MASSIVE FUNGAL CONTAMINATION IN ANIMAL CARE FACILITIES TRACED TO BEDDING SUPPLY

During the course of immunologic studies involving the gastrointestina l colonization of mice with Candida albicans, it became apparent that the animals were being exposed to large numbers of Aspergillus fumigat us spores which interfered with the C. albicans colonization, To deter mine the source of the A. fumigatus exposure and the extent of fungal contamination of the medical school vivarium and four satellite facili ties, fungal analyses of feed, bedding, and air were undertaken, Initi al samples from the air were collected with 3-h settle plates; air sam pling following cleanup was done with an Andersen air sampler. The sou rce of contamination in the mouse rooms was determined to be Beta Chip bedding, which came from the manufacturer highly contaminated. Beta C hip bedding (1 g) obtained from the manufacturer just prior to testing contained 10(4) CFU of A, fumigatus, 20 CFU of a zygomycete, and 10 C FU of a Penicillium sp, Coarse-grade Beta Chip had approximately one h alf those levels of contamination, Puree Cob bedding was highly contam inated also, but with a Fusarium sp, and a Cladosporium sp, Untreated and heat-treated Sani-Chip as well as all other heat-treated preparati ons obtained from the manufacturer contained no detectable spores, Rod ent chow direct from the manufacturer had no A. fumigatus, although it did contain 150 CFU of fungus per g, including 80 CFU of a Rhodotorul a sp., 60 CFU of Cryptococcus uniguttulatus, and 1 CFU of a Penicilliu m sp. Unopened laboratory canine, feline diet, rabbit, and guinea pig chow, however, had 1.5 x 10(2) to 4.1 x 10(2) CFU of A. fumigatus per g. Air sampling confirmed the presence of numerous A. fumigatus spores prior to cleanup and the absence or significant reduction in spore nu mbers after cleanup with Quatricide PV. These data emphasize the need to examine support materials for:microbial contamination prior to thei r use, especially with research animals being used for microbiologic a nd immunologic studies, It is recommended that Sani-Chip or heat-treat ed preparations other than Sani-Chip be used for the housing of rodent s.