FUNGUS PAECILOMYCES - A NEW AGENT IN LABORATORY-ANIMALS

The fungus Paecilomyces has not yet been considered a health problem i n laboratory animals. However, this agent known as a 'spoiler' of frui t beverages and other foodstuffs is an opportunistic pathogen especial ly in immunocompromised humans. Since 1985, we have isolated Paecilomy ces, most probably P. variotti, from six laboratory animal species, ma inly rats. In about 90% of cases the organism was localized in the res piratory tract and there are some other findings favouring the hypothe sis of an airborne infection. During this long observation period no c onsequences for the health of rats in one closed 'infected' SPF breedi ng unit (A) could be observed. In a controlled histological study on f ive infected rats, no lesions attributable to this mycotic agent could be detected. However, a self-limiting spontaneous outbreak of papular skin lesions associated with Paecilomyces was observed in a breeding colony (F) of hairless mice. The role of this fungus in an acute outbr eak of respiratory signs in another colony of conventional rats (B) wa s considered to be secondary. Bearing in mind its occasionally harmful role in humans, relatively high resistance to disinfectants and toxig enicity, this new agent should be monitored and considered a potential health risk: for laboratory animals.