Cheng VC, Chen JH, Wong SC, Leung SS, So SY, Lung DC, Lee WM, Trendell-Smith NJ, Chan WM, Ng D, To L, Lie AK, Yuen KY.; Clin Infect Dis. 2015 Dec 13. pii: civ1006. [Epub ahead of print]
BACKGROUND: Healthcare laundry-related infection is rare and pulmonary zygomycosis due to contaminated hospital linens has never been reported.
METHODS: We reported an outbreak investigation of zygomycosis in a university-affiliated teaching hospital. Air samplers, sponge swabs and Replicate Organism Detection And Counting (RODAC) contact plates were used for environmental sampling. The fungal isolates from clinical and environmental samples were identified by morphology, MALDI-TOF MS, and ITS1-5.8S-ITS2 rRNA gene cluster sequencing.
RESULTS: From 2 June 2015 to 18 July 2015, six immunosuppressed patients developed pulmonary (n=4) and/or cutaneous (n=3) infection by a spore-forming mold, Rhizopus microsporus, through direct inhalation and skin contact of contaminated linen items supplied by a designated laundry. Seventy (27.8%) of 252 freshly laundered clothing and 15 (3.4%) of 443 non-clothing laundered linen items (pillow case, bed sheet, draw sheet) were contaminated by R. microsporus, which was significantly higher than those from other hospital laundries (0%, n=451; p<0.001) supplying linen to hospitals with no cases of zygomycosis reported during the same period. The fungal isolates from patients and linens were phylogenetically related. Sixty-one percent of environmental samples and 100% of air samples at the designated laundry were also positive for zygomycetes, suggesting heavy environmental contamination. RODAC contact plates revealed mean total viable bacteria counts of freshly laundered items (1028 +/- 611 CFU/100cm2) far exceeded the "hygienically clean" standard of 20 CFU/100cm2 set by the US healthcare textile certification requirement.
CONCLUSIONS: Suboptimal conditions of washing, drying, and storage contributed to the massive linen contamination and the outbreak of zygomycosis.