Evidence of canary droppings as an important reservoir of Cryptococcus neoformans.

After preliminary results had shown the occurrence of Cryptococcus neoformans in canary droppings in southern Italy, the increasing epidemiological interest in cryptococcosis and the habitats of the agent led to more extensive studies. 180 samples of canary droppings were collected from pet shops and private households in two towns (Messina and Reggio Calabria) of southern Italy and culturally examined for C. neoformans. The examination was carried out with the help of the brown colour effect (BCE) specific of the C. neoformans colony on Guizotia abyssinica creatinine agar (Staib agar). 48 samples (26.6%) were positive; of these, 32/108 (29.6%) were from pet shops and 16/72 (22.2%) from private households. The colony growth was not mucous, i.e. microscopically the blastospores were found to be little or not encapsulated. All C. neoformans strains tested by the auxanographic method showed a weak assimilation of creatinine. The variety status of the isolates was tested with canavanine-glycine-bromothymol-blue (CGB) agar; all strains tested (n = 420) were found to be C. neoformans var. neoformans. In the light of extensive studies on C. neoformans and the canary in the pre-AIDS era in Germany, the present observations in Italy ask for further basic research, epidemiological studies, and education of the public.