Isolation and Characterization of Cryptococcus neoformans Varieties Recovered from Natural Sources in Bogotá, Colombia, and Study of Ecological Conditions in the Area

Abstract

Cryptococcus neoformans, the etiological agent of cryptococcosis, has been associated with avian droppings and certain trees in different countries, including Colombia. C neoformans environmental isolates were obtained in urban areas in Bogotá, Colombia, and the strains recovered were phenotypically characterized. Attempts to determine the ecological conditions (micro- and macroclimatic) possibly related to their habitat were also undertaken. Four hundred and eighty samples from bark, soil around trunk bases, and detritus inside hollows of 32 trees were collected in three urban areas during a 5-month period, as well as 89 avian droppings samples from different places. Of plant samples, 6.7% collected from nine tree species yielded C. neoformans var. gattii, serotype B strains in 99% of the cases, and C. neoformans var. grubii, serotype A in 1%. The yeast was more frequently recovered from bark than from soil or detritus inside hollows, and from trees with hollows or rotted wood rather than from trees in which birds nest. C. neoformans was present with higher frequency and density in the rainy season than in the dry season; we found that slightly higher temperature and humidity values of the microhabitat, as compared to those of the environment, favored fungal occurrence, but the phenological state of the tree did not. Of dropping samples, 7.9% yielded C. neoformans strains, all of them C. neoformans var. grubii, serotype A. The yeast was obtained more frequently from dry droppings than from moist ones, but neither the sunlight exposure nor the site of collection of samples was correlated with this occurrence. Population density was significantly higher in droppings than in tree samples. Under laboratory conditions, isolates of different serotype showed similar capsular sizes. Water content and pH ranges were wide and did not show any significant difference between positive and negative samples.

Primer aislamiento ambiental de Cryptococcus gattii de serotipo B, en Cúcuta, Colombia

“…Compared with other studies where C. gattii had been found in 27.5% and 99% of the sampled trees, and the recovery was between 50 and 15 x 10 6 cfu/g of sample (16,33) and C. neoformans had been recovered among 7.9% and 14% of the samples, with a recovery between 50 and 1x10 7 cfu/g of sample (33,34), in our study, only 0.07% of the samples processed were positive for C. neoformans/C. gattii species complex.…”

Cryptococcus neoformans isolation from swallow (Hirundo rustica) excreta in Iran

“…Although pigeon droppings have been documented as the major source of C. neoformans in nature, the presence of this yeast in many bird species other than pigeons, i.e., dove, psitaccines, budgerigars, canaries, parrots, cockatoos and starlings had also been reported 2,7,13,20,21,25 . In previous studies from Iran, C. neoformans was also isolated in 17.8% 10 and 34% 28 of pigeon droppings.…”

ANaganishiain high places: functioning populations or dormant cells from the atmosphere?

“…For example, Cryptococcus gatti was traditionally considered to be restricted to tropical and subtropical climates; however, there is increasing evidence that it can be dispersed via the atmosphere even to colder areas such as the Northwest USA (Kidd et al 2004; Byrnes et al 2010). Other investigations into the ecological niches of these opportunistic pathogens have revealed a global distribution (Chen et al 2014) often associated with reservoirs such as guano (Nielsen et al 2007), Eucalyptus trees (Ellis and Pfeiffer 1990a), and Cassia trees (Lazera et al 2000; Granados and Castañeda 2005). Furthermore, air sampling in Australia during the flowering season of Eucalyptus camaldulensis contained C. gattii (Ellis and Pfeiffer 1990b) as did air samples collected after tree-cutting activities in Canada (Kidd et al 2007).…”