A New screening medium for environmental recovering of Cryptococcus neoformans/C. gattii species complex

Abstract

Cryptococcus neoformans is the most common causative agent of fungal meningitis in human especially AIDS patients. Avian droppings in commits areas are considered as an environment reservoir for this organism. In this study, we developed a new screening medium, the red holy basil extract agar, for environmental survey of the yeast. The new medium successfully induced melanin production of C. neoformans controls but not in Candida spp. For a field test, fifty-three avian droppings were collected from 37 districts around Bangkok, Thailand. Twenty yeast isolates were recovered on the red holy basil extract agar and, subsequently, identified by using conventional biochemical methods and URA5RFLP. Nineteen isolates from six districts were identified as C. neoformans, VNI molecular type and one isolate from one district were identified as Cryptococcus spp. The new screening medium, red holy basil extract agar, is affordable in Thailand as the raw material can be readily found in local market and inexpensive. Moreover, the high prevalence of the VNI molecular type are in line with all previous cryptococcal epidemiological studies in Asia. However, further molecular genotyping antifungal drug susceptibility and strains samplings are warranted to monitor an emergence of any high virulent genotype.