Cryptococcus gattii Infection in an Immunocompetent Patient from Southern Italy

Global warming impact on the expansion of fundamental niche of Cryptococcus gattii VGI in Europe

In the present study, we analysed how geographical distribution of the fungal pathogen Cryptococcus gattii VGI in Europe and Mediterranean area has evolved in the last four decades based on the climatic changes, and we tried to predict the scenario for the next decade. Niche modelling by Maxent analysis showed that recent climate changes have significantly affected the distribution of the fungus revealing a gradual expansion of the fundamental niche from 1980 to 2009 followed by an impressive increase in the last decade (2010-2019) during which the environmental surface suitable for the fungal survival was more than doubled. In the next decade, our model predicted an increase in the area of distribution of C. gattii VGI from the coasts of the Mediterranean basin towards the more internal sub-continental areas. On the basis of these predictions, an increase of cases of cryptococcosis due to C. gattii VGI is expected in the next decade and a constant monitoring of the epidemiology of this fungal pathogen represents a crucial strategy to detect the onset of future outbreaks.

First report of cryptococcosis due to Cryptococcus gattii sensu stricto VGI in an Ivorian HIV negative patient

INTRODUCTION

Cryptococcus gattii species complex is endemic to tropical and subtropical regions and is described as a causative agent of cryptococcosis in immunocompetent individuals.

CASE PRESENTATION

We describe the first case of cryptococcosis in a HIV-negative patient from Ivory Coast infected by Cryptococcus gattii sensu stricto VGI. Isolates were recovered from cerebrospinal fluid (CSF) prior to systemic antifungal treatment up to 42 days after detection of the presence of yeasts in the CSF. Eighteen isolates were recovered, genetic diversity and antifungal susceptibility analyses were performed. All the isolates belonged to the Cryptococcus gattii sensu stricto (B;VGI) and were identified as a new sequence type (ST) 553 by Multilocus Sequence Typing (MLST) analyses. Susceptibility testing showed that all the strains had a wild-type phenotype for fluconazole, amphotericin B and flucytosine. Treatment with fluconazole (1200mg/day) was initiated with success.

CONCLUSION

This is the first case report of the presence of C. gattii sensu stricto VGI in a HIV-negative ivorian patient and the second report of the presence of species from the C. gattii complex species in this country.

Cryptococcosis caused by cryptococcus gattii: 2 case reports and literature review

Cryptococcosis caused by Cryptococcus gattii, is a life threatening fungal infection with recently increasing prevalence. C. gattii is a species complex comprising multiple independent species. However, many biological characteristics and clinical features of cryptococcosis due to C. gattii are relatively less well defined. In this paper, we identify two cases of C. gattii infection, and laboratory findings of genotype VGI and VGII in two groups of apparently immunocompetent Chinese individuals respectively. Upon detailed review of all 35 cases of C. gattii infections, it was observed that C. gattii can cause debilitating illness in both immunocompetent and immunocompromised individuals. Cryptococcosis due to C. gattii is a serious systemic fungal infection, with pulmonary central nervous system tropism. Epidemiologically, C. gattii infection is not only restricted in tropical and subtropical regions, but also in other geographical settings.

Molecular characterization of Cryptococcus neoformans and Cryptococcus gattii from environmental sources and genetic comparison with clinical isolates in Apulia, Italy

The present study investigated the environmental distribution of Cryptococcus neoformans and C. gattii species complex molecular types, mating types and sequence types in Apulia, a region of Southern Italy. A total of 2078 specimens from arboreal and animal sources were analyzed. The percentage of positive samples was similar among both arboreal and animal specimens: 4.2% vs. 5.1% for C. neoformans species complex and 0.6% vs. 1.4% for C. gattii species complex. Molecular typing identified 78 isolates as VNI (76 αA and two aA), one as AD-hybrid αADa, and 16 as VGI aB. VNI isolates presented 10 different sequence types (STs) and VGI isolates two. The most frequent STs among C. neoformans and C. gattii species complex isolates were ST23 (51%) and ST156 (90%), respectively. Comparison with molecular types and STs results obtained from 21 clinical isolates collected in Apulia showed that one C. neoformans VNI clinical isolate shared an identical sequence type of one arboreal isolate (ST61) and that one C. gattii VGI clinical isolate matched with the main ST (ST156) present in the environment. In addition, molecular type VNIV was found only among clinical isolates and was absent in the investigated environmental area. In conclusion, the present study identified which C. neoformans and C. gattii species complex genotypes are circulating in Apulia, defined their ecological niches and revealed the relationship with clinical cases. It represents a basal study for addressing future investigations and public health interventions in the region.

Environmental distribution of Cryptococcus neoformans and C. gattii around the Mediterranean basin

In order to elucidate the distribution of Cryptococcus neoformans and C. gattii in the Mediterranean basin, an extensive environmental survey was carried out during 2012-2015. A total of 302 sites located in 12 countries were sampled, 6436 samples from 3765 trees were collected and 5% of trees were found to be colonized by cryptococcal yeasts. Cryptococcus neoformans was isolated from 177 trees and C. gattii from 13. Cryptococcus neoformans colonized 27% of Ceratonia, 10% of Olea, Platanus and Prunus trees and a lower percentage of other tree genera. The 13 C. gattii isolates were collected from five Eucalyptus, four Ceratonia, two Pinus and two Olea trees. Cryptococcus neoformans was distributed all around the Mediterranean basin, whereas C. gattii was isolated in Greece, Southern Italy and Spain, in agreement with previous findings from both clinical and environmental sources. Among C. neoformans isolates, VNI was the prevalent molecular type but VNII, VNIV and VNIII hybrid strains were also isolated. With the exception of a single VGIV isolate, all C. gattii isolates were VGI. The results confirmed the presence of both Cryptococcus species in the Mediterranean environment, and showed that both carob and olive trees represent an important niche for these yeasts.

Cryptococcus neoformans in the respiratory tract of squirrels, Callosciurus finlaysonii (Rodentia, Sciuridae)

Cryptococcosis is a fungal disease acquired from the environment, for which animals may serve as sentinels for human exposure. The occurrence of Cryptococcus spp. in the respiratory tract of 125 squirrels, Callosciurus finlaysonii, trapped in Southern Italy, was assessed. Upon examination of nasal swabs and lung tissue from each individual, a total of 13 (10.4%) animals scored positive for yeasts, 7 for Cryptococcus neoformans (C.n.) (5.6%) and 6 for other yeasts (4.8%). C.n. was isolated from the nostrils and lungs, with a high population size in nostrils. Two C.n. molecular types, VNI and VNIV, were identified, with C.n. var. grubii VNI the most prevalent. Phylogenetic analyses of ITS+ and URA5 sequences revealed that C.n. isolates were genetically similar to isolates from a range of geographical areas and hosts. Results suggest that C.n. can colonize or infect the respiratory tract of C. finlaysonii. The high occurrence and level of colonization of nasal cavities might be an indicator of environmental exposure to high levels of airborne microorganism. The close phylogenetic relationship of C.n. strains from squirrels with those from human and other animal hosts suggests a potential role for these animals as "sentinels" for human exposure.

Cryptococcus gattii infections

Understanding of the taxonomy and phylogeny of Cryptococcus gattii has been advanced by modern molecular techniques. C. gattii probably diverged from Cryptococcus neoformans between 16 million and 160 million years ago, depending on the dating methods applied, and maintains diversity by recombining in nature. South America is the likely source of the virulent C. gattii VGII molecular types that have emerged in North America. C. gattii shares major virulence determinants with C. neoformans, although genomic and transcriptomic studies revealed that despite similar genomes, the VGIIa and VGIIb subtypes employ very different transcriptional circuits and manifest differences in virulence phenotypes. Preliminary evidence suggests that C. gattii VGII causes severe lung disease and death without dissemination, whereas C. neoformans disseminates readily to the central nervous system (CNS) and causes death from meningoencephalitis. Overall, currently available data indicate that the C. gattii VGI, VGII, and VGIII molecular types more commonly affect nonimmunocompromised hosts, in contrast to VGIV. New, rapid, cheap diagnostic tests and imaging modalities are assisting early diagnosis and enabling better outcomes of cerebral cryptococcosis. Complications of CNS infection include increased intracranial pressure, severe neurological sequelae, and development of immune reconstitution syndrome, although the mortality rate is low. C. gattii VGII isolates may exhibit higher fluconazole MICs than other genotypes. Optimal therapeutic regimens are yet to be determined; in most cases, initial therapy with amphotericin B and 5-flucytosine is recommended.

Retrospective study of the epidemiology and clinical manifestations of Cryptococcus gattii infections in Colombia from 1997-2011

BACKGROUND

Cryptococcosis due to Cryptococcus gattii is endemic in various parts of the world, affecting mostly immunocompetent patients. A national surveillance study of cryptococcosis, including demographical, clinical and microbiological data, has been ongoing since 1997 in Colombia, to provide insights into the epidemiology of this mycosis.

METHODOLOGY/PRINCIPAL FINDINGS

From 1,209 surveys analyzed between 1997-2011, 45 cases caused by C. gattii were reported (prevalence 3.7%; annual incidence 0.07 cases/million inhabitants/year). Norte de Santander had the highest incidence (0.81 cases/million/year), representing 33.3% of all cases. The male: female ratio was 3.3∶1. Mean age at diagnosis was 41±16 years. No specific risk factors were identified in 91.1% of patients. HIV infection was reported in 6.7% of patients, autoimmune disease and steroids use in 2.2%. Clinical features included headache (80.5%), nausea/vomiting (56.1%) and neurological derangements (48.8%). Chest radiographs were taken in 21 (46.7%) cases, with abnormal findings in 7 (33.3%). Cranial CT scans were obtained in 15 (33.3%) cases, with abnormalities detected in 10 (66.7%). Treatment was well documented in 30 cases, with most receiving amphotericin B. Direct sample examination was positive in 97.7% cases. Antigen detection was positive for all CSF specimens and for 75% of serum samples. C. gattii was recovered from CSF (93.3%) and respiratory specimens (6.6%). Serotype was determined in 42 isolates; 36 isolates were serotype B (85.7%), while 6 were C (14.3%). The breakdowns of molecular types were VGII (55.6%), VGIII (31.1%) and VGI (13.3%). Among 44 strains, 16 MLST sequence types (ST) were identified, 11 of them newly reported.

CONCLUSIONS/SIGNIFICANCE

The results of this passive surveillance study demonstrate that cryptococcosis caused by C. gattii has a low prevalence in Colombia, with the exception of Norte de Santander. The predominance of molecular type VGII is of concern considering its association with high virulence and the potential to evolve into outbreaks.

Primary cutaneous cryptococcosis in an immunocompetent patient due to Cryptococcus gattii molecular type VGI in Brazil: a case report and review of literature

Primary Cutaneous Cryptococcosis is an uncommon infection caused by the yeast Cryptococcus neoformans and C. gattii. Few case reports are available in the literature describing in detail primary cutaneous cryptococcosis due to C. gattii in immunocompetent patients. Herein, we present a case of a 68-year-old immunocompetent male patient with erythematous nodular lesions on the right forearm due to C. gattii mating-type α and molecular type VGI. The virulence factors test was performed for capsule diameter, melanin production and phospholipase activity. In vitro fluconazole testing showed the sensitivity profile of this clinical isolate. In addition, a review of the literature on this subject was carried out and verified that this is the first reported case of VGI in the south-east region of Brazil.

Development of an aerosol model of Cryptococcus reveals humidity as an important factor affecting the viability of Cryptococcus during aerosolization

Cryptococcus is an emerging global health threat that is annually responsible for over 1,000,000 infections and one third of all AIDS patient deaths. There is an ongoing outbreak of cryptococcosis in the western United States and Canada. Cryptococcosis is a disease resulting from the inhalation of the infectious propagules from the environment. The current and most frequently used animal infection models initiate infection via liquid suspension through intranasal instillation or intravenous injection. These models do not replicate the typically dry nature of aerosol exposure and may hinder our ability to decipher the initial events that lead to clearance or the establishment of infection. We have established a standardized aerosol model of murine infection for the human fungal pathogen Cryptococcus. Aerosolized cells were generated utilizing a Collison nebulizer in a whole-body Madison Chamber at different humidity conditions. The aerosols inside the chamber were sampled using a BioSampler to determine viable aerosol concentration and spray factor (ratio of viable aerosol concentration to total inoculum concentration). We have effectively delivered yeast and yeast-spore mixtures to the lungs of mice and observed the establishment of disease. We observed that growth conditions prior to exposure and humidity within the Madison Chamber during exposure can alter Cryptococcus survival and dose retained in mice.

Autochthonous and dormant Cryptococcus gattii infections in Europe

Until recently, Cryptococcus gattii infections occurred mainly in tropical and subtropical climate zones. However, during the past decade, C. gattii infections in humans and animals in Europe have increased. To determine whether the infections in Europe were acquired from an autochthonous source or associated with travel, we used multilocus sequence typing to compare 100 isolates from Europe (57 from 40 human patients, 22 from the environment, and 21 from animals) with 191 isolates from around the world. Of the 57 human patient isolates, 47 (83%) were obtained since 1995. Among the 40 patients, 24 (60%) probably acquired the C. gattii infection outside Europe; the remaining 16 (40%) probably acquired the infection within Europe. Human patient isolates from Mediterranean Europe clustered into a distinct genotype with animal and environmental isolates. These results indicate that reactivation of dormant C. gattii infections can occur many years after the infectious agent was acquired elsewhere.

Molecular epidemiology of Italian clinical Cryptococcus neoformans var. grubii isolates

Cryptococcus neoformans variety grubii is the major etiological agent of cryptococcal meningitis in both immunocompromised and immunocompetent patients. The current PCR-based molecular methods are not sufficient to discriminate among the different populations of this yeast. Therefore, the aim of the present study was to investigate the genotypes of the Italian clinical C. neoformans var. grubii isolates by multilocus sequence typing (MLST). A total of 53 isolates, each representative of a single case, were studied. Genotyping was performed using the ISHAM Cryptococcus MLST consensus scheme and the results were compared to the publically available global C. neoformans var. grubii MLST dataset. A total of 16 genotypes were identified; 14 were new genotypes, one was identical to sequence type (ST) ST81, which had been previously reported from Thailand, and one to ST23 already identified in Uganda, the USA and Korea. Sequence type ST61 was the most numerous, including 16 isolates. Network phylogenetic analysis showed that the Italian isolates could be divided into at least three clusters with similarities with those recovered in Africa, Asia and Americas. Distribution of the STs among the isolates could not be correlated to the hospital in which they were recovered or to the HIV status of the patients. The majority of the isolates belonged to the molecular type VNI; three belonged to the rare molecular type VNII and one to the VNB group, which until now had not been described in Europe. The results reveal that the Italian C. neoformans var. grubii population presents a distinct variability, displaying a high number of new genotypes, and probably recombines sexually.

Global Molecular Epidemiology of Cryptococcus neoformans and Cryptococcus gattii: An Atlas of the Molecular Types

Cryptococcosis is a fungal disease affecting more than one million people per year worldwide. The main etiological agents of cryptococcosis are the two sibling species Cryptococcus neoformans and Cryptococcus gattii that present numerous differences in geographical distribution, ecological niches, epidemiology, pathobiology, clinical presentation and molecular characters. Genotyping of the two Cryptococcus species at subspecies level supplies relevant information to understand how this fungus has spread worldwide, the nature of its population structure, and how it evolved to be a deadly pathogen. At present, nine major molecular types have been recognized: VNI, VNII, VNB, VNIII, and VNIV among C. neoformans isolates, and VGI, VGII, VGIII, and VGIV among C. gattii isolates. In this paper all the information available in the literature concerning the isolation of the two Cryptococcus species has been collected and analyzed on the basis of their geographical origin, source of isolation, level of identification, species, and molecular type. A detailed analysis of the geographical distribution of the major molecular types in each continent has been described and represented on thematic maps. This study represents a useful tool to start new epidemiological surveys on the basis of the present knowledge.

Cryptococcus gattii as an important fungal pathogen of western North America

Cryptococcus gattii, a pathogenic fungus historically appreciated to be endemic to tropical regions, was recognized to emerge in a more temperate zone of North America in the 1990s. Early reports focused on an outbreak that was first apparent on Vancouver Island (BC, Canada), involving both the veterinary and human population. More recently, it has been recognized that this organism is endemic to a wider geography in western North America, with recognized disease caused by unique molecular subtypes in both healthy and immunosuppressed human hosts and a variety of domestic and wild animals. A number of cases of disease caused by C. gattii isolates that are unrelated to the Vancouver Island-Pacific Northwest outbreak strains have also been recognized in different parts of the USA. As microbiology laboratories have historically not identified these organisms to the species level, our current understanding of the scope of this infection is probably an underestimate. Ongoing public health epidemiologic efforts will be facilitated by increased attention towards culture-confirmed diagnosis and species identification in clinical microbiology laboratories. Early experience presents a strong rationale for increasing diagnostic attention, with multiple clinical features that are unique to this infection, including variability in antifungal susceptibilities and a heightened need for aggressive management of inflammatory responses. Larger prospective studies to evaluate and optimize clinical management are needed.

Cryptococcus gattii, no longer an accidental pathogen?

Cryptococcus gattii is an environmentally occurring pathogen that is responsible for causing cryptococcosis marked by pneumonia and meningoencephalitis in humans and animals. C. gattii can form long-term associations with trees and soil resulting in the production of infectious propagules (spores and desiccated yeast). The ever expanding reports of clinical and environmental isolation of C. gattii in temperate climates strongly imply C. gattii occurs world-wide. The key ability of yeast and spores to enter, survive, multiply, and exit host cells and to infect immunocompetent hosts distinguishes C. gattii as a primary pathogen and suggest evolution of C. gattii pathogenesis as a result of interaction with plants and other organisms in its environmental niche. Here we summarize the historical literature on C. gattii and recent literature supporting the world-wide occurrence of the primary pathogen C. gattii.