Assessment of environmental and occupational exposure while working with multidrug resistant (MDR) fungus in an animal facility.

In less than a decade since its identification in 2009, the emerging fungal pathogen has become a major public health threat due to its multidrug resistant (MDR) phenotype, high transmissibility, and high mortality. Unlike other species, has acquired high levels of resistance to an already limited arsenal of antifungals. As an emerging pathogen, there are currently a limited number of documented murine models of infection. These animal models use inoculums as high as 10-10 cells per mouse, and the environmental and occupational exposure of working with these models has not been clearly defined. Using real-time quantitative polymerase chain reaction (PCR) and culture, we monitored the animal holding room as well as the procedure room for up to 6 months while working with an intravenous model of infection. This study determined that shedding of the organism is dose-dependent, as detectable levels of were detected in the cage bedding when mice were infected with 10 and 10 cells, but not with doses of 10 and 10 cells. Autoclaving bedding in closed micro-isolator cages was found to be an effective way to minimize exposure for animal caretakers. We found that tissue necropsies of infected mice were also an important source of potential source exposure to . To mitigate these potential exposures, we implemented a rigorous "buddy system" workflow and a disinfection protocol that uses 10% bleach followed by 70% ethanol and can be used in any animal facility when using small animal models of infection.