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Updated: May 3, 2026
Broth Microdilution In Vitro Screening: An Easy and Fast Method to Detect New Antifungal Compounds
Published on: February 14, 2018
Environmental isolation, biochemical identification, and antifungal drug susceptibility of Cryptococcus species
Valter Luis Iost Teodoro1, Fernanda Patrícia Gullo1, Janaína de Cássia Orlandi Sardi1
1Departamento de Análises Clínicas, Laboratório de Micologia Clínica, Faculdade de Ciências Farmacêuticas, Universidade Estadual Paulista (UNESP), AraraquaraSP, Brasil.
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.
Insights
Pathogenic Cryptococcus, a fungus causing cryptococcosis, was found in 66.6% of pigeon droppings in Araraquara. Fortunately, no antifungal resistance was detected in the identified Cryptococcus species.
Area of Science:
- Medical Mycology
- Environmental Microbiology
- Public Health
Background:
- Opportunistic fungal infections, particularly cryptococcosis, are a growing public health concern.
- Cryptococcosis poses a significant risk to individuals with compromised immune systems, such as those with human immunodeficiency virus (HIV).
Purpose of the Study:
- To investigate the prevalence of pathogenic Cryptococcus in pigeon excrement within Araraquara.
- To identify Cryptococcus species and assess their susceptibility to key antifungal medications.
Main Methods:
- Collection of 87 bird dropping samples from diverse urban environments in Araraquara.
- Isolation and identification of Cryptococcus using classical microbiological tests on Niger agar.
- Antifungal susceptibility testing against fluconazole, itraconazole, voriconazole, and amphotericin B.
Main Results:
- A high occurrence of Cryptococcus was detected, with 66.6% of samples testing positive.
- Identified species included Cryptococcus neoformans (17.2%) and Cryptococcus gattii (5.2%), among others.
- A significant portion (70.7%) of isolates were identified only to the genus level (Cryptococcus spp.).
Conclusions:
- No observed resistance to the tested antifungal drugs among the isolated Cryptococcus strains.
- Effective epidemiological control of cryptococcosis necessitates identifying infested areas and implementing bird control and environmental disinfection measures.
