Urban pigeons (Columba livia) as a potential source of pathogenic yeasts: a focus on antifungal susceptibility of Cryptococcus strains in Northeast Brazil.

To investigate pigeons as a potential source of pathogenic yeast species, 47 samples of pigeon droppings and 322 samples from pigeon cloacae were evaluated. The samples were also collected from trees located near the pigeon habitats, in the city of Fortaleza, Ceará, Northeast Brazil. In addition, we evaluated the in vitro antifungal susceptibility of these environmental Cryptococcus strains to amphotericin B, azoles and caspofungin. C. neoformans var. neoformans (n = 10), C. laurentii (n = 3), Candida spp. (n = 14), Rhodotorula mucilaginosa (n = 6) and Trichosporon sp. (n = 3) were isolated from pigeon droppings. In contrast, only Candida spp. (n = 4), Trichosporon sp. (n = 3) and R. mucilaginosa (n = 2) were recovered from cloacae specimens. Only Candida glabrata (n = 1) was recovered from plant samples. Azole resistance was detected in only one environmental strain of Cryptococcus, which was resistant to itraconazole (MIC = 1 microg/ml). As expected, all Cryptococcus strains were resistant to caspofungin. In summary, the present study confirms that urban pigeons are a potential source of Cryptococcus spp. and other pathogenic yeasts. Additionally, antifungal resistance was observed in one environmental strain of Cryptococcus neoformans var. neoformans in Northeast Brazil.