Characterization of Environmental Cryptococcus From Selected Sites in The Greater Accra Region

Abstract

Background: Cryptococcus neoformans and C. gattii affect both immunocompromised and immunocompetent individuals. Cryptococcal infections are acquired when cryptococcal spores or dehydrated yeast cells from contaminated environmental samples such as pigeon and bat droppings are inhaled. Immunocompromised individuals especially HIV/AIDS patients are however at a higher risk of death due to cryptococcosis. Sub-Saharan Africa records the greatest mortality due to cryptococcal meningitis, estimated to be as high as 70%. This study characterized Cryptococcus from pigeon and bat droppings from selected sites in the Greater Accra region. Methods: Droppings from pigeons (n=643) and bats (n=55) were collected from 4 sources (markets, church, residential quarters and a public park) from November 2016 to April, 2017. Droppings were inoculated on Sabouraud dextrose agar (SDA) supplemented with chloramphenicol (0.05 g/L). Creamy yeast colonies suggestive of Cryptococcus were purified and identified using standard microbiological methods. Microbiologically identified cryptococcal isolates were confirmed by PCR using yeast genus specific primers (ITSI and ITS4). Additionally, species specific primers (CN70 and CN49) were used to characterize the isolates. All characterized Cryptococcus were subjected to susceptibility test using two antifungal agents (fluconazole and voriconazole), referencing the Clinical Laboratory Standards Institute (CLSI), 2015 guidelines for yeast. Results: 49 of 698 (7.0%) samples were confirmed to be positive for Cryptococcus. The distributions of the isolates were as follows; church =26.3% (21/80), markets =4.9% (12/ 243) residential quarters =5.0% (16/ 320). No Cryptococcus was isolated from the droppings collected from the public park. Of the 49 Cryptococcus isolates, 1 (2.0 %) was characterized as C. gattii, (8.2 %) as C. neoformans, 20 (40.8 %) as C. neoformans /C.gatti, while 24(49.0%) of them could not be characterized with the species-specific primers used. Most of the isolates 36(73.5%) showed resistance to fluconazole. Conclusion: This study reported the presence of the pathogenic C. neoformans and C. gatti species complex from environmental sources for the first time in Accra, Ghana. A greater proportion of the species were C. neoformans with many of them resistant to fluconazole. Further studies, comparing the genetic relatedness of environmental and clinical Cryptococcus isolates is recommended.