A REVIEW ON ISOLATION OF Cryptcoccus neoformans var neoformans FROM PIGEON DROPPINGS IN KATHMANDU VALLEY

This research is going on in the research laboratory of the Kathmandu College Of Science and Technology under the supervision of Prof. Prahlad Raj Pant  , Mrs. Archana Katuwal, Mrs. Jyoti Amatya and Mrs. Ganga GC with a team of five students completing MSc. Microbiology II part.

This research is persued to find  the prevalence of  Cryptococcus neoformans from
environmental sample dry and weathered pegeon excreta collected in between the months of March-June 2009 from different major sites of the valley mostly inhabited by pigeons. The samples were processed on the same day of collection. 

The fungi was isolated in primary isolation medium, Sabouraud’s Dextrose Agar (SDA) with Chloramphenicol following standard procedure (with slight modification of M. Pal 1997). Pure isolates were subcultured on Staib’s medium along with control plate of SDA.. Identification of the opportunistic fungal pathogen was done on the basis of its ability to grow at temperature of 370C as well as 250C, urease production and growth on Staib’s agar followed by demonstration of basidiospores and capsulated budding yeastlike fungi under microscope. Till date the research has been commenced for 75 samples out of total 80 samples; with a positive rate of 6/75 (8%).

Cryptococcus neoformans is an encapsulated round to oval yeastlike fungus causing crptococcosis, and measuring 4 to 6 microns. A characteristic polysaccharide capsule of variable thickness (1 to 30 microns) surrounds these yeasts. In its natural enviroment the capsule is thinner and the yeast smaller, while thicker capsules tend to be found from infected tissues. The polysaccharide capsule, the phenoloxidase enzyme of Cryptococcus neoformans, and the organism's ability to grow at 37°C, are its major virulence factors
Cryptococcosis is caused by 2 species in the genus Cryptococcus, C. neoformans and C. gattii (1). C. neoformans (serotypes A, D, and AD) is found worldwide and causes cryptococcosis most frequently in immune deficient humans, such as in patients with HIV / AIDS. The infection may cause meningitis in the lungs, skin or other body regions. The most common clinical form is meningoencephalitis. It is caused by inhaling the fungus found in soil that has been contaminated by pigeon droppings.