Phospholipase activity of yeasts from wild birds and possible implications for human disease

Over the last decades, reports on yeast infections in humans have increased especially with respect to immunocompromised individuals. Phospholipases are enzymes which may be associated with pathogenic processes caused by opportunistic yeasts. Phospholipase activity (ph.a.) was investigated in 163 isolates of 13 species of yeasts. A total of 133 isolates were obtained through the screening of a total of 768 cloacae of wild birds (Group I: 182 birds of prey; Group II: 165 passeriformes and Group III: 421 other wild migratory birds), while 30 isolates were recovered from the droppings of birds housed in 32 distinct aviaries (Group IV). Phospholipase production was evaluated and quantified at 2 and 5 day pre-incubation (Pr.t) and incubation times (I.t). Isolates from cloacae (48.1%) and excreta (73.3%) produced ph.a. with the highest values registered after 5 days of I.t. Candida albicans, C. tropicalis, C. glabrata, C. lusitaniae, C. pelliculosa, Cryptococcus albidus, C. laurentii, Trichosporon beigelii, and Saccharomyces cerevisiae displayed the highest ph.a. after 2 days of Pr.t while Candida famata, C. guilliermondii and Cryptococcus neoformans after 5 days of Pr.t. Ph.a. was never found in Rhodotorula rubra isolates recovered from the cloacae of wild birds. Isolates (73.3%) from bird droppings showed a higher ph.a. than those from cloacae thus indicating that wild birds not only act as carriers but may also spread phospholipase-producing yeasts in the environment.