A Pragmatic Approach to Investigating Nosocomial Acquisition of Rare and Emerging Molds

Invasive mold disease is associated with high mortality in immunosuppressed patients. While Aspergillus spp. and the Mucorales are well known, several other molds have emerged that cause infections and even outbreaks in susceptible hosts. These include Fusarium spp., Scedosporium spp., Lomentospora prolificans, and several others. The principles of preventing nosocomial mold infections include use of high-efficiency particulate air filters, removal of any potential sources of contamination, and risk-assessment of construction sites in adjacent areas. However, there is limited information on the approaches to assessment and management of outbreaks when there is a cluster of rare mold infections. The incubation period of rare and emerging molds is unknown and ascertaining whether the origin is nosocomial or community-acquired is difficult. Surveillance may be required to determine whether cases are part of an ongoing problem. The environmental niches of the rare molds are unique; e.g., Fusarium spp. are associated with hospital water distribution systems. They also cause outbreaks of fungal keratitis. Many rare molds are seen in cases of medicinal product contamination and managing such outbreaks requires support from and coordination by national agencies. Environmental precautions around patients and construction activities should be reassessed during outbreaks. A systematic approach is required when evaluating a cluster or even an isolated nosocomial case. Surveillance systems should be strengthened. This review summarizes the information available on outbreaks of rare and emerging molds. We further discuss a set of actions that may be undertaken in the event of an outbreak.