Hospital outbreak of pulmonary Zygomycosis ( Mucormycosis) due to contaminated linen
January 14 2016
In a recent report, Cheng et al. (2016) discussed an outbreak of 6 pulmonary and cutaneous Mucormycosis cases within a 2 month period at Queen Mary Hospital, Hong Kong. The cause of the outbreak was found to be linen contaminated with Rhizopus. microsporus. Mucormycosis outbreaks in hospitals are extremely rare and have previously been attributed to items such as Elastoplast bandage rolls, ventilation systems, wooden tongue depressors osteomy bags, water circuitry damage and linen (1). Only 12 outbreaks worldwide in the past 43 years have been attributed to laundered linen and this is the first time pulmonary mucormycosis from contaminated linen has been reported. Recent linen-related incidents include an outbreak at the New Orleans Children’s Hospital in 2015, which led to the death of 5 children in 11 months (life news item) and two cases of rhino-cerebral mucormycosis in a paediatric oncology department due to water damage in a linen store in 2008 (2).
In the current report, 6 immunosuppressed patients were found to have developed pulmonary or cutaneous infection by Rhizopus microsporus, through direct inhalation and skin contact. The first two cases were cutaneous and therefore environmental causes such as linen items, dressing and adhesive tapes were investigated further by fungal culture. The investigators found that a high percentage of laundered linen items were positive for Mucorales, which led to a site visit and sampling at the central storage rooms. The linen supply was suspended immediately and the source of contamination was identified as the supplier, SWL. Multiple factors were found to contribute to the outbreak, including ambient temperature, lighting, ventilation and the use of the same transport for both dirty and clean linen. In addition, the measured washing machine temperature of 60ºC was different from the set temperature and was not high enough to kill the Rhizopus microsporus spores. Previous mucormycosis outbreaks have shown that contaminated linens can lead to cutaneous illness; however, the current study suggests that immunosuppressed patients may also be at risk to pulmonary mucormycosis due to inhalation of fungal spores from the contaminated linen.
Rhizopus Microsporus sporangia containing sporangiophores (source: Wikipedia).
Due to the rarity of this infection, a cluster of six infected patients within two months was a cause for concern. The authors advocate a public health consensus on the standard of hygienically clean linen items in order to prevent similar outbreaks in the future and suggest that regular microbiological testing should be introduced, along with the concept of ‘hygienically clean’ linen. Surfaces and equipment should be thoroughly cleaned, disinfected and de-dusted and this process should be compulsory and audited. In addition, the temperature sensors of washing machines should be checked regularly. Finally, there should be a clear separation of clean and dirty areas and staff to avoid cross-contamination. The lack of general hygiene standards including high dust levels and no air conditioning, contributed to the laundry failure and even post-disinfection, the site continued to contain a high percentage of positive Mucorales (40.5% of samples tested positive). The hospital in question switched to an alternative linen supplier.
Original article; Cheng et al. (2016)