment, an exposure assessment was performed at an industrial clinical laundry facility in Seattle, WA, USA. Surface swab samples (n=240) from the environment were collected from the facility over four time periods in 2015. These samples were cultured for three pathogens; Clostridium difficile, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Isolates were characterized by various methods including antibiotic resistance, presence of toxin producing genes, Multilocus sequence typing, 16S sequencing and/or SCCmec typing. Voluntary participation among the employees consisted of nasal swabs for detection of MRSA, observations during their work and questionnaires. Odds of finding surface contamination with ≥ 1 pathogen were calculated. Contamination with all three pathogens was observed in the facility in both dirty and clean areas. The dirty area had a higher odds ratio than the clean area for overall contamination (≥1 pathogen) (OR=18.0). The odds ratios of individual pathogen presence varied for C. difficile (OR=15.5), MRSA (OR=14.8) and VRE (OR=12.6). The highest odds of finding surface contamination occurred in the primary and secondary sort areas where dirty linens are manually sorted by employees (OR=63.0, p<0.001). MRSA nasal contamination was identified in 5/23 (22%) employees, with four out of five working in the dirty area. Improved protocols for prevention and reduction of environmental contamination as well as occupational exposure were implemented as a result of this study.