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PubMedDate not supplied

[Identification of varieties of Cryptococcus neoformans by the use of culture media].

Ten Cryptococcus neoformans strains of human origin were studied in order to know their variety by using 2 different culture mediums: creatinine-bromothymol-blue-dextrose and glycine-cycloheximide-phenol red. The results obtained in the two mediums were not totally coincidental. The possible causes and the specificity of these mediums for identifying C. neoformans varieties are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Phospholipase activity in Cryptococcus neoformans: a new virulence factor?

Fifty isolates of Cryptococcus neoformans were examined for extracellular phospholipase production after inoculation onto egg yolk agar; 49 produced a pericolonial precipitate indicative of phospholipase activity. Phospholipase B (PLB), lysophospholipase, and lysophospholipase-transacylase activities were identified by radiometric analysis in supernatants from 4 clinical isolates. The ratio of colony diameter to colony plus precipitate on agar (Pz) correlated with PLB activity. Phospholipase production was similar in 12 environmental and 13 clinical isolates of C. neoformans var. gattii. Environmental strains of C. neoformans var. neoformans (n = 8) produced more phospholipase at 72 h than did 17 clinical isolates (mean Pz, 0.57 vs. 0.72; P < .01); however, Pz values were similar at 96 h. Quantitation of cryptococci in the lungs and brains of BALB/c mice inoculated intravenously with 4 strains expressing high, intermediate, or low phospholipase activity revealed a correlation between phospholipase activity and virulence. Phospholipases secreted by C. neoformans may be implicated in virulence.

Acyltransferases↗
PubMed1978

A rapid pigmentation test for identification of Cryptococcus neoformans.

A rapid pigmentation test for identification of Cryptococcus neoformans is described. The method is based on the formation of a characteristic, mouse-grey to violaceous-black pigment when shake cultures of C. neoformans in a phosphate-buffered, l-DOPA - ferric citrate medium are incubated at 37 C for one hour.

Catechol Oxidase↗
PubMed2025

A method for authenticating the fidelity of Cryptococcus neoformans knockout collections.

Gene knockout (KO) strain collections are important tools for discovery in microbiology. Cryptococcus neoformans, a human fungal pathogen, has an available genome-wide gene deletion collection that is widely used by the research community. We uncovered mix-ups in the assembly of the commercially available C. neoformans deletion collection of ~4,700 unique strains acquired by our laboratory. Evidence supporting a mix-up includes RNAseq analysis that identified transcripts for the gene listed as the KO. The mystery was soon solved as this same KO strain lacked RNA transcripts for a different KO strain gene found in the same plate position in an earlier partial KO collection, suggesting a plate swap between two KO collections. Therefore, we developed a quick PCR assay to distinguish the two KO collections based on the size differences between their nourseothricin (NAT)-resistance cassettes, confirmed by genome sequencing. Here, we report that nine of the first 15 plates of the 42-plate our KN99&#x251; KO collection had been replaced with the corresponding plates from an earlier partial KO collection. We provide additional evidence that the remaining plates are correct, and the simple authentication method presented here serves as a quick check to identify similar mix-ups in the KO collections.IMPORTANCEGene KO strain collections are important tools for discovery in microbiology. The human fungal pathogen Cryptococcus neoformans has an available genome-wide deletion collection that is widely used by the research community. Here, we report that our KN99&#x251; collection is comprised of mixed plates from two independent KO libraries and present a simple authentication method that other investigators can use to distinguish the identities of these KO collections. Above all, this article serves as a reminder to users of the 2015 KO library collection to screen the plates before undertaking large phenotyping experiments.

Cryptococcus neoformans↗
PubMed1990

Natural habitat of Cryptococcus neoformans var. gattii.

Environmental isolations have established that Cryptococcus neoformans var. gattii appears to have a specific ecological association with Eucalyptus camaldulensis. So far, we have isolated C. neoformans var. gattii on 35 separate occasions, all from samples associated with E. camaldulensis. The global distribution of E. camaldulensis appears to correspond to the epidemiologic distribution of cryptococcosis caused by C. neoformans var. gattii. No other environmental source for the fungus has yet been detected, and no other eucalypt has the distribution pattern corresponding to reported cases caused by this fungus. These findings may provided an explanation for the high incidence of infections caused by C. neoformans var. gattii in Australian aborigines living in the Northern Territory and for its low worldwide incidence in acquired immunodeficiency syndrome patients.

Australia↗
PubMed1966

Medium for selective isolation of Cryptococcus neoformans.

A medium has been developed that permits the selective recovery of Cryptococcus neoformans from heavily contaminated materials. It employs creatinine as a nitrogen source, diphenyl (C(6)H(5)C(6)H(5)) and chloramphenicol as mold and bacterial inhibitors, and Guizotia abyssinica seed extract as a specific color marker. The medium has proved to be effective in the direct isolation of Cryptococcus neoformans from pigeon nests and from the air.

Biphenyl Compounds↗
PubMed1991

Normally saprobic cryptococci isolated from Cryptococcus neoformans infections.

We report two cases in which Cryptococcus laurentii was isolated from surgically resected pulmonary lesions but the cryptococcal cells is tissue reacted positively with a specific fluorescent antibody (FA) conjugate for Cryptococcus neoformans. Both patients had no apparent host defense defects. In both cases, multiple cryptococcal isolates were obtained from tissue, and yeastlike cells consistent with C. neoformans were seen in direct histology. The isolates were identified by assimilation patterns and standard procedures including phenoloxidase reactions. Since C. laurentii was consistently isolated by using stringent procedures, it was considered unlikely that the fungus represented surgical or laboratory contamination. Its presence may be the result of dual infection not detected by FA, but other possible explanations exist. The results show the value of the FA test in diagnostic mycology and call into question previous reports of cryptococci other than C. neoformans as agents of infection.

Adult↗
PubMed2003

Anasarca caused by Cryptococcus neoformans after heart transplantation.

Cryptococcosis is an opportunistic infection caused by the yeast-like fungus Cryptococcus neoformans. The infection predominantly strikes patients with cell-mediated immunodeficiency, that is, patients with organ transplants, leukemia, lymphoma, AIDS, and those receiving steroids or immunosuppressants. We describe a patient with skin lesions and anasarca secondary to intestinal infection from Cryptococcus neoformans after heart transplantation. We based diagnosis on histologic examination of the cutaneous lesions and of the duodenal mucosa. This case demonstrates that in immunosuppressed patients with anasarca of unknown origin, a diagnosis of intestinal opportunistic infection also should be considered.

Cryptococcosis↗
PubMed1993

Multilocus enzyme typing of Cryptococcus neoformans.

Multilocus enzyme electrophoresis was adapted for subtyping Cryptococcus neoformans. The two cryptococcal varieties were clearly distinguishable. Isolates of the C. neoformans var. neoformans were sorted according to serotype and were sorted into four to five subtypes within each serotype. Nearly no two isolates of the C. neoformans var. gattii displayed the same enzyme electrophoretic type. This method may be a useful adjunct to current methods for classification and epidemiologic studies of cryptococci.

Cryptococcus neoformans↗
PubMed1998

[The identification of Cryptococcus neoformans var. neoformans in Cuban clinical isolates].

50 strains of Cryptococcus neoformans of clinical origin were studied by using the canavanine-glycine-bromothymol blue (CGB) medium. 56% of the strains were isolated from AIDS patients, and 16% belonged to patients with kidney transplantation. 90% of the samples were obtained from the samples of cerebrospinal fluid, which corresponded to the classical form of presentation of cryptococcosis. All the strains were identified as C. neoformans var. neoformans, coinciding with previous reports made in Cuba. Knowing the varieties of C. neoformans, inferences can be drawn on the epidemiology, clinics and response to the treatment of cryptococcosis.

Acquired Immunodeficiency Syndrome↗
PubMed2004

The first isolation of Cryptococcus neoformans from Eucalyptus trees in South Aegean and Mediterranean Regions of Anatolia in Turkey despite Taurus Mountains alkalinity.

Eucalyptus trees are widespread in subtropical parts of Turkey that have alkaline environments due to the soil structure of Taurus Mountains. In this study, the existence of Cryptococcus neoformans in eucalyptus trees in the South Aegean and Mediterranean Regions of Anatolia, Turkey, was screened between March 1998 and September 2002. Only one strain of Cryptococcus neoformans var. grubii (Serotype A) was isolated from 1175 eucalyptus samples including debris and flowers in culture by Guizotia abyssinica agar. The environmental niche of the isolate was Eucalyptus camaldulensis Dehn in the Gokova Region, in the western part of the Taurus Mountains. In this study, the existence of Cryptococcus neoformans was shown in the eucalyptus flora of Turkey despite the alkaline soil condition.

Animals↗
PubMed2005

Radiological studies reveal radial differences in the architecture of the polysaccharide capsule of Cryptococcus neoformans.

The polysaccharide capsule of the pathogenic fungus Cryptococcus neoformans is an important virulence factor, but relatively little is known about its architecture. We applied a combination of radiological, chemical, and serological methods to investigate the structure of this polysaccharide capsule. Exposure of C. neoformans cells to gamma radiation, dimethyl sulfoxide, or radiolabeled monoclonal antibody removed a significant part of the capsule. Short intervals of gamma irradiation removed the outer portion of the cryptococcal capsule without killing cells, which could subsequently repair their capsules. Survival analysis of irradiated wild-type, acapsular mutant, and complemented mutant strains demonstrated that the capsule contributed to radioprotection and had a linear attenuation coefficient higher than that of lead. The capsule portions remaining after dimethyl sulfoxide or gamma radiation treatment were comparable in size, 65 to 66 microm3, and retained immunoreactivity for a monoclonal antibody to glucuronoxylomannan. Simultaneous or sequential treatment of the cells with dimethyl sulfoxide and radiation removed the remaining capsule so that it was not visible by light microscopy. The capsule could be protected against radiation by either of the free radical scavengers ascorbic acid and sorbitol. Sugar composition analysis of polysaccharide removed from the outer and inner parts of the capsule revealed significant differences in glucuronic acid and xylose molar ratios, implying differences in the chemical structure of the constituent polysaccharides. Our results provide compelling evidence for the existence of two zones in the C. neoformans capsule that differ in susceptibility to dimethyl sulfoxide and radiation and, possibly, in packing and composition.

Antibodies, Monoclonal↗
PubMed2005

[Environmental distribution of Cryptococcus neoformans in the department of Cundinamarca-Colombia].

Cryptococcus neoformans is an opportunistic fungal pathogen that could cause infection in patients with immunodeficiency and healthy patients. The AIDS epidemic has shown the importance of studying the ecology and epidemiology of this fungus. The aim of this investigation was to determine if there was a relationship between the environmental distribution of the different varieties of C. neoformans and the climate zones in two transects located in department of Cundinamarca, in Colombia. For the isolation and identification of the yeast, conventional phenotypic methods were used and it was determined the population density (CFU/g of sample) and which was the variety of greater prevalence in each altitudinal rank. A total of 765 samples, from 26 municipalities were collected; of these 146 corresponded to pigeon droppings (Columba livia), 437 to Eucalyptus detritus (Eucalyptus camaldulensis and related species) and 182 to detritus of almond trees (Terminalia cattapa). C. neoformans was isolated from 46% of the studied municipalities, in both transects and the climate zones: warm, temperate and cold. The results indicated that the greater frequency of positive isolations came from the last climate zone (cold). The population density in pigeon excrements oscillated between 50 and 9.2 x 1,000,000, in eucalyptus between 500 and 10 x 1,000,000 and in almond trees was 50 CFU/g. Of 100,000 positive isolations 31% were serotype A, 59% serotype B and 10% serotype C; 96% of the isolates grew to 37 degrees C and all showed capsule. In conclusion, C. neoformans prevails in the three habitats studied but it showed a predilection for the cold thermal floor; the population densities did not allow defining a standard pattern of occurrence.

Altitude↗
PubMed2002

[Rapid extraction of MtDNA from Cryptococcus neoformans and examined by electronic microscopy].

Cryptococcus neoformans may be grown to the exponential phase,are broken by a combination of NovoZym234 and mechanical means,and mitochondrial DNA was extracted from DNaseI-treated mitochondrial preparation by differential centrifugation. Three pellets, including yeast cell, protoplasts, mitochondrial, were examined by transmission electronic microscopy. The resulting mtDNA is sufficiently pure for restriction endonucleases analysis and PCR in further studying. A rapid and effective method for the preparation of the mtDNA of C.neoformans was established.

English Abstract↗
PubMed2004

Antibody to Cryptococcus neoformans glucuronoxylomannan inhibits the release of capsular antigen.

Cryptococcus neoformans releases capsular polysaccharide in the supernatant of liquid cultures and in tissues. Significantly less glucuronoxylomannan (GXM) was released by C. neoformans in the presence of capsule-binding monoclonal antibody (MAb). MAb-mediated inhibition of GXM release may be another mechanism by which humoral immunity can mediate protection against this pathogen.

Antibodies, Fungal↗
PubMed1987

Growth inhibition of Cryptococcus neoformans by human alveolar macrophages.

Macrophage cytotoxicity for Cryptococcus neoformans was investigated by culturing human alveolar macrophage (AM) with a thin-capsuled clone of C. neoformans in a polypropylene culture tube assay system. Yeast replication was quantitated by electronic particle counting after detergent lysis of AM and viability by quantitative plate counts. Under appropriate conditions, fungal replication was inhibited in the presence of human AM. This effect persisted over the 48-h time course that was evaluated. During this period, organisms in medium alone proliferated rapidly, doubling their number every 4 h. Human AM did not require endotoxin, fetal calf serum, or specific rabbit anticryptococcal antibody for fungistasis. Under these conditions, microscopic evaluation of a cytocentrifuge preparation of AM-yeast cocultures, stained by a modified Giemsa technique, revealed all the fungi to be extracellular. In the presence of 10% fresh human serum, AM phagocytized C. neoformans and exhibited fungicidal activity. Tumor necrosis factor did not affect the replication rate of the yeast. These findings suggest that there may be at least 2 mechanisms by which human AM protect against C. neoformans. One is serum-independent and extracellular and results in fungistasis, and the other is dependent on a serum factor and leads to intracellular inhibition of growth and possibly killing of the organism.

Blood↗
PubMed1988

In vitro susceptibility of Cryptococcus neoformans isolates from patients with acquired immunodeficiency syndrome.

Cryptococcus neoformans strains from 26 individual patients with acquired immunodeficiency syndrome (AIDS) and three isolates from patients without AIDS were tested for their susceptibility to amphotericin B, flucytosine, ketoconazole, and miconazole nitrate. Ninety percent of the C neoformans isolates from patients with AIDS were inhibited by drug concentrations within achievable serum levels. The minimum fungicidal concentration of the four tested antifungal agents, however, exceeded obtainable cerebrospinal fluid levels.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Molecular and genetic analysis of the Cryptococcus neoformans MET3 gene and a met3 mutant.

The Cryptococcus neoformans MET3 cDNA (encoding ATP sulfurylase) was cloned by complementation of the corresponding met3 mutation in Saccharomyces cerevisiae. Sequence analysis showed high similarity between the deduced amino acid sequence of the C. neoformans Met3p and other fungal ATP sulfurylases. A C. neoformans met3 mutant was made by targeted insertional mutagenesis, which had the expected auxotrophic phenotype, and reconstituted the met3 mutant to Met(+). In vitro, the C. neoformans met3 mutant had a substantial defect in melanin formation, significantly reduced growth rate, and greatly increased thermotolerance. In the murine inhalation infection model, the met3 mutant was avirulent and was deficient in its ability to survive in mice. It is concluded that, in contrast to the yeast form of Histoplasma capsulatum, in C. neoformans the sulfate-assimilation arm of the methionine biosynthetic pathway plays an important role in vitro, even in the presence of abundant exogenous methionine, and is critical for virulence, and indeed for survival, in vivo.

Animals↗