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Melanin is an important virulence factor for several microorganisms, including Cryptococcus neoformans sensu lato and Cryptococcus gattii sensu lato, thus, the assessment of melanin production and its quantification may contribute to the understanding of microbial pathogenesis. The objective of this study was to standardise an alternative method for the production and indirect quantification of melanin in C. neoformans sensu lato and C. gattii sensu lato. Eight C. neoformans sensu lato and three C. gattii sensu lato, identified through URA5 methodology, Candida parapsilosis ATCC 22019 (negative control) and one Hortaea werneckii (positive control) were inoculated on minimal medium agar with or without L-DOPA, in duplicate, and incubated at 35°C, for 7 days. Pictures were taken from the third to the seventh day, under standardised conditions in a photographic chamber. Then, photographs were analysed using grayscale images. All Cryptococcus spp. strains produced melanin after growth on minimal medium agar containing L-DOPA. C. parapsilosis ATCC 22019 did not produce melanin on medium containing L-DOPA, while H. werneckii presented the strongest pigmentation. This new method allows the indirect analysis of melanin production through pixel quantification in grayscale images, enabling the study of substances that can modulate melanin production., (© 2017 Blackwell Verlag GmbH.)

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.