In vitro antifungal susceptibilities of Cryptococcus neoformans from pigeon droppings, cats, and human sources in Bangkok, Thailand

Introduction Cryptococcus neoformans has emerged as a clinically important opportunistic pathogen worldwide due to the AIDS pandemic. This pathogenic yeast causes pulmonary and systemic cryptococcosis in immucompromised human and susceptible animals such as cats and dogs (8, 10). C. neoformans is globally distributed and found to associate with soil, pigeon excreta, and decaying wood. Cryptococcal infections are proposed to be caused by inhalation of yeast spores in environment and these infectious propagules are deposited into the pulmonary alveoli of the hosts leading to meningitis or disseminated disease in immunodeficiency hosts (4, 7). Previously, there are several reports on isolation of C. neoformans from pigeon droppings in several provinces of Thailand such as Bangkok, Phayao, Chonburi, and Chiang Mai (5,6,11,12). Therefore it is possible that immunocompromised and immunocompetent patients could be infected with C. neoformans from the environmental sources. However, little is known about the antifungal susceptibility of C. neoformans isolated from environment even though the increased drug resistance has become a clinical concern. In this study, we aimed to determine the drug susceptibility of C. neoformans isolated from pigeon fecal droppings and cats in Bangkok, Thailand to amphotericin B, caspofungin, fluconazole, flucytosine, micafungin, and voriconazole using an automated susceptibility system.