Research Note Detection of Cryptococcus Neoformans in Bird Excreta

We evaluated 14 samples of bird excreta from pigeons, parrots, open billed storks and crows obtained from thirteen places in Bangkok and nearby areas between April and July 2004. These bird excreta were examined for Cryptococcus neoformans by direct plating method to inspect their ability to grow at 37oC. Capsule production was examined by Indian ink preparation. They were also tested for urease and phenoloxidase enzymes. Cryptococcus neoformans var neoformans was recovered from pigeon excreta in 9.09%. This implies those having impaired immunity may get this fungus from the environment. C. NEOFORMANS IN BIRD EXCRETA Vol 37 No. 4 July 2006 769 study. Pooled excreta were collected in each setting. Twelve areas were public areas; 11 of the 12 areas were pigeon areas, 1 was for crows, 1 was for open billed storks and another setting was a closed system farm for parrots. Detection of Cryptococcus neoformans The method performed has been described by Pal (1997) with some modifications. Ten grams of each specimen was suspended in a sterilized glass bottle containing 90 ml of sterile physiologic saline (NSS). The solution was filtered through sterile gauze cloth. The filtrate was left at room temperature for about 10 minutes. One ml of supernatant was transferred to another sterile bottle which contained 9 ml of sterile NSS, then shaken manually for 20-30 seconds. The solution was streaked onto Sabouraud’s dextrose agar containing 0.05 mg/ml of chloramphenicol. The medium was then incubated at 37oC for 48-72 hours. Round colonies with a smooth surface and cream-colored were then transferred to Pal’s medium. The medium was incubated at 37oC and examined daily for 7 days. The colonies which grew on this medium and were dark brown pigmented were stained with Indian ink. A urease test was performed and the production of phenoloxidase enzyme on GGA-DOPA medium was determined. The D-proline assimilation test was done as described by Dufait et al (1987). Colonies which were urease positive and phenoloxidase enzyme positive were considered as C. neoformans. RESULTS Of the 14 samples from thirteen areas examined for Cryptococcus neoformans. The fungus was found in only 1 sample (9.09%) of pigeon excreta, recovered on both Sabouraud’s dextrose agar and Pal’s medium.The assimilation test confirmed the fungus was C. neoformans var neoformans. The rest of the bird excreta were negative, as shown in Table 1.