Environmental isolation, biochemical identification, and antifungal drug susceptibility of Cryptococcus species

Introduction The incidence of opportunistic fungal infections has increased in recent years and is considered an important public health problem. Among systemic and opportunistic mycoses, cryptococcosis is distinguished by its clinical importance due to the increased risk of infection in individuals infected by human immunodeficiency virus. Methods To determine the occurrence of pathogenic Cryptococcus in pigeon excrement in the City of Araraquara, samples were collected from nine environments, including state and municipal schools, abandoned buildings, parks, and a hospital. The isolates were identified using classical tests, and susceptibility testing for the antifungal drugs (fluconazole, itraconazole, voriconazole, and amphotericin B) independently was also performed. After collection, the excrement samples were plated on Niger agar and incubated at room temperature. Results A total of 87 bird dropping samples were collected, and 66.6% were positive for the genus Cryptococcus. The following species were identified: Cryptococcus neoformans (17.2%), Cryptococcus gattii (5.2%), Cryptococcus ater (3.5%), Cryptococcus laurentti (1.7%), and Cryptococcus luteolus (1.7%). A total of 70.7% of the isolates were not identified to the species level and are referred to as Cryptococcus spp. throughout the manuscript. Conclusions Although none of the isolates demonstrated resistance to antifungal drugs, the identification of infested areas, the proper control of birds, and the disinfection of these environments are essential for the epidemiological control of cryptococcosis.引言 近年来，机会性真菌感染的发病率持续攀升，已被视为重要的公共卫生问题。在系统性真菌病与机会性真菌病中，隐球菌病因人类免疫缺陷病毒（human immunodeficiency virus, HIV）感染者的感染风险显著升高，而具有突出的临床意义。 方法 为探明阿拉拉夸拉市（Araraquara）鸽粪中致病性隐球菌（Cryptococcus）的检出情况，研究人员从9类环境中采集样本，涵盖公立学校、市属学校、废弃建筑、公园及医院。研究采用经典鉴定方法对分离菌株进行鉴定，并分别开展了针对氟康唑（fluconazole）、伊曲康唑（itraconazole）、伏立康唑（voriconazole）与两性霉素B（amphotericin B）这4种抗真菌药物的药敏试验。样本采集完成后，接种于尼日尔琼脂（Niger agar）平板，置于室温条件下培养。 结果 本研究共采集87份鸟类粪便样本，其中66.6%的样本隐球菌属（Cryptococcus）检测结果呈阳性。共鉴定出以下菌种：新生隐球菌（Cryptococcus neoformans，占比17.2%）、格特隐球菌（Cryptococcus gattii，占比5.2%）、暗色隐球菌（Cryptococcus ater，占比3.5%）、劳伦隐球菌（Cryptococcus laurentti，占比1.7%）以及浅白隐球菌（Cryptococcus luteolus，占比1.7%）。另有70.7%的分离株未鉴定至种水平，本文中统一记为隐球菌属（Cryptococcus spp.）。 结论 尽管所有分离菌株均未表现出对上述抗真菌药物的耐药性，但明确污染区域、合理管控鸟类种群以及对相关环境开展消毒工作，对于隐球菌病的流行病学防控仍具有至关重要的意义。