Application of proton nuclear magnetic resonance spectroscopy to the study of Cryptococcus and cryptococcosis

Proton nuclear magnetic resonance spectroscopy is a nondestructive technique that identifies chemicals in solution and in living cells. It has been used in cryptococcal research to identify the primary structure of capsular glucuronoxylomannans, link cellular apoptosis susceptibility (CAS) genes to positioning of residues on the mannose backbone of glucuronoxylomannan, and verify that the cryptococcal virulence determinant, phospholipase B, is elaborated in vivo. Promising clinical applications include speciation (Cryptococcus neoformans and Cryptococcus gattii), with preliminary evidence that varieties neoformans and grubii can also be distinguished, non-invasive diagnosis of cerebral cryptococcomas, and, in cases of meningitis, monitoring therapeutic response by analysis of cerebrospinal fluid.

Unique hybrids between the fungal pathogens Cryptococcus neoformans and Cryptococcus gattii

Cryptococcus neoformans and Cryptococcus gattii are yeasts that cause meningoencephalitis, but that differ in host range and geographical distribution. Cryptococcus neoformans occurs world-wide and mostly infects immunocompromised patients, whereas C. gattii occurs mainly in (sub)tropical regions and infects healthy individuals. Anomalous C. neoformans strains were isolated from patients. These strains were found to be monokaryotic, and diploid or aneuploid. Amplified Fragment Length Polymorphism (AFLP) and sequence analyses indicated that AFLP genotypes 2 (C. neoformans) and 4 (C. gattii) were present. The strains were serologically BD. Mating- and serotype-specific PCR reactions showed that the strains were MATa-serotype D/MATalpha-serotype B. This study is the first to describe naturally occurring hybrids between C. neoformans and C. gattii.

Emergence of Cryptococcus gattii in a novel environment provides clues to its incubation period

Cryptococcus gattii emerged in 1999 in a distinct ecologic environment on Vancouver Island, Canada. Estimates of incubation period were derived from an analysis of travelers with discreet exposures to this region. Individual case incubation periods ranged from 2 to 11 months, with a median of 6 to 7 months.

Cryptococcus gattii in wildlife of Vancouver Island, British Columbia, Canada

Although Cryptococcus gattii has emerged as an important pathogen of humans and domestic animals on Vancouver Island, Canada since 1999; its distribution in regional wildlife species is largely unknown. Opportunistic sampling methods were employed to obtain nasal swabs for fungal culture from wild mammal species residing within the coastal Douglas fir biogeoclimatic zone on the southeast coast of the island. Samples were collected from 91 animals representing 14 species. Cryptococcus gattii was isolated from the nasal swabs of two eastern gray squirrels (Sciurus carolinensis) trapped in Duncan, British Columbia. The relative proportion of nasal colonization in wild mammal species is consistent with findings in domestic animals, suggesting that animals may be good indicators of environmental organisms.

A multivariate analysis of soil yeasts isolated from a latitudinal gradient

Yeast isolates from soil samples collected from a latitudinal gradient (>77 degrees S to >64 degrees N) were subjected to multivariate analysis to produce a statistical foundation for observed relationships between habitat characteristics and the distribution of yeast taxa (at various systematic levels) in soil microbial communities. Combinations of temperature, rainfall (highly correlated with net primary productivity), and electrical conductivity (EC) could explain up to ca. 44% of the distribution of the predominant yeast species, rainfall and pH could explain ca. 32% of the distribution of clades in the most common orders (Filobasidiales and Tremellales), whereas vegetation type (trees, forbs, and grass) played the same role for orders. Cryptococcus species with appropriate maximum temperatures for growth predominated in most soils. Cryptococcus species in the Albidus clade of the Filobasidiales predominated in desert soils; Cryptococcus species of other clades in the Filobasidiales and Tremellales predominated in wetter and more-vegetated soils, with Tremellalean species favored in soils of lower pH or higher EC. The predominance of Cryptococcus species in soils has been attributed to their polysaccharide capsules, particularly important when competing with bacteria in arid soils.

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

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

Cryptococcus bestiolae and Cryptococcus dejecticola, two new yeast species isolated from frass of the litchi fruit borer Conopomorpha sinensis Bradley

Two new yeast species, Cryptococcus bestiolae and Cryptococcus dejecticola, were discovered in the frass of the litchi fruit borer Conopomorpha sinensis Bradley. The yeasts utilize inositol, hydrolyze urea, produce starch-like substance, and contain CoQ10. Phylogenetic analyses of D1/D2 26S rDNA and internal transcribed spacer (ITS) sequences indicate that the yeasts are closely related to Bullera dendrophila and an undescribed species of Cryptococcus (strain CBS 8507). The two new species differed from each other by 17 nucleotides in the D1/D2 region and by 68 nucleotides in the ITS region. Cryptococcus bestiolae is a sister species to Cryptococcus sp. CBS 8507, from which it differs by eight nucleotides in the D1/D2 region and 59 nucleotides in the ITS region. Cryptococcus dejecticola and B. dendrophila differed by 13 nucleotides in the D1/D2 and 57 nucleotides in the ITS region. Cryptococcus bestiolae and Cr. dejecticola formed with B. dendrophila a well defined clade consisting of insect associated species. The type strain of Cr. bestiolae is TH3.2.59 (=CBS 10118=NRRL Y-27894), and the type strain of Cr. dejecticola is Litch 17 (=CBS 10117=NRRL Y-27898).

Polysaccharides and phenolic compounds as substrate for yeasts isolated from rotten wood and description of Cryptococcus fagi sp.nov

Pieces of rotten wood collected in the forest were screened for the presence of yeasts. In spring time 3 tree species were sampled, followed by 9 species in summer. Yeast strains were identified by traditional methods. Identifications were confirmed by sequencing of ribosomal DNA in case of doubt. In total 14 yeast species of ascomycetous affiliation and 6 anamorphic basidiomycetous yeasts were isolated and identified. Most species were represented by only one strain, but Candida bertae by two and Trichosporon porosum by six strains, all from different wood samples. Three strains represented novel species, one of which is described as Cryptococcus fagi Middelhoven et Scorzetti. The type strain is CBS 9964 (JCM 13614). All strains were tested for growth on several polysaccharides as sole carbon source. Only some of these polymers supported growth of ascomycetous yeasts. Basidiomycetous yeasts assimilated soluble starch, pullulan, dextran, xylan, polygalacturonate, galactomannan and tannic acid or at least some of these. Cryptococcus podzolicus and T. porosum were the most active in this respect. None of the isolated strains grew on carboxymethyl cellulose, colloidal chitin, arabinogalactan and gum xanthan. Phenolic compounds were assimilated by several strains, belonging to the Trichosporonales and the Microbotryum and Stephanoascus/Blastobotrys clades, but not by members of the Tremellales (Cryptococcus musci excepted) and the Debaryomyces/Lodderomyces clade. Most of the ascomycetes assimilated n-hexadecane.

Evaluation of risk factors for Cryptococcus gattii infection in dogs and cats

OBJECTIVE

To determine risk factors associated with Cryptococcus gattii infection in dogs and cats residing on Vancouver Island in British Columbia, Canada.

DESIGN

Matched case-control study.

ANIMALS

20 dogs and 29 cats with C gattii infection and matched controls.

PROCEDURE

Dogs and cats with a confirmed or probable diagnosis of cryptococcosis resulting from infection with C gattii were enrolled by veterinarians, and owners completed a questionnaire designed to obtain information pertaining to potential risk factors for the disease. Owners of matched control animals were also interviewed. Odds ratios and 95% confidence intervals or paired t tests were calculated to determine significant associations.

RESULTS

Animals were enrolled during 2 noncontiguous periods in August 2001 to February 2002 (8 dogs and 9 cats enrolled) and May to December 2003 (12 dogs and 20 cats enrolled). Risk factors significantly associated with development of cryptococcosis included residing within 10 km of a logging site or other area of commercial soil disturbance, above-average level of activity of the animal, travelling of the animal on Vancouver Island, hunting by the animal, and owners hiking or visiting a botanic garden.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that dogs and cats that were active or that lived near a site of commercial environmental disturbance had a significantly increased risk of developing C gattii infection. Veterinarians should communicate these risks to owners in context because cryptococcosis was an uncommon disease in this population.

Metal tolerance of yeasts isolated from water, soil and plant environments

The tolerance of seventy yeast strains belonging to 15 species, isolated from water and soil environments as well as from tree leaves, to four heavy metals--copper, zinc, nickel and cadmium were studied. We have found that the interspecific and intraspecific variations in metal tolerance among studied strains were considerable. The highest interspecific variations were observed toward copper and cadmium. The strains of the species Sporobolomyces salmonicolor, Cryptococcus albidus, Cystofilobasidium capitatum, Saccharomyces cerevisiae, and Candida maltosa belonged to the most sensitive ones. In general ascomycetous yeasts were more tolerant to heavy metals than basidiomycetous ones. The differences among strains that came from various natural sources were also found. The most sensitive yeast population originated from untilled soil whereas the most tolerant population was isolated from tree leaves.

Follow-up study of dogs and cats with asymptomatic Cryptococcus gattii infection or nasal colonization

The pathogenesis of Cryptococcus spp. infection following nasal colonization is unclear. This article reports follow-up data on a cohort of seven cats and five dogs identified in a previous study as sub-clinically infected with Cryptococcus spp. or colonized by C. gattii. Two cats progressed to clinical disease within four to six months of initial detection of antigenemia and nasal cavity colonization. The ten other animals remained asymptomatic but many were repeatedly positive on cryptococcal antigen testing or nasal fungal culture suggesting protracted infection or colonization. The results indicate that asymptomatically infected animals may clear the organism, remain sub-clinically infected or progress to clinical disease. Factors influencing the transition from exposure to disease require further investigation.

Cryptococcus gattii in AIDS patients, southern California

A molecular analysis of pheromone genes showed a notable prevalence of Cryptococcus gattii isolates from AIDS patients in southern California.

Cryptococcus isolates from AIDS patients in southern California were characterized by molecular analyses. Pheromone MFα1 and MFa1 gene fragments were polymerase chain reaction–amplified with fluorescently labeled primers and analyzed by capillary electrophoresis (CE) on DNA analyzer. CE–fragment-length analyses (CE-FLAs) and CE–single-strand conformation polymorphisms (CE-SSCPs) were used to determine Cryptococcus gattii (Cg), C. neoformans (Cn) varieties neoformans (CnVN) and grubii (CnVG), mating types, and hybrids. Corroborative tests carried out in parallel included growth on specialized media and serotyping with a commercial kit. All 276 clinical strains tested as haploid MATα by CE-FLA. CE-SSCP analyses of MFα1 showed 219 (79.3%) CnVG, 23 (8.3%) CnVN, and 34 (12.3%) Cg isolates. CE-FLA and CE-SSCP are promising tools for high-throughput screening of Cryptococcus isolates. The high prevalence of Cg was noteworthy, in view of its sporadic reports from AIDS patients in North America and its recent emergence as a primary pathogen on Vancouver Island, Canada.

Sub-clinical infection and asymptomatic carriage of Cryptococcus gattii in dogs and cats during an outbreak of cryptococcosis

Since 1999, Cryptococcus gattii has emerged as an important pathogen of humans and animals in British Columbia, Canada. Nasal swabs and serum samples were collected from dogs and cats residing within the Coastal Douglas Fir biogeoclimatic zone on Vancouver Island, where clinical cases have been reported. Deep and superficial nasal fungal cultures of 280 dogs and 94 cats identified four (4.3%) cats and three (1.1%) dogs with C. gattii serotype B in their nasal cavity. Serum samples collected from 266 dogs and 84 cats identified six (7.1%) cats and two (0.8%) dogs with a positive cryptococcal antigen titer. Overall cats were 4.4 times more likely than dogs to be positive on one or both tests. Identification of sub-clinical infection and nasal colonization is an important step in the characterization of the outbreak of clinical cryptococcosis on Vancouver Island.

Cryptococcus gattii: in vitro susceptibility to the new antifungal albaconazole versus fluconazole and voriconazole

Minimal inhibitory concentrations (MIC) and minimal fungicidal activity of albaconazole, voriconazole and fluconazole against 55 strains of Cryptococcus gattii, clinically or environmentally isolated in Spain and some Latin American countries, were assessed. By means of the microbroth method (National Committee for Clinical Laboratory Standards; document M27-A2), the geometric mean value for fluconazole was 5.01 microg/ml; however, MIC for 12.7% of isolates ranged from 16 to 32 microg/ml, suggesting increased resistance against fluconazole. Geometric mean values of 0.02 and 0.03 microg/ml for albaconazole and voriconazole, respectively, were found, indicating not only a higher susceptibility to these new azoles but also a better performance of albaconazole (P = 0.003). Minimal fungicidal concentrations were also very low for albaconazole and voriconazole (P<0.001; geometric mean values of 0.023 microg/ml and 0.07 microg/ml, respectively). Both azoles may be good alternatives for the treatment of C. gattii cryptococcosis.

Recrudescent cryptococcosis, caused byCryptococcus gattii(molecular type VGII),over a 13-year period in a Birman cat

A 17-year-old desexed male Birman cat presented with a fleshy mass protruding from the left ear canal. A culture from the mass revealed a heavy growth of Cryptococcus gattii (molecular type VGII, serotype B). The lesion resolved with antifungal therapy over 8 weeks. Itraconazole was continued indefinitely due to persistent high serum cryptococcal antigen titres. The cat was euthanased 12 months later due to the acute development of hindlimb ataxia and collapse which may or may not have been attributable to cryptococcosis. This cat had first presented when 4 years of age with a 3-week history of inappetance, sneezing and serous nasal discharge. Culture of swabs from both nostrils were positive for C. gattii (VGII). Fluconazole therapy produced steady improvement over a 6 month period, at which time therapy was discontinued. The cat presented 9 months later for sneezing, again with a positive culture of C. gattii from the nasal cavity. Antifungal therapy was continued for 8 months, after which time cultures were negative and symptoms resolved. Three episodes of cryptococcosis in a cat over a 13-year period were thus documented. Importantly, the two C. gattii isolates, obtained 13 years apart, were identical using DNA fingerprinting and random amplification of polymorphic DNA (RAPD) analysis.

A new name for Torula glutinosa in Heteroconium

Torula glutinosa, a sooty mold on living leaves and stems of Eriodictyon spp. from California is illustrated and described. It shares, with the type species of Heteroconium, H. citharexyli, acropetal conidiogenesis of chains of conidia of variable length and acropetal transseptation. An unnamed synanamorph is recognized and described.

Cryptococcus silvicola nov. sp. from nature reserves of Russia and Portugal

Nitrate-positive strains of a filobasidiaceous anamorphic yeast related to Cryptococcus cylindricus were isolated from forest litter in a Russian nature reserve and from a lichen in Portuguese one. Mycocinotyping and rDNA sequence analysis revealed that the strains represent a novel species, for which the name Cryptococcus silvicola (type strain VKM Y-2939=CBS 10099) is proposed.

Isolation of Cryptococcus species including C. neoformans from cloaca of pigeons

Upper digestive tract of the pigeon (Columba livia) is well known as a reservoir for different species of Cryptococcus, but lower portions are not so frequently studied. In the present study, we tested on selective media a total of 331 pigeon cloacal swabs; Cryptococcus spp. were recovered from 26 (7.85%). Cryptococcus uniguttulatus was isolated from 11 samples (3.32%), C. laurentii from six (1.81%), C. neoformans var. neoformans from six (1.81%) and C. albidus from three of them (0.91%). The results show the importance of pigeon in the cryptococcosis epidemiology as reservoir and carrier for C. neoformans var. neoformans, but also for other Cryptococcus species of increasing clinical interest.

Invasive Cryptococcus laurentii disease in a nine-year-old boy with X-linked hyper-immunoglobulin M syndrome

We report a 9-year-old boy with X-linked hyper-immunoglobulin M syndrome and invasive Cryptococcus laurentii infection identified on the basis of morphologic and biochemical characteristics and serologic tests. Fluconazole treatment resulted in complete recovery. We believe that C. laurentii should be included in the differential diagnosis of opportunistic fungal infections in patients with primary T cell immunodeficiencies.

[Isolation of Cryptococcus gattii serotype B from detritus of Eucalyptus trees in Colombia]

INTRODUCTION

Cryptococcus gattii serotype B has been associated with several species of trees in tropical and subtropical regions. Serotype B has been found to be the second most frequently isolated from patients in Colombia, but it has not been isolated from the environment. Therefore, a study was designed to sample plant material from a forest in the province of Cundinamarca, with the aim of establishing the presence and distribution of the C. neoformans complex, specially serotype B. In addition, isolates were evaluated for several phenotypic characteristics associated with virulence.

METHODOLOGY

During February and March, 2003, 4 separate sample collections were made. One hundred sixty-seven samples were collected from detritus of eucalyptus and 28 samples from other species of trees. All were processed using the conventional procedure and plated on selective media. The following parameters were measured: cellular and capsular sizes in the filtrates, growth at 37 degrees C, virulence in a mouse animal model system, and mating type as detected by PCR.

RESULTS

Cryptococcus gattii serotype B was isolated from 46 eucalyptus samples (27.5%). The cellular size in the filtrates ranged from 3.10 to 4.15 microm and the capsular size from 0.30 and 0.46 microm. The 46 isolates grew at 37 degrees C, but none of them caused the death in the animals during 70-day observation period. All isolates were of mating type a.

CONCLUSIONS

This constitutes the first report of the isolation of serotype B, mating type a, from eucalyptus detritus in Colombia.

Cryptococcal antigen test revisited: significance for cryptococcal meningitis therapy monitoring in a tertiary chinese hospital

For a total of 29 non-human immunodeficiency virus 1 cryptococcal meningitis cases, titer changes in the latex agglutination test before and after therapy were reviewed along with clinical manifestations, laboratory findings, and therapy regimens. The cryptococcal antigen titer decreased for every case after therapy and was correlated to fungal clearance as defined by fungus smear and/or culture. However, cryptococcal antigen can remain at low titers for long periods of time after therapy, even when fungus smears and/or cultures become negative.

Prevalence of clinical isolates of Cryptococcus gattii serotype C among patients with AIDS in Sub-Saharan Africa

Cryptococcus gattii is a group of exogenous, neurotropic yeasts that possess the capsular serotype B or C. Isolates of serotype C are extremely rare and, until recently, were known to infect only immunocompetent individuals. We genotyped 176 isolates of Cryptococcus from patients in sub-Saharan Africa who had AIDS; 22 (13.7%) of 161 isolates from Botswana and 2 (13.3%) of 15 isolates from Malawi were C. gattii serotype C strains. All of these serotype C strains belong to the rare VGIV genotype, possess the MAT alpha mating-type allele, and exhibit little genetic diversity.

Baseline correlation and comparative kinetics of cerebrospinal fluid colony-forming unit counts and antigen titers in cryptococcal meningitis

Cerebrospinal fluid (CSF) cryptococcal colony-forming unit counts and CSF cryptococcal antigen titers serve as alternative measures of organism load in cryptococcal meningitis. For these measures, we correlated baseline values and rates of decline during the first 2 weeks of therapy in 68 human immunodeficiency virus--seropositive patients with cryptococcal meningitis. At baseline, there was a strong correlation between CSF cryptococcal colony-forming unit counts and CSF cryptococcal antigen titers. During the first 2 weeks of therapy, CSF cryptococcal colony-forming unit counts decreased by >5 logs, and CSF cryptococcal antigen titers decreased by 1.5 dilutions. In individual patients, there was no correlation between the rate of decline in CSF cryptococcal colony-forming unit counts and that in CSF cryptococcal antigen titers.

Follow-up of epidemiological data of cryptococcosis in Austria, Germany and Switzerland with special focus on the characterization of clinical isolates

The present survey in Austria, Germany and Switzerland continued the survey of cryptococcosis set up by the European Confederation of Medical Mycology (ECMM) in 1997. From 2000 to 2003 77 cases have been reported. An HIV infection is still the most important risk factor (68%). Young HIV+ women from ASIA contributed to the increase of cryptococcosis in females. A total of 129 clinical isolates of both surveys were genotyped by PCR fingerprinting to study the prevalence of different genotypes. The prevalence of Cryptococcus neoformans var. grubii (serotype A) with the genotypes VNA1 and VNA2 was higher in Germany and Austria (74.5%) than in Switzerland (52%), while in Switzerland the Cr. neoformans hybrids AD (26%) and Cr. neoformans var. neoformans (serotype D) (22%) were more prevalent compared with Germany and Austria (8 and 17.5% respectively). Cryptococcus gattii isolates were studied by FT-IR spectroscopy. DNA in the ITS region was sequenced to get further information about Cr. neoformans serotype AD strains and about the geographical origin of the Cr. gattii isolates. The ITS sequence of the serotype AD isolates of the genotypes VNAD1, VNAD2 and VNAD4 is usually identical to serotype A or serotype D respectively. In the three isolates of the genotype VNAD3 a genotype-specific sequence pattern was detected. Two autochthonous infections due to Cr. gattii could indicate that the genotype VGIV with the ITS type 'Asia 2' might be endemic in Europe.