ISOLATION AND DETECTION OF CRYPTOCOCCUS NEOFORMANS FROM PIGEON DROPPINGS: ISFAHAN AND IT"S SUBURBS PROVINCE PIGEON TOWERS

Abstract

Introduction: Cryptococcus neoformans is an encapsulated yeast like and a principle cause of morbidity and mortality in immunocompromised hosts, especially those with AIDS. At the persent, due to progressive increase in predisposing factors to cryptococcosis and proper therapy, identification of this fungus has become more important than before. The most important sources of infection are contaminated pigeon droppings and soil. Since there are many so called .Pigeon Tower" in Isfahan and it"s suburbs, we decided to isolate and identify C.neoformans from pigeon droppings collected in these towers. It is notable that these pigeon droppings are traditionally used as natural fertilizer.
Methods: After preparing suspensions of droppings, we spread them onto the surface of Niger seed agar and L-DOPA containing media. The identification of isolates was established by ureas test, India ink preparation, subculturing on CMA + Tween 80 medium, growth 37°c and assimilation of carbohydrates and nitrate. GCP (Glycine- Cyclohexaamide - Phenol red) medium was used for distinguishing C.neoformans Var. neoformans from C. neoformans Var. gattii. The pathogenicity of the isolates was determined in mice by intracerebral inoculation.
Results: c. neoformans was isolated from 11 of 136 samples (8.1 percent). All of them were identified as c. neoformans Var. neoformans. However, five of them (45.5 percent) caused disease in mice. There was no statistically significant relation between the pH of the pigeon dropping and the precence of C.neoformans.
Discussion: According to the results, it seems that the actual prevalance of cryptococcosis should be more than the reported cases. Regarding the relative frequency of the yeast in "Pigeon Towers" in Esfahan, as it was shown in this study, clinicians should pay more attention to this organism and its disease, especially in patients with predisposing factors.