Yeast diversity sampling on the San Juan Islands reveals no evidence for the spread of the Vancouver IslandCryptococcus gattiioutbreak to this locale

Abstract

Biological diversity has been estimated for various phyla of life, such as insects and mammals, but in the microbe world is has been difficult to determine species richness and abundance. Here we describe a study of species diversity of fungi with a yeast-like colony morphology from the San Juan Islands, a group of islands that lies southeast of Vancouver Island, Canada. Our sampling revealed that the San Juan archipelago biosphere contains a diverse range of such fungi predominantly belonging to the Basidiomycota, particularly of the order Tremellales. One member of this group, Cryptococcus gattii, is the etiological agent of a current and ongoing outbreak of cryptococcosis on nearby Vancouver Island. Our sampling did not, however, reveal this species. While the lack of recovery of C. gattii does not preclude its presence on the San Juan Islands, our results suggest that the Strait of Juan de Fuca may be serving as a geographical barrier to restrict the dispersal of this primary human fungal pathogen into the United States.

Characterization of Environmental Sources of the Human and Animal Pathogen Cryptococcus gattii in British Columbia, Canada, and the Pacific Northwest of the United States

“…on March 22, 2019 by guest http://aem.asm.org/ 092B/06), which were sampled by another group (21). These results suggest that there are "hot spots" of C. gattii within the sampled areas.…”

“…It has been suggested that eucalyptus tree imports could be the route of introduction of C. gattii into the Pacific Northwest (20,21), particularly since one isolate (CBS7750) with a geno- (6,7,10,16,28,46,50,51). However, few of these studies have tested the hypotheses with genotypic data, and given the apparent global dispersal of C. gattii (31), it is difficult to demonstrate that C. gattii was absent from these areas prior to its isolation from imported trees.…”

“…gattii has also been isolated from eucalypts in California, Colombia, Argentina, Brazil, India, and Egypt (7,10,16,25,28,46,49,51), as well as Ficus soatensis, Croton bogotanus, Croton funckianus, Coussapoa sp., Cupressus lusitanica (Mexican cypress), Pinus radiata (Monterey pine), Acacia decurrens (black wattle), and Terminalia catappa (almond tree) in Colombia (5,25) and Moquilea tomentosa (pottery tree), Cassia grandis (pink shower tree), and an Amazonian "quina-quina" tree (Guettarda acreana) in Brazil (18,41). The presence of C. gattii outside of Australia has been speculatively attributed to the export of eucalypts from Australia in the form of seeds or cuttings (7,14,20,21,64). Environmental sampling for C. gattii in British Columbia from October 2001 to June 2002 was described previously (32).…”

Spread ofCryptococcus gattiiinto Pacific Northwest Region of the United States

“…gattii was consistently isolated from some areas. However, it was not found in the environment in other areas, such as the San Juan Islands ( 36 ), which suggests that environmental hot spots (zones of high concentration) of C . gattii may be found within the same broad ecologic niches.…”

The Fungus among Us: Cryptococcus neoformans and Cryptococcus gattii Ecological Modeling for Colombia

“…Furthermore, the recovery rate of Cryptococcus spp. may be very low, thereby requiring a large number of samples to be taken without any guarantee of success [13]. …”