The expanding host tree species spectrum ofCryptococcus gattiiandCryptococcus neoformansand their isolations from surrounding soil in India

Abstract

This study reports the widespread prevalence of Cryptococcus neoformans and Cryptococcus gattii in decayed wood inside trunk hollows of 14 species representing 12 families of trees and from soil near the base of various host trees from Delhi and several places in the Indian states of Uttar Pradesh, Haryana, Tamil Nadu and Chandigarh Union Territory. Of the 311 trees from which samples were obtained, 64 (20.5%) were found to contain strains of the C. neoformans species complex. The number of trees positive for C. neoformans var grubii (serotypeA) was 51 (16.3%), for C. gattii (serotype B) 24 (7.7%) and for both C. neoformans and C. gattii 11 (3.5%). The overall prevalence of C. neoformans species complex in decayed wood samples was 19.9% (111/556). There was no obvious correlation between the prevalence of these two yeast species and the species of host trees. The data on prevalence of C. gattii (24%) and C. neoformans (26%) in soil around the base of some host trees indicated that soil is another important ecologic niche for these two Cryptococcus species in India. Among our sampled tree species, eight and six were recorded for the first time as hosts for C. neoformans var grubii and C. gattii, respectively. A longitudinal surveillance of 8 host tree species over 0.7 to 2.5 years indicated long term colonization of Polyalthia longifolia, Mimusops elengi and Manilkara hexandra trees by C. gattii and/or C. neoformans. The mating type was determined for 153 of the isolates, including 98 strains of serotype A and 55 of serotype B and all proved to be mating type alpha (MAT alpha). Our observations document the rapidly expanding spectrum of host tree species for C. gattii and C. neoformans and indicate that decayed woods of many tree species are potentially suitable ecological niches for both pathogens.

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

“…grubii from the same place, like the co-distribution of different genotypes or serotypes found in previous studies (27,28,32) could suggest a related introduction and dispersal mechanisms or synergistic colonization considering that in some cases the populations could be very complex.…”

“…In addition, the findings of this study increase the number of reports of the recovering of C. gattii from the environment, although it was not possible to associate the isolate with a specific tree species, because the isolate was recovered from soil, in contrast to previous studies of ecological reservoirs of C. gattii, in which associations between the yeast and different trees species had been found due to the recovering of the yeast from vegetable parts (14)(15)(16)(17)27,28). However, our results show that the soil is the sample that is harboring the fungus, while the other tree material was negative, possibly because most of the samples were taken from soil (82.8%), but suggesting that the soil is one of the main reservoirs of colonization for this pathogen, and therefore, the fungus may be interacting with non-vertebrate hosts as nematodes and amoebae, as suggested by Casadevall et al (29).…”

In vitro antifungal susceptibility profiles and genotypes of 308 clinical and environmental isolates of Cryptococcus neoformans var. grubii and Cryptococcus gattii serotype B from north-western India

“…grubii and 60 (41 %) were C. gattii serotype B. They had been collected and stocked during our investigation of decayed wood inside trunk hollows of a wide spectrum of tree species and soil samples in proximity to some of the positive trees (Randhawa et al, 2006(Randhawa et al, , 2008Hiremath et al, 2008). Also included for comparison were eight reference strains procured from global culture collections.…”

“…grubii and C. gattii tested here were identified by standard mycological procedures (Randhawa et al, 2006(Randhawa et al, , 2008Hiremath et al, 2008). Their genotypes were determined based on two methods: (i) PCR fingerprinting using (GACA) 4 and M13 phage core sequences as single primers (Meyer et al, 1999); and (ii) DNA sequences at the URA5 locus (Meyer et al, 2009).…”

“…In India, we have reported a widespread colonization of decayed wood inside trunk hollows of diverse tree species by C. neoformans var. grubii and C. gattii serotype B (Randhawa et al, 2006(Randhawa et al, , 2008Hiremath et al, 2008). The objective of this study was to compare antifungal susceptibility profiles of clinical isolates with those of environmental isolates of C. neoformans var.…”