Dating the Cryptococcus gattii Dispersal to the North American Pacific Northwest.

The emergence of Cryptococcus gattii, previously regarded as a predominantly tropical pathogen, in the temperate climate of the North American Pacific Northwest (PNW) in 1999 prompted several questions. The most prevalent among these was the timing of the introduction of this pathogen to this novel environment. Here, we infer tip-dated timing estimates for the three clonal C. gattii populations observed in the PNW, VGIIa, VGIIb, and VGIIc, based on whole-genome sequencing of 134 C. gattii isolates and using Bayesian evolutionary analysis by sampling trees (BEAST). We estimated the nucleotide substitution rate for each lineage (1.59 × 10-8, 1.59 × 10-8, and 2.70 × 10-8, respectively) to be an order of magnitude higher than common neutral fungal mutation rates (2.0 × 10-9), indicating a microevolutionary rate (e.g., successive clonal generations in a laboratory) in comparison to a species' slower, macroevolutionary rate (e.g., when using fossil records). The clonal nature of the PNW C. gattii emergence over a narrow number of years would therefore possibly explain our higher mutation rates. Our results suggest that the mean time to most recent common ancestor for all three sublineages occurred within the last 60 to 100 years. While the cause of C. gattii dispersal to the PNW is still unclear, our research estimates that the arrival is neither ancient nor very recent (i.e., <25 years ago), making a strong case for an anthropogenic introduction. IMPORTANCE The recent emergence of the pathogenic fungus Cryptococcus gattii in the Pacific Northwest (PNW) resulted in numerous investigations into the epidemiological and enzootic impacts, as well as multiple genomic explorations of the three primary molecular subtypes of the fungus that were discovered. These studies lead to the general conclusion that the subtypes identified likely emerged out of Brazil. Here, we conducted genomic dating analyses to determine the ages of the various lineages seen in the PNW and propose hypothetical causes for the dispersal events. Bayesian evolutionary analysis strongly suggests that these independent fungal populations in the PNW are all 60 to 100 years old, providing a timing that is subsequent to the opening of the Panama Canal, which allowed for more direct shipping between Brazil and the western North American coastline, a possible driving event for these fungal translocation events

Susceptibility of Cryptococcus neoformans and Cryptococcus gattii from clinical and environment sources in Nairobi, Kenya

Objective: To determine anti-fungal susceptibility of Cryptococcus neoformans andCryptococcus gattii from environmental and clinical sources in Nairobi, Kenya.Design: Prospective study.Setting: Kenya Medical Research Institute, Mycology laboratory, Nairobi, Kenya.Subjects: A total of 123 isolates were tested for their susceptibility to fluconazole(FLC), amphotericin B(AMP) and fluorocytosine (5FC). Clinical isolates were 70(66Cryptococcus neoformans and 4 Cryptococcus gattii) while environmental isolates were53(41 C. neoformans and 12 C. gattii). The isolates were characterised using variousphenotypic tests including microscopic morphology, physiological and biochemicaltests (API 20 Caux), pigmentation on bird seed agar and reaction on canavanineglycine-bromthymolblue agar. European Committee on Anti-microbial SusceptibilityStandards (EUCAST) was used as the reference method for susceptibility testing.Results: Most C. neoformans isolates; clinical (61/66; 92.4%) and environmental (38/41;92.7%) were susceptible to FLC. The number of C. neoformans isolates inhibited atsusceptible dose dependent (SDD) range (16-32μg/ml) by FLC were clinical (4/66; 6.1%)and environmental (2/41; 4.9%). One C. neoformans isolate each; clinical (1/66; 1.5%)and environmental (1/41; 2.4%) was resistant to FLC. All C. gatti isolates from clinicaland environmental were fully susceptible to FLC. The percentage of C. neoformansisolates that were susceptible (S) (MIC ≤ 1.0 μg/ml) to AMP were; clinical(52/66; 90.2%)and environmental (37/41; 78.8%) while the rest were susceptible dose dependent(SDD) with MIC (2-8μg/ml). Reduced susceptibilities to 5FC was displayed in allclinical and environmental C. neoformans and C. gatii isolates; for instance resistanceto 5FC was reported in C. neoformans; clinical (8/66; 12.1%) and environmental (1/41;2.4 %). Among the C. gattii isolates there was also decreased susceptibility to 5FCwith Minimum Inhibition Concentration (MIC) range of between 0.5-32 μg/ml. Therewere no significant differences in susceptibility ranges among all the clinical andenvironmental isolates.Conclusion: This study demonstrated reduced susceptibilities among C. neoformansand C. gattii isolates to commonly used anti-fungal drugs

Cryptococcosis by Cryptococcus gattii in immunocompetent goats in Spain and review of the literature

Cryptococcus neoformans  has been described for years as a species causing spontaneous mycosis in a great variety of animals. The new species C. gattii has been described as an agent of animal cryptococcosis mainly in Australia, but it has been found also in many parts of the world. The main group of animals suffering those natural infections are mammals, but also birds, reptiles and some invertebrates have suffered cryptococcosis. Usually the infections are sporadic and occasional, but some epidemic outbreaks have been reported affecting a high number of animals. In 1998 the isolation of C. gattii was reported by the first time in Europe in 5 epidemic outbreaks of cryptococcosis in goats grazing freely in west Spain grasslands. In all outbreaks, mycological studies were possible from samples obtained on necropsy of some animals dead during the epidemic. Animals belonged to various milking breeds and were grazing with variable status of health and husbandry. Goats affected by cryptococcosis showed similar respiratory symptoms, consisting in mucopurulent nasal discharge, cough, dyspnea and progressive cachexia, causing death in a period of 2 to 4 weeks. In three outbreaks many animals also showed ataxia, midriasis, blindness and progressive paralysis. Clinical prevalence varied from 2 to 12% in the different outbreaks. It is evident that in spite of the great amplitude of geographical distribution observed for C. gattii, this species has a limited presence, possibly restricted to determined habitats, as that of infection of goats flocks in Spain. Veterinarians must be concerned about Cryptococcosis in grazing animals. This finding introduced new elements connected to the epidemiology and ecology of Cryptococcus gattii

Clonal dispersal of Cryptococcus gattii VGII in an endemic region of cryptococcosis in Colombia

This study characterized the genotype and phenotype of Cryptococcus gattii VGII isolates from Cucuta, an endemic region of cryptococcal disease in Colombia, and compared these traits with those from representative isolates from the Vancouver Island outbreak (VGIIa and VGIIb). Genetic diversity was assessed by multilocus sequence typing (MLST) analysis. Phenotypic characteristics, including growth capacity under different temperature and humidity conditions, macroscopic and microscopic morphology, phenotypic switching, mating type, and activity of extracellular enzymes were studied. Virulence was studied in vivo in a mouse model. MLST analysis showed that the isolates from Cucuta were highly clonal, with ST25 being the most common genotype. Phenotypically, isolates from Cucuta showed large cell and capsular sizes, and shared phenotypic traits and enzymatic activities among them. The mating type a prevailed among the isolates, which were fertile and of considerable virulence in the animal model. This study highlights the need for a continuous surveillance of C. gattii in Colombia, especially in endemic areas like Cucuta, where the highest number of cryptococcosis cases due to this species is reported. This will allow the early detection of potentially highly virulent strains that spread clonally, and can help prevent the occurrence of outbreaks in Colombia and elsewhere. © 2019 by the authors

The Cryptococcus gattii species complex:Unique pathogenic yeasts with understudied virulence mechanisms

Members of Cryptococcus gattii/neoformans species complex are the etiological agents of the potentially fatal human fungal infection cryptococcosis. C. gattii and its sister species cause disease in both immunocompetent and immunocompromised hosts, while the closely related species C. neoformans and C. deneoformans predominantly infect immunocompromised hosts. To date, most studies have focused on similarities in pathogenesis between these two groups, but over recent years, important differences have become apparent. In this review paper, we highlight some of the major phenotypic differences between the C. gattii and neoformans species complexes and justify the need to study the virulence and pathogenicity of the C. gattii species complex as a distinct cryptococcal group.</p

Genome Variation in Cryptococcus gattii, an Emerging Pathogen of Immunocompetent Hosts

Cryptococcus gattii recently emerged as the causative agent of cryptococcosis in healthy individuals in western North America, despite previous characterization of the fungus as a pathogen in tropical or subtropical regions. As a foundation to study the genetics of virulence in this pathogen, we sequenced the genomes of a strain (WM276) representing the predominant global molecular type (VGI) and a clinical strain (R265) of the major genotype (VGIIa) causing disease in North America. We compared these C. gattii genomes with each other and with the genomes of representative strains of the two varieties of Cryptococcus neoformans that generally cause disease in immunocompromised people. Our comparisons included chromosome alignments, analysis of gene content and gene family evolution, and comparative genome hybridization (CGH). These studies revealed that the genomes of the two representative C. gattii strains (genotypes VGI and VGIIa) are colinear for the majority of chromosomes, with some minor rearrangements. However, multiortholog phylogenetic analysis and an evaluation of gene/sequence conservation support the existence of speciation within the C. gattii complex. More extensive chromosome rearrangements were observed upon comparison of the C. gattii and the C. neoformans genomes. Finally, CGH revealed considerable variation in clinical and environmental isolates as well as changes in chromosome copy numbers in C. gattii isolates displaying fluconazole heteroresistance

Criptococose cutânea causada por Cryptococcus gattii em um paciente sob corticoterapia crônica

Cryptococcus gattii é agente causador de uma micose endêmica que afeta principalmente os pulmões e o sistema nervoso central de pacientes imunocompetentes em regiões tropicais e subtropicais do globo. Relato de caso. Um paciente de 66 anos, portador de doença pulmonar obstrutiva crônica, não infectado pelo vírus HIV, em corticoterapia sistêmica prolongada, desenvolveu extensa ulceração do antebraço esquerdo, associada a adenomegalia supraclavicular ipsilateral, em conseqüência à infecção por Cryptococcus gattii. O paciente foi tratado com fluconazol 400mg/dia durante 8 meses, obtendo resolução completa da lesão. Este caso enfatiza que, ainda que raramente, C. gattii pode causar infecção cutâneo-linfática oportunista, em paciente imunocomprometido pelo uso sistêmico de corticosteróides vivendo na região sudeste do Brasil.Cryptococcus gattii causes a form of endemic mycosis that most commonly affects the lungs and central nervous system of immunocompetent patients living in tropical and subtropical areas of the world. Case report. A 66-year-old man who had chronic obstructive pulmonary disease without HIV infection and had been on systemic corticotherapy for several years developed extensive ulceration of the left forearm that was associated with ipsilateral supraclavicular adenomegaly, consequent to infection with Cryptococcus gattii. The patient was treated with fluconazole 400mg/day for eight months, which led to complete healing of the lesion. This case emphasizes that, although rare, C. gattii may cause opportunistic cutaneous-lymphatic infection in patients living in the southeastern region of Brazil who are immunocompromised through chronic corticotherapy

Cryptococcus gattii infection in an immunocompetent host in Greece

We report a case of a 31-year-old otherwise healthy female with pulmonary cryptococcoma along with cryptococcal meningitis due to Cryptococcus gattii molecular type VGI, in Greece. Combined antifungal treatment and surgical excision of pulmonary cryptococcoma yielded a good response

Pathogenic diversity amongst serotype C VGIII and VGIV Cryptococcus gattii isolates

Cryptococcus gattii is one of the causative agents of human cryptococcosis. Highly virulent strains of serotype B C. gattii have been studied in detail, but little information is available on the pathogenic properties of serotype C isolates. In this study, we analyzed pathogenic determinants in three serotype C C. gattii isolates (106.97, ATCC 24066 and WM 779). Isolate ATCC 24066 (molecular type VGIII) differed from isolates WM 779 and 106.97 (both VGIV) in capsule dimensions, expression of CAP genes, chitooligomer distribution, and induction of host chitinase activity. Isolate WM 779 was more efficient than the others in producing pigments and all three isolates had distinct patterns of reactivity with antibodies to glucuronoxylomannan. This great phenotypic diversity reflected in differential pathogenicity. VGIV isolates WM 779 and 106.97 were similar in their ability to cause lethality and produced higher pulmonary fungal burden in a murine model of cryptococcosis, while isolate ATCC 24066 (VGIII) was unable to reach the brain and caused reduced lethality in intranasally infected mice. These results demonstrate a high diversity in the pathogenic potential of isolates of C. gattii belonging to the molecular types VGIII and VGIV