A rare genotype of Cryptococcus gattii caused the cryptococcosis outbreak on Vancouver Island (British Columbia, Canada)

Abstract

Cryptococcus gattii causes life-threatening infection of the pulmonary and central nervous systems in hosts with normal immunity and traditionally has been considered to be restricted geographically to tropical and subtropical climates. The recent outbreak of C. gattii in the temperate climate of Vancouver Island, BC, Canada, led to a collaborative investigation. The objectives of the current study were to ascertain the environmental source of the outbreak infections, survey the molecular types of the outbreak and environmental cryptococcal isolates, and determine the extent of genetic diversity among the isolates. PCR-fingerprinting and amplified fragment length polymorphism (AFLP) were used to examine the genotypes, and mating assays were performed to determine the mating type of the isolates. All outbreak and environmental isolates belonged to C. gattii. Concordant results were obtained by using PCR-fingerprinting and AFLP analysis. The vast majority of clinical and veterinary infections were caused by isolates of the molecular type VGII͞AFLP6, but two were caused by molecular type VGI͞AFLP4. All environmental isolates belonged to molecular type VGII͞AFLP6. Two or three subtypes were observed within VGII͞AFLP6 among outbreak and environmental isolates. All mating-competent isolates were of the ␣-mating type. The emergence of this usually tropical pathogen on Vancouver Island highlights the changing distribution of this genotype and emphasizes the importance of an ongoing collaborative effort to monitor the global epidemiology of this yeast.PCR fingerprinting ͉ amplified fragment length polymorphism (AFLP) ͉ restriction fragment length polymorphism (RFLP) ͉ mating type

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).…”

Phenotypic Switching of Cryptococcus neoformans and Cryptococcus gattii

“…grubii, however, have not been documented. C. gattii (serotypes B and C) was originally predominantly found in subtropical regions but a newly recombined serotype B clone has emerged over the past 10 years as a cause of cryptococcal infections in animals and otherwise healthy humans on Vancouver Island [17]. More recently, this epidemic is spreading to the Pacific Northwest of the United States [18,19].…”

Determinación in vitro de la pareja sexual en aislamientos del complejo Cryptococcus neoformans

“…It is interesting to observe that the mating process occurred in isolates of both mating types in a similar ratio, 9:6 (α:a), taking into account that it had been reported, that the α mating type strains occur in over 90% of the worldwide C. neoformans clinical and environmental isolates (14,24). However, it was recently reported by our group that 96.6% of serotype B isolates are of mating type a (17).…”

“…The mating type locus has been associated with virulence, as suggested by Kwon-Chung et al (13), who found that MATα strains were more virulent in a mouse model than the MAT a isolates. Recently it was found that the cryptococcosis outbreak on Vancouver Island, Canada was caused by isolates that were highly virulent mating type α strains belonging to the C. gattii molecular type VGII/AFLP6 (14,15).…”

“…The ability of C. neoformans strains to mate is determined by crossing the isolates with appropriate tester strains on nutrient starvation media (1,14,16). The tester strains (usually JEC 20, serotype D, mating type a, and JEC21, serotype D, mating type α) are mixed with the strains to be tested on a special media like V8 agar, SYB (sucrose, biotin, yeast extract) (19).…”