Molecular typing of global isolates of Cryptococcus neoformans var. neoformans by polymerase chain reaction fingerprinting and randomly amplified polymorphic DNA-a pilot study to standardize techniques on which to base a detailed epidemiological survey

Molecular epidemiological investigation of Cryptococcus spp. carried by captive koalas (Phascolarctos cinereus) in Japan

Cryptococcus neoformans and Cryptococcus gattii cause cryptococcosis, a systemic mycosis that infects a wide range of species. Recent molecular biological investigations have allowed for the genotyping of these species, providing more detailed information on their pathogenicity and infection routes. Koalas (Phascolarctos cinereus) are frequently colonized by Cryptococcus spp., but molecular epidemiological studies have yet to be conducted in Japan. Here, we conducted multi-locus sequence typing (MLST) analysis on Cryptococcus spp. colonization isolates obtained from all koalas kept in seven parks across Japan. Out of 46 koalas examined, 10 (22%) were positive for C. gattii and 3 (6.5%) were positive for C. neoformans. All C. gattii isolates belonged to molecular type VGI and were either sequence type (ST) 51 or a novel ST, and all C. neoformans isolates belonged to molecular type VNI and ST23. Despite the frequent movement of koalas between parks, the STs were relatively park-specific, suggesting that the floor of the rearing barns is a source of infection and may act as a reservoir. MLST analysis confirmed that C. gattii was transported, established, and spread by koalas in areas where C. gattii was not originally present. MLST analysis is considered useful in assessing the pathogenicity and tracing the transmission routes of Cryptococcus spp. carried by koalas.IMPORTANCEThis is the first study to conduct a multi-locus sequence typing analysis on Cryptococcus spp. carried by captive koalas in Japan. Cryptococcosis remains a globally high-fatality fungal infection in humans, and captive koalas are known to carry a high percentage of Cryptococcus spp. Through this research, the molecular types and transmission routes of Cryptococcus spp. carried by koalas have been elucidated, revealing the potential role of enclosure flooring as a reservoir. It has been confirmed that Cryptococcus gattii, which is not endemic in Japan, has become established through koalas and is spreading to new individuals in Japan. This study is believed to provide valuable insights into koala conservation and contribute to the One Health approach for Cryptococcosis, a zoonotic infection.

Determining Potential Link between Environmental and Clinical Isolates of Cryptococcus neoformans/Cryptococcus gattii Species Complexes Using Phenotypic and Genotypic Characterisation

Opportunistic infections due to Cryptococcus neoformans and C. gattii species complexes continue to rise unabated among HIV/AIDS patients, despite improved antifungal therapies. Here, we collected a total of 20 environmental and 25 presumptive clinical cryptococcal isolates from cerebrospinal fluid (CSF) samples of 175 patients enrolled in an ongoing clinical trial Ambition 1 Project (Botswana-Harvard Partnership). Identity confirmation of the isolates was done using MALDI-TOF MS and PCR. We describe the diversity of the isolates by PCR fingerprinting and sequencing (Oxford Nanopore Technology) of the intergenic spacer region. Mating types of the isolates were determined by amplification of the MAT locus. We report an unusual prevalence of 42.1% of C. neoformans x C. deneoformans hybrids Serotype AD (n = 16), followed by 39.5% of C. neoformans Serotype A (n = 15), 5.3% of C. deneoformans, Serotype D (n = 2), 7.9% of C. gattii (n = 3), and 5.3% of C. tetragattii (n = 2) in 38 representative isolates that have been characterized. Mating type-specific PCR performed on 38 representative environmental and clinical isolates revealed that 16 (42.1%) were MATa/MATα hybrids, 17 (44.7%) were MATα, and five (13.2%) possessed MATa mating type. We used conventional and NGS platforms to demonstrate a potential link between environmental and clinical isolates and lay a foundation to further describe mating patterns/history in Botswana.

The Predominance of a Specific Genotype of Cryptococcus neoformans var. Grubii in China and Japan

Background

The extensive deployment of molecular genotyping methods is the top reliable keyword to characterize the population genetic structure of C. neoformans in the past decade. However, studies involving genotypic analysis of C. neoformans var. grubii from China and Japan are limited.

Objectives

We address this challenge to determine the genotype distribution of C. neoformans var. grubii strains from China and Japan.

Methods

Genotypic analysis of 52 C. neoformans var. grubii isolates was performed using multilocus microsatellite typing (MLMT) based on the sequence analysis of 3 functional genes. In order to place the herein-studied strains into the global picture, 22 strains randomly selected from the 52 strains studied by MLMT were also analyzed by restriction fragment length polymorphism analysis of the orotidine monophosphate pyrophosphorylase gene (URA5-RFLP), M13 PCR-fingerprinting, and multilocus sequence typing (MLST).

Results

MLMT classified 46 (88.5%) of the 52 strains as genotype MLMT-17. The high prevalence of the MLMT-17 type was observed for environmental and clinical isolates from China and Japan. URA5-RFLP analysis, M13 PCR-fingerprinting, and MLST showed that most of these belong to the VNI/ST5 (M5) genotype.

Conclusions

Our study suggests the predominance of a specific genotype of C. neoformans var. grubii in China and Japan.

Cryptococcus: History, Epidemiology and Immune Evasion

Cryptococcosis is a disease caused by the pathogenic fungi Cryptococcus neoformans and Cryptococcus gattii, both environmental fungi that cause severe pneumonia and may even lead to cryptococcal meningoencephalitis. Although C. neoformans affects more fragile individuals, such as immunocompromised hosts through opportunistic infections, C. gattii causes a serious indiscriminate primary infection in immunocompetent individuals. Typically seen in tropical and subtropical environments, C. gattii has increased its endemic area over recent years, largely due to climatic factors that favor contagion in warmer climates. It is important to point out that not only C. gattii, but the Cryptococcus species complex produces a polysaccharidic capsule with immunomodulatory properties, enabling the pathogenic species of Cryptococccus to subvert the host immune response during the establishment of cryptococcosis, facilitating its dissemination in the infected organism. C. gattii causes a more severe and difficult-to-treat infection, with few antifungals eliciting an effective response during chronic treatment. Much of the immunopathology of this cryptococcosis is still poorly understood, with most studies focusing on cryptococcosis caused by the species C. neoformans. C. gattii became more important in the epidemiological scenario with the outbreaks in the Pacific Northwest of the United States, which resulted in phylogenetic studies of the virulent variant responsible for the severe infection in the region. Since then, the study of cryptococcosis caused by C. gattii has helped researchers understand the immunopathological aspects of different variants of this pathogen.

High genetic variability of clinical and environmental Cryptococcus gattii isolates from Brazil

Among Cryptococcus gattii genotypes, VGII has gained pivotal relevance in epidemiological, clinical and genetic contexts due to its association with several outbreaks in temperate regions and due to the high variability of this genotype. The aim of this study was to compare 25 isolates of C. gattii from the Southeast region of Brazil with previously described isolates from other regions of the country and around the world. Among the 25 isolates, 24 were VGII and one was VGI. All of them were newly identified. Three new allele types (AT) (AT47 for the URA5 locus, AT56 for the LAC1 locus, and AT96 for the IGS1 region) were also described. Compared with other Brazilian isolates, those from the Southeast region presented the greatest haplotype diversity. In general, the regions presented different sequence types (STs), and only nine STs were found in more than one location. GoeBURST analysis showed two large groups among the Brazilian isolates. The largest group consists of 59 STs predominantly from the North and Northeast regions; the other large group includes 57 STs from the Southeast and Midwest regions. In a global context the South American isolates presented the highest genetic diversity (STs = 145, haplotype diversity (Hd) = 0.999 and π = 0.00464), while the African populations showed the lowest genetic diversity (STs = 3, Hd = 0.667 and π = 0.00225). These results confirm that the Brazilian C. gattii VGII population is highly diverse and reinforce the hypothesis of dispersion of this genotype from South America.

Molecular Markers Reveal Epidemiological Patterns and Evolutionary Histories of the Human Pathogenic Cryptococcus

The human pathogenic Cryptococcus species are the main agents of fungal meningitis in humans and the causes of other diseases collectively called cryptococcosis. There are at least eight evolutionary divergent lineages among these agents, with different lineages showing different geographic and/or ecological distributions. In this review, we describe the main strain typing methods that have been used to analyze the human pathogenic Cryptococcus and discuss how molecular markers derived from the various strain typing methods have impacted our understanding of not only cryptococcal epidemiology but also its evolutionary histories. These methods include serotyping, multilocus enzyme electrophoresis, electrophoretic karyotyping, random amplified polymorphic DNA, restriction fragment length polymorphism, PCR-fingerprinting, amplified fragment length polymorphism, multilocus microsatellite typing, single locus and multilocus sequence typing, matrix-assisted laser desorption/ionization time of flight mass spectrometry, and whole genome sequencing. The major findings and the advantages and disadvantages of each method are discussed. Together, while controversies remain, these strain typing methods have helped reveal (i) the broad phylogenetic pattern among these agents, (ii) the centers of origins for several lineages and their dispersal patterns, (iii) the distributions of genetic variation among geographic regions and ecological niches, (iv) recent hybridization among several lineages, and (v) specific mutations during infections within individual patients. However, significant challenges remain. Multilocus sequence typing and whole genome sequencing are emerging as the gold standards for continued strain typing and epidemiological investigations of cryptococcosis.

Isolation, molecular identification, and phylogenetic evaluation of Cryptococcus neoformans isolated from pigeon lofts, Psittaciformes, and Passeriformes in Ahvaz, Iran

Cryptococcus neoformans, the main pathogen in immunocompromised patients, is a ubiquitous free-living fungus that can be isolated from avian excreta, soils, and plant material. This study was carried out to determine the infection rate of pigeon lofts, Passeriformes, and Psittaciformes in Ahvaz, the capital of Khuzestan province in Iran and to determine varieties of Cryptococcus neoformans (C. neoformans). The 80 samples were collected from pigeon lofts. Also, 163 feces of captive birds (Passeriformes and Psittaciformes) which kept in Ahvaz pet shops, and the 70 cloacal swabs of pet birds (Passeriformes and psittaciformes) referring to the department of avian medicine (the faculty of veterinary medicine of Shahid Chamran University of Ahvaz) were analyzed. The samples were directly inoculated on niger seed agar (NSA) and also enriched in brain heart infusion broth and then inoculated on NSA. Dark brown colonies suspected to C. neoformans subcultured on saborouds dextrose agar and pure cultures subjected to molecular (polymerase chain reaction (PCR)) diagnosis. For detection of C. neoformans, primer sets that targeting the CNLAC1 gene were selected and nested PCR was conducted. For identification of C. neoformans varieties, a primer set targeting the STR1 gene was selected. For more accurate confirmation, the purified PCR products of some isolates were also sequenced, and based on the gene sequences, all of the isolates belonged to C. neoformans variety grubii (var. grubii)(serotype A). Totally 16 out of 80 pigeon samples (20%) were contaminated with C. neoformans. The results in pigeons disclosed a 98.64% identity when compared with other strains of C. neoformans (CN1525, T4, and T1) which were previously deposited in GenBank from Italy and Thailand. Also, 21 out of 233 samples from Psittaciformes (9.01%) were contaminated with C. neoformans. The results in Psittaciformes disclosed a 99.7% identity when compared with other strains of C. neoformans (TIMM1313, IFM5882, CN1525, etc.) which were previously deposited in GenBank from Japan and Italy, etc. In the present study, the samples belonging to the passerine order were free of C. neoformans infection. According to the results, C. neoformans is prevalent in pigeon flocks and pet birds including Psittaciformes in the Ahvaz area, and should be considered by pigeon and captive bird breeders, veterinarians, and public health organizations in Ahvaz. The cryptococcus species isolated from captive birds and pigeons could be potential pathogens in humans.

Population diversity and virulence characteristics of Cryptococcus neoformans/C. gattii species complexes isolated during the pre-HIV-pandemic era

Cryptococcosis has become a major global health problem since the advent of the HIV pandemic in 1980s. Although its molecular epidemiology is well-defined, using isolates recovered since then, no pre-HIV-pandemic era epidemiological data exist. We conducted a molecular epidemiological study using 228 isolates of the C. neoformans/C. gattii species complexes isolated before 1975. Genotypes were determined by URA5 restriction fragment length polymorphism analysis and multi-locus sequence typing. Population genetics were defined by nucleotide diversity measurements, neutrality tests, and recombination analysis. Growth at 37°C, melanin synthesis, capsule production, and urease activity as virulence factors were quantified. The pre-HIV-pandemic isolates consisted of 186 (81.5%) clinical, 35 (15.4%) environmental, and 7 (3.1%) veterinary isolates. Of those, 204 (89.5%) belonged to C. neoformans VNI (64.0%), VNII (14.9%) and VNIV (10.5%) while 24 (10.5%) belonged to C. gattii VGIII (7.5%), VGI (2.6%) and VGII (0.5%). Among the 47 sequence types (STs) identified, one of VNII and 8 of VNIV were novel. ST5/VNI (23.0%) in C. neoformans and ST75/VGIII (25.0%) in C. gattii were the most common STs in both species complexes. Among C. neoformans, VNIV had the highest genetic diversity (Hd = 0.926) and the minimum recombination events (Rm = 10), and clinical isolates had less genetic diversity (Hd = 0.866) than environmental (Hd = 0.889) and veterinary isolates (Hd = 0.900). Among C. gattii, VGI had a higher nucleotide diversity (π = 0.01436) than in VGIII (π = 0.00328). The high-virulence genotypes (ST5/VNI and VGIIIa/serotype B) did not produce higher virulence factors levels than other genotypes. Overall, high genetic variability and recombination rates were found for the pre-HIV-pandemic era among strains of the C. neoformans/C. gattii species complexes. Whole genome analysis and in vivo virulence studies would clarify the evolution of the genetic diversity and/or virulence of isolates of the C. neoformans/C. gattii species complexes during the pre- and post-HIV-pandemic eras.

Since the beginning of the HIV pandemic in 1980, infections due to isolates of the Cryptococcus neoformans/C. gattii species complexes have caused many deaths worldwide, especially in the HIV-infected population. Annually, approximately one-third, of all AIDS-related deaths,—representing more than 1,000,000 cases,—are caused by cryptococcosis. Since 1980, extensive molecular epidemiological surveys have been conducted, and the VNI molecular type has been found to be responsible for more than 90% of cryptococcosis in HIV patients. Whether the high VNI prevalence is associated with the HIV pandemic remains controversial as information on the isolates of the pre-HIV pandemic era is lacking. Therefore, this study of the molecular epidemiology and in vitro characteristics of the strains from the pre-HIV-pandemic era was undertaken. We found that only 64% of cryptococcosis was caused by VNI, and 9 sequence types existed only in the pre-HIV pandemic era. Unlike what was already known about the strains collected during the HIV pandemic era, ST5 and VGIIIa,—supposedly high virulence genotypes,—did not express higher virulence factors than other genotypes. These results implied that the HIV pandemic altered both the molecular epidemiology and virulence of Cryptococcus neoformans/C. gattii species complexes have been altered during HIV pandemic. However, detailed mechanism of these alteration remains to be deciphered further.

Molecular Epidemiology Reveals Low Genetic Diversity among Cryptococcus neoformans Isolates from People Living with HIV in Lima, Peru, during the Pre-HAART Era

Cryptococcosis, a mycosis presenting mostly as meningoencephalitis, affecting predominantly human immunodeficiency virus (HIV)-infected people, is mainly caused by Cryptococcus neoformans. The genetic variation of 48 C. neoformans isolates, recovered from 20 HIV-positive people in Lima, Peru, during the pre-highly active antiretroviral therapy (HAART) era, was studied retrospectively. The mating type of the isolates was determined by PCR, and the serotype by agglutination and CAP59-restriction fragment length polymorphism (RFLP). Genetic diversity was assessed by URA5-RFLP, PCR-fingerprinting, amplified fragment length polymorphism (AFLP), and multilocus sequence typing (MLST). All isolates were mating type alpha, with 39 molecular type VNI, seven VNII, corresponding to C. neoformans var. grubii serotype A, and two VNIII AD hybrids. Overall, the cryptococcal population from HIV-positive people in Lima shows a low degree of genetic diversity. In most patients with persistent cryptococcal infection, the same genotype was recovered during the follow-up. In four patients with relapse and one with therapy failure, different genotypes were found in isolates from the re-infection and from the isolate recovered at the end of the treatment. In one patient, two genotypes were found in the first cryptococcosis episode. This study contributes data from Peru to the ongoing worldwide population genetic analysis of Cryptococcus.

Pathogen and host genetics underpinning cryptococcal disease

Cryptococcosis is a severe fungal disease causing 220,000 cases of cryptococcal meningitis yearly. The etiological agents of cryptococcosis are taxonomically grouped into at least two species complexes belonging to the genus Cryptococcus. All of these yeasts are environmentally ubiquitous fungi (often found in soil, leaves and decaying wood, tree hollows, and associated with bird feces especially pigeon guano). Infection in a range of animals including humans begins following inhalation of spores or aerosolized yeasts. Recent advances provide fundamental insights into the factors from both the pathogen and its hosts which influence pathogenesis and disease. The complex interactions leading to disease in mammalian hosts have also updated from the availability of better genomic tools and datasets. In this review, we discuss recent genetic research on Cryptococcus, covering the epidemiology, ecology, and evolution of Cryptococcus pathogenic species. We also discuss the insights into the host immune response obtained from the latest genetic modified host models as well as insights from monogenic disorders in humans. Finally we highlight outstanding questions that can be answered in the near future using bioinformatics and genomic tools.

Comparative antifungal susceptibility analyses of Cryptococcus neoformans VNI and Cryptococcus gattii VGII from the Brazilian Amazon Region by the Etest, Vitek 2, and the Clinical and Laboratory Standards Institute broth microdilution methods

Early diagnosis, efficient clinical support, and proper antifungal therapy are essential to reduce death and sequels caused by cryptococcosis. The emergence of resistance to the antifungal drugs commonly used for cryptococcosis treatment is an important issue of concern. Thus, the in vitro antifungal susceptibility of clinical strains from northern Brazil, including C. neoformans VNI (n = 62) and C. gattii VGII (n = 37), to amphotericin B (AMB), 5-flucytosine, fluconazole, voriconazole, and itraconazole was evaluated using the Etest and Vitek 2 systems and the standardized broth microdilution (CLSI-BMD) methodology. According to the CLSI-BMD, the most active in vitro azole was voriconazole (C. neoformans VNI modal MIC of 0.06 μg/ml and C. gattii VGII modal MIC of 0.25 μg/ml), and fluconazole was the least active (modal MIC of 4 μg/ml for both fungi). Modal MICs for amphotericin B were 1 μg/ml for both fungi. In general, good essential agreement (EA) values were observed between the methods. However, AMB presented the lowest EA between CLSI-BMD and Etest for C. neoformans VNI and C. gattii VGII (1.6% and 2.56%, respectively, P < .05 for both). Considering the proposed Cryptococcus spp. epidemiological cutoff values, more than 97% of the studied isolates were categorized as wild-type for the azoles. However, the high frequency of C. neoformans VNI isolates in the population described here that displayed non-wild-type susceptibility to AMB is noteworthy. Epidemiological surveillance of the antifungal resistance of cryptococcal strains is relevant due to the potential burden and the high lethality of cryptococcal meningitis in the Amazon region.

Environmental Factors That Contribute to the Maintenance of Cryptococcus neoformans Pathogenesis

The ability of microorganisms to colonise and display an intracellular lifestyle within a host body increases their fitness to survive and avoid extinction. This host–pathogen association drives microbial evolution, as such organisms are under selective pressure and can become more pathogenic. Some of these microorganisms can quickly spread through the environment via transmission. The non-transmittable fungal pathogens, such as Cryptococcus, probably return into the environment upon decomposition of the infected host. This review analyses whether re-entry of the pathogen into the environment causes restoration of its non-pathogenic state or whether environmental factors and parameters assist them in maintaining pathogenesis. Cryptococcus (C.) neoformans is therefore used as a model organism to evaluate the impact of environmental stress factors that aid the survival and pathogenesis of C. neoformans intracellularly and extracellularly.

Genotypic diversity in clinical and environmental isolates of Cryptococcus neoformans from India using multilocus microsatellite and multilocus sequence typing

BACKGROUND

Cryptococcus neoformans is the leading cause of cryptococcal meningitis in HIV/AIDS patients. As infections in humans are predominantly caused by the inhalation of basidiospores from environmental sources, therefore, analysing the population structure of both clinical and environmental populations of C neoformans can increase our understanding of the molecular epidemiology of cryptococcosis.

OBJECTIVE

To investigate the genotypic diversity and antifungal susceptibility profile of a large collection of C neoformans isolates (n = 523) from clinical and environmental sources in India between 2001 and 2014.

MATERIALS AND METHODS

Cryptococcus neoformans isolates were genotyped by AFLP, microsatellite typing (MLMT) and MLST. In vitro antifungal susceptibility for standard antifungals was undertaken using CLSI M27-A3.

RESULTS

All isolates were C neoformans, AFLP1/VNI and exhibited mating-type MATα. MLMT revealed that the majority of isolates belonged to microsatellite cluster (MC) MC3 (49%), followed by MC1 (35%), and the remaining isolates fell in 11 other MC types. Interestingly, two-thirds of clinical isolates were genotype MC3 and only 17% of them were MC1, whereas majority of environmental strains were MC1 (54%) followed by MC3 (16%). Overall, MLST assigned 5 sequence types (STs) among all isolates and ST93 was the most common (n = 76.7%), which was equally distributed in both HIV-positive and HIV-negative patients. Geometric mean MICs revealed that isolates in MC1 were significantly less (P < .05) susceptible to amphotericin B, 5-flucytosine, itraconazole, posaconazole and isavuconazole than isolates in MC3.

CONCLUSIONS

The study shows a good correlation between MLMT and MLST genotyping methods. Further, environmental isolates were genetically more diverse than clinical isolates.

Molecular epidemiology and antifungal susceptibility profiles of clinical Cryptococcus neoformans/Cryptococcus gattii species complex

Introduction. Limited data regarding the epidemiology and susceptibility profiles of cryptococcosis are available in the Middle East.Aim. Our study aimed to evaluate the molecular diversity, mating types and antifungal susceptibility pattern of Cryptococcus species (n=14) isolated from 320 suspected patients with cryptococcosis.Methodology. The URA5 gene was subjected to restriction fragment length polymorphism and sequence analysis. In addition, in vitro antifungal susceptibility testing was performed by Clinical and Laboratory Standards Institute (CLSI) M27-A4 and M59 guidelines.Results. Overall, 14 (4.4 %) patients were confirmed as cryptococcosis. Based on molecular type, 85.7 and 14.3 % of the isolates were C. neoformans VN I and VN II, respectively. Phylogenetic analysis of URA5 gene sequences revealed clustering of VN I and VN II isolates into two distinct clades with a substantial difference within each molecular type. Voriconazole and 5-fluorocytosine, respectively, had the lowest (0.031 μg ml^-1) and highest (8 µg ml^-1) MICs. The epidemiological cutoff values (ECVs) for amphotericin B, fluconazole, voriconazole and 5-fluorocytosine encompassed ≥97 % of all 14 C. neoformans VN I species. However, according to the CLSI document M59, ECVs for itraconazole (7; 50 % of the isolates) and for posaconazole (1; 7.1 % of the isolate), were one log2 dilution higher than the wild type range. Combinations of amphotericin B with 5-fluorocytosine, amphotericin B with fluconazole and fluconazole with 5-fluorocytosine exhibited synergistic effects against 37, 31 and 12.5 % of the isolates, respectively.Conclusion. Our findings may significantly contribute to the development of management strategies for patients at a higher risk of cryptococcosis, particularly HIV-positive individuals.

Cryptococcus genetic diversity and mixed infections in Ivorian HIV patients: A follow up study

Genetic diversity analyses were performed by sero-genotyping and multi-locus sequence typing on 252 cryptococcal isolates from 13 HIV-positive Ivorian patients followed-up for cryptococcal meningitis. Antifungal susceptibility analyses were performed according to the CLSI M27A3 method. The majority (67.8%) of the isolates belonged to the Cryptococcus neoformans (serotype A) species complex, with 93% being VNI and 7% being VNII. Cryptococcus deuterogattii VGII (serotype B) represented 16.7% of the strains, while C. neoformans/C. deneoformans VNIII (serotype AD) hybrids accounted for 15.1% of the strains. One strain (0.4%) was not identifiable. Nine different sequence types (STs 5, 6, 23, 40, 93, 207, 311, and a new ST; 555) were identified in the C. neoformans population, while the C. deuterogattii population comprised the single ST 173. The distribution of the strains showed that, while the majority of patients (9/13) harboured a single sequence type, 4 patients showed mixed infections. These patients experienced up to 4 shifts in strain content either at the species and/or ST level during their follow-up. This evolution of diversity over time led to the co-existence of up to 3 different Cryptococcus species and 4 different ST within the same individual during the course of infection. Susceptibility testing showed that all strains were susceptible to amphotericin B while 3.6% of them had a none-wild type phenotype to 5-flucytosine. Concerning fluconazole, 2.9% of C.neoformans serotype A strains and 2.4% of C. deuterogattii had also respectively a none-wild type phenotype to this molecule. All C. neoformans x C. deneoformans serotype AD hybrids had however a wild type phenotype to fluconazole. The present study showed that mixed infections exist and could be of particular importance for care outcomes. Indeed, (i) the different Cryptococcus species are known to exhibit different virulence and different susceptibility patterns to antifungal drugs and (ii) the strains genetic diversity within the samples may influence the susceptibility to antifungal treatment.

Identification of Pathogen Genomic Differences That Impact Human Immune Response and Disease during Cryptococcus neoformans Infection

Patient outcomes during infection are due to a complex interplay between the quality of medical care, host immunity factors, and the infecting pathogen's characteristics. To probe the influence of pathogen genotype on human survival, immune response, and other parameters of disease, we examined Cryptococcus neoformans isolates collected during the Cryptococcal Optimal Antiretroviral Therapy (ART) Timing (COAT) Trial in Uganda. We measured human participants' survival, meningitis disease parameters, immunologic phenotypes, and pathogen in vitro growth characteristics. We compared those clinical data to whole-genome sequences from 38 C. neoformans isolates of the most frequently observed sequence type (ST), ST93, in our Ugandan participant population and to sequences from an additional 18 strains of 9 other sequence types representing the known genetic diversity within the Ugandan Cryptococcus clinical isolates. We focused our analyses on 652 polymorphisms that were variable among the ST93 genomes, were not in centromeres or extreme telomeres, and were predicted to have a fitness effect. Logistic regression and principal component analysis identified 40 candidate Cryptococcus genes and 3 hypothetical RNAs associated with human survival, immunologic response, or clinical parameters. We infected mice with 17 available KN99α gene deletion strains for these candidate genes and found that 35% (6/17) directly influenced murine survival. Four of the six gene deletions that impacted murine survival were novel. Such bedside-to-bench translational research identifies important candidate genes for future studies on virulence-associated traits in human Cryptococcus infections.IMPORTANCE Even with the best available care, mortality rates in cryptococcal meningitis range from 20% to 60%. Disease is often due to infection by the fungus Cryptococcus neoformans and involves a complex interaction between the human host and the fungal pathogen. Although previous studies have suggested genetic differences in the pathogen impact human disease, it has proven quite difficult to identify the specific C. neoformans genes that impact the outcome of the human infection. Here, we take advantage of a Ugandan patient cohort infected with closely related C. neoformans strains to examine the role of pathogen genetic variants on several human disease characteristics. Using a pathogen whole-genome sequencing approach, we showed that 40 C. neoformans genes are associated with human disease. Surprisingly, many of these genes are specific to Cryptococcus and have unknown functions. We also show deletion of some of these genes alters disease in a mouse model of infection, confirming their role in disease. These findings are particularly important because they are the first to identify C. neoformans genes associated with human cryptococcal meningitis and lay the foundation for future studies that may lead to new treatment strategies aimed at reducing patient mortality.

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.

Cryptococcus gattii VGII isolated from native forest and river in Northern Brazil

BACKGROUND

Cryptococcosis is a global invasive mycosis associated with significant morbidity and mortality. In the northern region of Brazil, this disease is caused by Cryptococcus neoformans genotype VNI and Cryptococcus gattii genotype VGII. However, few environmental studies have been conducted in this large tropical area.

AIMS

This study was performed to isolate, genotype, and determine the frequency of cryptococcal agents in environmental samples near Manaus, Amazonas, Brazil.

METHODS

A total of 970 environmental samples (290 from soil, 290 from decaying plants, 5 from insects, 280 from the Negro river, and 105 from small streams within the city of Manaus) were collected and plated on Niger seed agar. In addition, 20 sub-cultures obtained from each positive sample were analyzed by PCR-RFLP (URA5) and PCR for genotyping and determination of mating type.

RESULTS

Six samples were positive for isolates from the C. gattii species complex. Of those, three samples were from Adolpho Ducke Forest Reserve and three were from the Negro river. All isolates were C. gattii genotype VGII (mating type MATα).

CONCLUSION

Genotype VGII proved to be the most important genotype found in the environmental samples. The genotype VGII has been described as one of the most virulent and less susceptible to antifungals and responsible for important outbreaks. This is the first study to demonstrate isolation of C. gattii (VGII) from the Negro river.

First isolation and molecular characterization of Cryptococcus neoformans var. grubii in excreta of birds in the urban perimeter of the Municipality of Popayán, Colombia

BACKGROUND

Cryptococcosis is a systemic opportunistic mycosis, caused by Cryptococcus neoformans and Cryptococcus gattii, which affects mainly the central nervous system of immunocompromised patients; no reports have been made on the isolation of the fungus from the environment of Popayán, Colombia.

AIMS

The main objective of this investigation was to determinate the incidence of C. neoformans in the urban perimeter in the City of Popayán, Colombia.

METHODS

A total of 303 samples from droppings of Columba livia and Bubulcus ibis were collected between September 2012 and June 2013. The samples were processed by conventional techniques; identification of colonies was performed by biochemical tests, and molecular patterns were determined by PCR fingerprinting with the primer (GTG)₅ and restriction fragment length polymorphism (RFLP) of the gene URA₅.

RESULTS

A total of 118 (38.94%) samples were positive for Cryptococcus in excreta of C. livia, and 361 strains belonging to Cryptococcus neoformans var. grubii were isolated. From the latter, 99.2% corresponded to the molecular pattern VNI and 0.8% to VNII, with an increased occurrence (24.4%) at a temperature of 22.5°C and a humidity of 60.8%. The excreta of B. ibis did not show the presence of the fungus.

CONCLUSIONS

C. livia excreta is a key environmental niche for C. neoformans var. grubii, type VNI, supporting growth and reproduction, and serving as a major source of infection for susceptible populations in Popayán. This represents the first report on the isolation of the agent of cryptococcosis from the environment in this region, with a significant prevalence in bird excreta.

MLST reveals a clonal population structure for Cryptococcus neoformans molecular type VNI isolates from clinical sources in Amazonas, Northern-Brazil

Cryptococcosis is considered endemic in Amazonas state, occurring more frequently in individuals with AIDS, who are predominantly infected by Cryptococcus neoformans molecular type VNI. Infections by Cryptococcus gattii VGII predominate in immunocompetent hosts from the American continent and are associated with outbreaks in North America, particularly the subtypes VGIIa and VGIIb, which are also present in the Brazilian Amazon region. Despite few environmental studies, several aspects of the molecular epidemiology of this disease in Amazonas remain unclear, including the limited use of multilocus sequence typing (MLST) to evaluate the genetic population structure of clinical isolates, mainly C. neoformans. Therefore, we used MLST to identify the sequence types of 38 clinical isolates of C. neoformans VNI and C. gattii VGII and used phylogenetic analysis to evaluate their genetic relationship to global isolates. Records of 30 patients were analyzed to describe the current scenario of cryptococcosis in the region and their associations with the different subtypes. Broth microdilution was also performed to determine the susceptibility profile to the antifungals amphotericin B, fluconazole and itraconazole. MLST identified that patients with HIV (n = 26) were exclusively affected by VNI strains with ST93, and among the VGII strains (n = 4), three STs (ST5, ST172 and the new ST445) were identified. An in-hospital lethality of 54% was observed in the HIV group, and there were no significant differences in the clinical aspects of the disease between the HIV and non-HIV groups of patients. In addition, all isolates were susceptible to the antifungals tested. Therefore, in Amazonas state, VNI isolates are a genetically monotypic group, with ST93 being highly important in HIV individuals.

Tracing Genetic Exchange and Biogeography of Cryptococcus neoformans var. grubii at the Global Population Level

Cryptococcus neoformans var. grubii is the causative agent of cryptococcal meningitis, a significant source of mortality in immunocompromised individuals, typically human immunodeficiency virus/AIDS patients from developing countries. Despite the worldwide emergence of this ubiquitous infection, little is known about the global molecular epidemiology of this fungal pathogen. Here we sequence the genomes of 188 diverse isolates and characterize the major subdivisions, their relative diversity, and the level of genetic exchange between them. While most isolates of C. neoformans var. grubii belong to one of three major lineages (VNI, VNII, and VNB), some haploid isolates show hybrid ancestry including some that appear to have recently interbred, based on the detection of large blocks of each ancestry across each chromosome. Many isolates display evidence of aneuploidy, which was detected for all chromosomes. In diploid isolates of C. neoformans var. grubii (serotype AA) and of hybrids with C. neoformans var. neoformans (serotype AD) such aneuploidies have resulted in loss of heterozygosity, where a chromosomal region is represented by the genotype of only one parental isolate. Phylogenetic and population genomic analyses of isolates from Brazil reveal that the previously "African" VNB lineage occurs naturally in the South American environment. This suggests migration of the VNB lineage between Africa and South America prior to its diversification, supported by finding ancestral recombination events between isolates from different lineages and regions. The results provide evidence of substantial population structure, with all lineages showing multi-continental distributions; demonstrating the highly dispersive nature of this pathogen.

Molecular epidemiology of cryptococcal genotype VNIc/ST5 in Siriraj Hospital, Thailand

Despite the strong association between Cryptococcus neoformans infection and the Human immunodeficiency virus (HIV) status of patients globally, most cryptococcosis cases in Far East Asia occur in non-HIV individuals. Molecular epidemiological studies, using multilocus sequence typing (MLST), have shown that more than 95% of cryptococcal strains belong to a specific subtype of VNI. However, this association has never been specifically examined in other parts of Asia. Therefore, in this study, we investigated the VNIc/ST5 genotype distribution among cryptococcosis patients in Thailand. Fifty-one C. neoformans isolates were collected from clinical samples in Siriraj Hospital, Bangkok, Thailand. The strains were predominantly isolated from HIV-positive patients (88.57%) and all were molecular type VNI MATα. An MLST analysis identified five sequence types (ST) in Siriraj Hospital, of which ST4 (45.10%) and ST6 (35.29%) were most common, and ST5 (15.69%), ST32 (1.96%), and ST93 (1.96) were less common. Contrary to reports from Far East Asia, ST5 was predominantly (83.33%) found in HIV patients (P = 0.657), and there was no significant change in the prevalence of ST5 over the past 10 years (P = 0.548). A further analysis of comorbidities showed higher morbidity and delays in the cryptococcal diagnosis in patients with tuberculosis coinfection or without HIV. Our study suggests that although the Thai population is genetically closely related to the Far East Asian population, ST5 is not associated with non-HIV status in Thailand. Therefore, this association may not be related to the host’s genetic background. However, its mechanism remains unclear.

ANTIFUNGAL SUSCEPTIBILITY TESTING AND GENOTYPING CHARACTERIZATION OF Cryptococcus neoformans AND gattii ISOLATES FROM HIV-INFECTED PATIENTS OF RIBEIRÃO PRETO, SÃO PAULO, BRAZIL

Cryptococcosis is a leading invasive fungal infection in immunocompromised patients. Considering the high prevalence and severity of these infections in immunocompromised patients attended at HC-FMRP-USP, the present research aimed to characterize the clinical isolates of Cryptococcus strains by biochemical and molecular methods and evaluate antifungal susceptibility of clinical isolates. Fifty isolates from 32 HIV-positive patients were obtained at HC-FMRP-USP. Most of the isolates (78.1%) were identified as C. neoformans, and 100% of C. neoformans and C. gattii strains were susceptible to amphotericin B, ketoconazole and fluconazole. All isolates were classified as serotype A (grubbii variety) by PCR and most of them were characterized in mating type MATa. PCR analysis of specific M13 microsatellite sequence revealed that VNI type was predominant among C. neoformans, while VGII was predominant among C. gattii. The strains did not show a significant resistance to the antifungals tested, and Canavanine-Glycine-Bromthymol Blue Agar (CGB) proved to be a reliable test presenting a good correlation with the molecular characterization. C. neoformans isolated from disseminated infections in the same patient showed molecular identity when different anatomical sites were compared; besides, the studied strains did not present a significant increase in resistance to antifungal agents. In addition, the homogeneity of the molecular types and detection of the mating types suggested a low possibility of crossing among the strains.

MLST and Whole-Genome-Based Population Analysis of Cryptococcus gattii VGIII Links Clinical, Veterinary and Environmental Strains, and Reveals Divergent Serotype Specific Sub-populations and Distant Ancestors

The emerging pathogen Cryptococcus gattii causes life-threatening disease in immunocompetent and immunocompromised hosts. Of the four major molecular types (VGI-VGIV), the molecular type VGIII has recently emerged as cause of disease in otherwise healthy individuals, prompting a need to investigate its population genetic structure to understand if there are potential genotype-dependent characteristics in its epidemiology, environmental niche(s), host range and clinical features of disease. Multilocus sequence typing (MLST) of 122 clinical, environmental and veterinary C. gattii VGIII isolates from Australia, Colombia, Guatemala, Mexico, New Zealand, Paraguay, USA and Venezuela, and whole genome sequencing (WGS) of 60 isolates representing all established MLST types identified four divergent sub-populations. The majority of the isolates belong to two main clades, corresponding either to serotype B or C, indicating an ongoing species evolution. Both major clades included clinical, environmental and veterinary isolates. The C. gattii VGIII population was genetically highly diverse, with minor differences between countries, isolation source, serotype and mating type. Little to no recombination was found between the two major groups, serotype B and C, at the whole and mitochondrial genome level. C. gattii VGIII is widespread in the Americas, with sporadic cases occurring elsewhere, WGS revealed Mexico and USA as a likely origin of the serotype B VGIII population and Colombia as a possible origin of the serotype C VGIII population. Serotype B isolates are more virulent than serotype C isolates in a murine model of infection, causing predominantly pulmonary cryptococcosis. No specific link between genotype and virulence was observed. Antifungal susceptibility testing against six antifungal drugs revealed that serotype B isolates are more susceptible to azoles than serotype C isolates, highlighting the importance of strain typing to guide effective treatment to improve the disease outcome.

Cryptococcus gattii, which is classically divided into four major molecular types (VGI-VGIV), and two serotypes B and C, is the second most important cause of cryptococcosis. The rising incidence of human and animal cryptococcosis cases caused by molecular type VGIII highlights the need for increased vigilance. In this study, we characterized a large set of C. gattii VGIII isolates. Genetic analysis revealed four diverging sub-populations, which were primarily associated with serotype B or C, and very likely originated from endemic regions in Colombia, Mexico and the USA. Differences in virulence and antifungal susceptibility between serotypes may result in different disease outcomes since serotype B isolates were more virulent in mice than serotype C isolates, but serotype C isolates were less susceptible to azoles, the primary treatment for uncomplicated cryptococcosis. Identification of cryptococcal serotype and molecular type in clinical practice has the potential to guide treatment regimens and hence reduce morbidity and mortality in both sporadic cases and those associated with outbreaks. Our study significantly contributes to the understanding of the epidemiology, genetics and pathogenesis of Cryptococcus and cryptococcosis.

Molecular typing of environmental Cryptococcus neoformans/C. gattii species complex isolates from Manaus, Amazonas, Brazil

Cryptococcus neoformans and Cryptococcus gattii are the main causative agents of cryptococcosis, a systemic fungal disease that affects internal organs and skin, and which is acquired by inhalation of spores or encapsulated yeasts. It is currently known that the C. neoformans/C. gattii species complex has a worldwide distribution, however, some molecular types seem to prevail in certain regions. Few environmental studies of Cryptococcus have been conducted in the Brazilian Amazon. This is the first ecological study of the pathogenic fungi C. neoformans/C. gattii species complex in the urban area of Manaus, Amazonas, Brazil. A total of 506 samples from pigeon droppings (n = 191), captive bird droppings (n = 60) and tree hollows (n = 255) were collected from June 2012 to January 2014 at schools and public buildings, squares, pet shops, households, the zoo and the bus station. Samples were plated on niger seed agar (NSA) medium supplemented with chloramphenicol and incubated at 25°C for 5 days. Dark-brown colonies were isolated and tested for thermotolerance at 37°C, cycloheximide resistance and growth on canavanine-glycine-bromothymol blue agar. Molecular typing was done by PCR-RFLP. Susceptibility to the antifungal drugs amphotericin B, fluconazole, itraconazole and ketoconazole was tested using Etest(®) strips. In total, 13 positive samples were obtained: one tree hollow (C. gattiiVGII), nine pigeon droppings (C. neoformansVNI) and three captive bird droppings (C. neoformansVNI). The environmental cryptococcal isolates found in this study were of the same molecular types as those responsible for infections in Manaus.

Eucalyptus Tree: A Potential Source of Cryptococcus neoformans in Egyptian Environment

In Egypt, the River Red Gum (Eucalyptus camaldulensis) is a well-known tree and is highly appreciated by the rural and urban dwellers. The role of Eucalyptus trees in the ecology of Cryptococcus neoformans is documented worldwide. The aim of this survey was to show the prevalence of C. neoformans during the flowering season of E. camaldulensis at the Delta region in Egypt. Three hundred and eleven samples out of two hundred Eucalyptus trees, including leaves, flowers, and woody trunks, were collected from four governorates in the Delta region. Thirteen isolates of C. neoformans were recovered from Eucalyptus tree samples (4.2%). Molecular identification of C. neoformans was done by capsular gene specific primer CAP64 and serotype identification was done depending on LAC1 gene. This study represents an update on the ecology of C. neoformans associated with Eucalyptus tree in Egyptian environment.

Comparison of biotyping methods as alternative identification tools to molecular typing of pathogenic Cryptococcus species in sub-Saharan Africa

Cryptococcal meningitis is the leading fungal infection and AIDS defining opportunistic illness in patients with late stage HIV infection, particularly in South-East Asia and sub-Saharan Africa. Given the high mortality, clinical differences and the extensive ecological niche of Cryptococcus neoformans and Cryptococcus gattii species complexes, there is need for laboratories in sub-Sahara African countries to adopt new and alternative reliable diagnostic algorithms that rapidly identify and distinguish these species. We biotyped 74 and then amplified fragment length polymorphism (AFLP) genotyped 66 Cryptococcus isolates from a cohort of patients with HIV-associated cryptococcal meningitis. C. gattii sensu lato was isolated at a prevalence of 16.7% (n = 11/66) and C. neoformans sensu stricto was responsible for 83.3% (n = 55/66) of the infections. l-Canavanine glycine bromothymol blue, yeast-carbon-base-d-proline-d-tryptophan and creatinine dextrose bromothymol blue thymine were able to distinguish pathogenic C. gattii sensu lato from C. neoformans sensu stricto species when compared with AFLP genotyping. This study demonstrates high C. gattii sensu lato prevalence in Zimbabwe. In addition, biotyping methods can be used as alternative diagnostic tools to molecular typing in resource-limited areas for differentiating pathogenic Cryptococcus species.

What makes Cryptococcus gattii a pathogen?

Cryptococcosis is an invasive fungal infection of humans and other animals, typically caused by the species Cryptococcus neoformans in patients with impaired immunity. However, there is growing recognition of the importance of the related species C. gattii in causing infections in apparently immunocompetent individuals. In particular, an ongoing outbreak of cryptococcal disease in the Pacific Northwest region, which started in 1999, has driven an intense research effort into this previously neglected pathogen. Here, we discuss some of the recent discoveries in this organism from the Pacific Northwest region and highlight areas for future investigation.

HIV/AIDS-Associated Cryptococcosis in Portugal Spanning the Pre- to Post-HAART Era: A Retrospective Assessment at the Genotypic Level Based on URA5-RFLP

Cryptococcosis caused by the fungus Cryptococcus neoformans is an opportunistic mycosis, infecting mainly immunodepressed individuals. Molecular epidemiology studies of cryptococcosis in Europe are limited. This paper presents a retrospective study of cryptococcosis in 105 cryptococcal isolates from two hospitals in Lisbon, Portugal, among HIV/AIDS patients, from 1991 to 2007. Among these patients, the number of cases of cryptococcosis increased from 5.1 to 6.9 cases per year from the pre- to post-highly active antiretroviral therapy (HAART) era. As expected, the median age of the patients increased, from 32 (mean: 33 ± 8) to 39 (mean: 41 ± 10) years, and the ratio of male to female patients remained high (7.7 and 7.6, respectively). Strain genotyping based on restriction fragment length polymorphism of the orotidine monophosphate pyrophosphorylase (URA5-RFLP) gene showed that, in general, the relative frequencies of the genotypes VNI-IV are similar to those from other European countries. These frequencies were, respectively, for the pre- and post-HAART periods: 41.7 and 43.5 % for VNI; 2.8 and 17.4 % for VNII; 38.9 and 30.4 % for VNIII; 16.7 and 7.2 % for VNIV and 0 and 1.4 % for VGII. Some apparent although statistically insignificant differences among these values were observed between both periods. The genotypic frequencies were not also statistically different according to the patients' gender or age range. Of note are the high proportion of VNIII isolates (common in Europe) and the high increase in the frequency of the VNII genotype in the post-HAART. Ultimately, these results may have implications in disease therapy, management and control.

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.

Cryptococcosis Serotypes Impact Outcome and Provide Evidence of Cryptococcus neoformans Speciation

Cryptococcus neoformans is a human opportunistic fungal pathogen causing severe disseminated meningoencephalitis, mostly in patients with cellular immune defects. This species is divided into three serotypes: A, D, and the AD hybrid. Our objectives were to compare population structures of serotype A and D clinical isolates and to assess whether infections with AD hybrids differ from infections with the other serotypes. For this purpose, we analyzed 483 isolates and the corresponding clinical data from 234 patients enrolled during the CryptoA/D study or the nationwide survey on cryptococcosis in France. Isolates were characterized in terms of ploidy, serotype, mating type, and genotype, utilizing flow cytometry, serotype- and mating type-specific PCR amplifications, and multilocus sequence typing (MLST) methods. Our results suggest that C. neoformans serotypes A and D have different routes of multiplication (primarily clonal expansion versus recombination events for serotype A and serotype D, respectively) and important genomic differences. Cryptococcosis includes a high proportion of proven or probable infections (21.5%) due to a mixture of genotypes, serotypes, and/or ploidies. Multivariate analysis showed that parameters independently associated with failure to achieve cerebrospinal fluid (CSF) sterilization by week 2 were a high serum antigen titer, the lack of flucytosine during induction therapy, and the occurrence of mixed infection, while infections caused by AD hybrids were more likely to be associated with CSF sterilization. Our study provides additional evidence for the possible speciation of C. neoformans var. neoformans and grubii and highlights the importance of careful characterization of causative isolates.

Cryptococcus neoformans is an environmental fungus causing severe disease, estimated to be responsible for 600,000 deaths per year worldwide. This species is divided into serotypes A and D and an AD hybrid, and these could be considered two different species and an interspecies hybrid. The objectives of our study were to compare population structures of serotype A and serotype D and to assess whether infections with AD hybrids differ from infections with serotype A or D isolates in terms of clinical presentation and outcome. For this purpose, we used clinical data and strains from patients diagnosed with cryptococcosis in France. Our results suggest that, according to the serotype, isolates have different routes of multiplication and high genomic differences, confirming the possible speciation of serotypes A and D. Furthermore, we observed a better prognosis for infections caused by AD hybrid than those caused by serotype A or D, at least for those diagnosed in France.

Rising to the challenge of multiple Cryptococcus species and the diseases they cause

Cryptococcus neoformans and Cryptococcus gattii are well-studied basidiomyceteous yeasts that are capable of causing disease in healthy and immunocompromised people. The Conference on Cryptococcus and Cryptococcosis (ICCC) is held every three years: the accompanying Special Issue stems from the 9th ICCC and covers a subset of the topics related to these fungi in detail. This conference started with a revised and reduced estimate of disease burden globally, in part due to improved treatment for HIV(+) people. However, mortality from cryptococcosis remains consistently high for those unfortunate to have limited access to therapies or without underlying immunodeficiencies. As such, there are yet still great distances to be covered to address antifungal drug availability, the need for new antifungal agents and the timing and doses of these agents in conjunction with antiviral therapy, underscoring the importance of continued research. A notable point from the 9th ICCC was the research addressing the variation in the pathogen and host populations. Analysis of cryptococcal strain variability, particularly at the molecular level, has resolved distinct lineages with the consequence of a taxonomic revision that divides C. neoformans and C. gattii into seven Cryptococcus species. Similarly, analysis of host factors in so called "immune-competent" individuals revealed previously unrecognized risk factors. Research on these species has established them as important model organisms to understand gene evolution and function in other fungi and eukaryotes. The stage is set for the refinement of research directions, leading ultimately to better treatment of this monophyletic clade of pathogens in the genus Cryptococcus.

Recognition of seven species in the Cryptococcus gattii/Cryptococcus neoformans species complex

Phylogenetic analysis of 11 genetic loci and results from many genotyping studies revealed significant genetic diversity with the pathogenic Cryptococcus gattii/Cryptococcus neoformans species complex. Genealogical concordance, coalescence-based, and species tree approaches supported the presence of distinct and concordant lineages within the complex. Consequently, we propose to recognize the current C. neoformans var. grubii and C. neoformans var. neoformans as separate species, and five species within C. gattii. The type strain of C. neoformans CBS132 represents a serotype AD hybrid and is replaced. The newly delimited species differ in aspects of pathogenicity, prevalence for patient groups, as well as biochemical and physiological aspects, such as susceptibility to antifungals. MALDI-TOF mass spectrometry readily distinguishes the newly recognized species.

Molecular Epidemiology of Invasive Aspergillosis: Lessons Learned from an Outbreak Investigation in an Australian Hematology Unit

Suspected nosocomial Aspergillus fumigatus infections in an Australian hematology unit were investigated by molecular typing of clinical and environmental isolates using polymerase chain reaction fingerprinting, CSP typing, and multilocus microsatellite typing. Only multilocus microsatellite typing revealed that all isolates were genetically distinct. The selection of an appropriate typing method is essential for effective outbreak investigations.

Molecular diagnosis of cryptococcal meningitis in cerebrospinal fluid: comparison of primer sets for Cryptococcus neoformans and Cryptococcus gattii species complex

Aim

This study evaluated the use of polymerase chain reaction for cryptococcal meningitis diagnosis in clinical samples.

Materials and methods

The sensitivity and specificity of the methodology were evaluated using eight Cryptococcus neoformans/C. gattii species complex reference strains and 165 cerebrospinal fluid samples from patients with neurological diseases divided into two groups: 96 patients with cryptococcal meningitis and AIDS; and 69 patients with other neurological opportunistic diseases (CRL/AIDS). Two primer sets were tested (CN4–CN5 and the multiplex CNa70S–CNa70A/CNb49S–CNb-49A that amplify a specific product for C. neoformans and another for C. gattii).

Results

CN4–CN5 primer set was positive in all Cryptococcus standard strains and in 94.8% in DNA samples from cryptococcal meningitis and AIDS group. With the multiplex, no 448-bp product of C. gattii was observed in the clinical samples of either group. The 695 bp products of C. neoformans were observed only in 64.6% of the cryptococcal meningitis and AIDS group. This primer set was negative for two standard strains. The specificity based on the negative samples from the CTL/AIDS group was 98.5% in both primer sets.

Conclusions

These data suggest that the CN4/CN5 primer set was highly sensitive for the identification of C. neoformans/C. gattii species complex in cerebrospinal fluid samples from patients with clinical suspicion of cryptococcal meningitis.

Molecular epidemiology of Cryptococcus neoformans and Cryptococcus gattii in China between 2007 and 2013 using multilocus sequence typing and the DiversiLab system

The purpose of this study was to investigate the molecular characteristics of 83 clinical Cryptococcus neoformans/C. gattii species complex isolated in Beijing, China, between 2007 and 2013. Restriction fragment length polymorphism of the gene URA5 (URA5-RFLP), multilocus sequence typing (MLST), and automated repetitive polymerase chain reaction (rep-PCR; DiversiLab system) were performed to genotype these cryptococcal isolates. There was an excellent correlation amongst the three methods; however, PU157 was assigned as VNII according to URA5-RFLP, while it was classified as VNI by the DiversiLab system analysis. PU157 was finally identified as VNB by seven-locus MLST analysis. Moreover, though AD hybrids could not be processed by MLST, ideal results could be obtained by the DiversiLab system. The genotype VNI accounted for 95.2% (79/83) of isolates. Besides one strain of VNB, VNIII, and VGI each, a strain of VGII was detected in our study, which was isolated from a patient from the temperate region in North China. In addition, the most common MLST sequence type (ST) was ST5, accounting for 91.6% (76/83), followed by ST31, ST63, ST182, ST295, ST296, and ST332. ST295, ST296, and ST332 were new STs. Except for isolate PU157 (VNB), identical results were obtained quickly and accurately through the DiversiLab system compared to MLST and URA5-RFLP. The discovery of VNB and VGII in the temperate climate regions of China suggested that the population structure of C. neoformans and C. gattii should be explored more extensively. Our results also showed that the DiversiLab system can be used in the genotyping of C. neoformans and C. gattii.

Long-term survival of Cryptococcus neoformans and Cryptococcus gattii in stored environmental samples from Colombia

BACKGROUND

Both Cryptococcus neoformans and Cryptococcus gattii have been isolated from a variety of environmental sources in Colombia.

AIM

To determine the viability of C. neoformans/C. gattii isolates in stored soil samples, filtrates and bird droppings from which these yeasts were previously recovered.

METHODS

A total of 964 samples collected between 2003 and 2009, and kept at room temperature were processed. From them, 653 samples were from trees decaying wood, 274 from soil filtrates and 37 from bird droppings. When C. neoformans or C. gattii were recovered, the molecular type of each isolate was established by PCR fingerprinting using the single primer (GTG)5.

RESULTS

Among the processed samples, 161 isolates were recovered. From those, 81 (50.3%) corresponded to C. gattii recovered from decaying wood of Eucalyptus spp., Corymbia ficifolia, Terminalia catappa and Ficus spp. trees, and 80 (49.7%) corresponded to C. neoformans recovered from Ficus spp. and eucalyptus trees, as well as from bird droppings. The most prevalent molecular type among the C. gattii and C. neoformans isolates was VGII and VNI, respectively.

CONCLUSIONS

The re-isolation of C. neoformans/C. gattii from 10-year stored samples suggests that these yeasts are able to keep viable in naturally colonized samples.

Epidemiology of Cryptococcus and cryptococcosis in China

Cryptococcosis is a significant invasive fungal infection with noteworthy morbidity and mortality, primarily caused by Cryptococcus neoformans and Cryptococcus gattii. In China, C. neoformans var. grubii (especially molecular type VNI) is the most common variety in the environment and responsible for the majority of cryptococcal infections. C. gattii infections are quite rare in China and the primary molecular type is VGI, which is closely related to C. gattii isolates in Australia. Interestingly, the majority of cryptococcosis in China were reported in the HIV-uninfected patients (especially immunocompetent hosts). This unique phenomenon may be attributed to multiple polymorphisms in the genes encoding mannose-binding lectin (MBL) and Fc-gamma receptor 2B (FCGR2B) in the Han population, the major ethnic group in China. Compared to immunocompromised patients, immunocompetent patients with cryptococcal meningitis often presented with more intense inflammatory responses and more severe neurological complications, but less fungal burdens and disseminated infection. The overall prognosis, which is independently associated with amphotericin B-based initial therapy, is similar between immunocompetent and immunocompromised patients. In addition, intrathecal administration of amphotericin B has been proved to be an effective adjunctive treatment for cryptococcosis in China.

Galleria mellonella model identifies highly virulent strains among all major molecular types of Cryptococcus gattii

Cryptococcosis is mainly caused by Cryptococcus neoformans. However, the number of cases due to C. gattii is increasing, affecting mainly immunocompetent hosts. C. gattii is divided into four major molecular types, VGI to VGIV, which differ in their host range, epidemiology, antifungal susceptibility and geographic distribution. Besides studies on the Vancouver Island outbreak strains, which showed that the subtype VGIIa is highly virulent compared to the subtype VGIIb, little is known about the virulence of the other major molecular types. To elucidate the virulence potential of the major molecular types of C. gattii, Galleria mellonella larvae were inoculated with ten globally selected strains per molecular type. Survival rates were recorded and known virulence factors were studied. One VGII, one VGIII and one VGIV strain were more virulent (p <0.05) than the highly virulent Vancouver Island outbreak strain VGIIa (CDCR265), 11 (four VGI, two VGII, four VGIII and one VGIV) had similar virulence (p >0.05), 21 (five VGI, five VGII, four VGIII and seven VGIV) were less virulent (p <0.05) while one strain of each molecular type were avirulent. Cell and capsule size of all strains increased markedly during larvae infection (p <0.001). No differences in growth rate at 37°C were observed. Melanin synthesis was directly related with the level of virulence: more virulent strains produced more melanin than less virulent strains (p <0.05). The results indicate that all C. gattii major molecular types exhibit a range of virulence, with some strains having the potential to be more virulent. The study highlights the necessity to further investigate the genetic background of more and less virulent strains in order to recognize critical features, other than the known virulence factors (capsule, melanin and growth at mammalian body temperature), that maybe crucial for the development and progression of cryptococcosis.

Cryptococcosis in kidney transplant recipients in a Chinese university hospital and a review of published cases

BACKGROUND

Cryptococcosis is a severe fungal infection with a high mortality rate among solid-organ transplant recipients. Today, China is among the countries performing the most kidney transplants worldwide, however data on the association of cryptococcosis with kidney transplantation in mainland China remain scarce and fragmented.

METHODS

We retrospectively analyzed cases of culture-confirmed cryptococcosis following kidney transplantation that have occurred at our hospital and reviewed the published cases in China over the last 30 years.

RESULTS

Cryptococcosis in kidney transplant recipients was mainly caused by Cryptococcus neoformans var. grubii VNI strains and occurred most frequently in patients aged 41-50 years (37.9%, 11/29). The average time to infection after kidney transplantation was 5.16 ± 3.97 years. The clinical manifestations were found to be diverse, with slight to moderate headache and fever, meningeal irritation, and high cerebrospinal fluid pressure being relatively common. Physicians should be alert to these symptoms among kidney transplant recipients.

CONCLUSIONS

Cryptococcosis is a serious infection among kidney transplant recipients in mainland China. It has unique characteristics, such as a relatively long time to onset after kidney transplantation, and diverse clinical manifestations. Treatment with intrathecal injection of amphotericin B is considered effective for central nervous system involvement. The findings of this study also highlight the urgent need for multicenter, prospective, and multidisciplinary clinical studies and education on cryptococcosis in kidney transplant recipients in China.

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.

Clinical and microbiological features of cryptococcal meningitis

INTRODUCTION

In this study, the clinical features, underlying diseases and clinical outcomes of patients with cryptococcosis were investigated. In addition, a molecular analysis of the Cryptococcus neoformans species complex isolated from these patients was performed.

METHODS

A prospective study of 62 cases of patients with cryptococcal infection was conducted at the Hospital de Doenças Tropicais de Goiás Dr. Anuar Auad from 2009-2010. Cryptococcal meningitis cases were diagnosed by direct examination and cerebrospinal fluid (CSF) sample culture. The profiling of these patients was assessed. The CSF samples were submitted to India ink preparation and cultured on Sabouraud dextrose agar, and C. neoformans was identified by the production of urease, a positive phenoloxidase test and assimilation of carbohydrates. C. neoformans and C. gattii isolates were distinguished by growth on L-canavanine-glycine-bromothymol blue medium, and molecular analysis was conducted via PCR fingerprinting reactions using M13 and (GACA)4 primers.

RESULTS

From the 62 patients with cryptococcosis, 71 isolates of CSF were obtained; 67 (94.4%) isolates were identified as C. neoformans var. grubii/VNI, and 4 (5.6%) were identified as C. gattii/VGII. Of these patients, 53 had an HIV diagnosis. The incidence of cryptococcosis was higher among patients 20-40 years of age, with 74.2% of the cases reported in males. Cryptococcus-related mortality was noted in 48.4% of the patients, and the symptoms were altered sensorium, headache, fever and stiff neck.

CONCLUSIONS

The high morbidity and mortality observed among patients with cryptococcosis demonstrate the importance of obtaining information regarding the epidemiological profile and clinical course of the disease in the State of Goiás, Brazil.

Geographically structured populations of Cryptococcus neoformans Variety grubii in Asia correlate with HIV status and show a clonal population structure

Cryptococcosis is an important fungal disease in Asia with an estimated 140,000 new infections annually the majority of which occurs in patients suffering from HIV/AIDS. Cryptococcus neoformans variety grubii (serotype A) is the major causative agent of this disease. In the present study, multilocus sequence typing (MLST) using the ISHAM MLST consensus scheme for the C. neoformans/C. gattii species complex was used to analyse nucleotide polymorphisms among 476 isolates of this pathogen obtained from 8 Asian countries. Population genetic analysis showed that the Asian C. neoformans var. grubii population shows limited genetic diversity and demonstrates a largely clonal mode of reproduction when compared with the global MLST dataset. HIV-status, sequence types and geography were found to be confounded. However, a correlation between sequence types and isolates from HIV-negative patients was observed among the Asian isolates. Observations of high gene flow between the Middle Eastern and the Southeastern Asian populations suggest that immigrant workers in the Middle East were originally infected in Southeastern Asia.