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PubMed1987

Failure of the Bactec 460 radiometer to detect Cryptococcus neoformans fungemia in an AIDS patient.

Cryptococcus neoformans fungemia occurred in a patient with the acquired immunodeficiency syndrome (AIDS). The BACTEC 460 radiometer failed to detect Cryptococcus neoformans in eight aerobic BACTEC 6B culture bottles inoculated with the patient's blood. The diagnosis of cryptococcemia was established by terminal (seven-day) subculturing of 6B broth to chocolate agar, which was positive for all eight radiometrically negative blood culture bottles. It appears that radiometric measurement is not optimal for the laboratory detection of cryptococcal fungemia.

Acquired Immunodeficiency Syndrome↗

PubMed1975

Combined activity of amphotericin B and 5-fluorocytosine against Cryptococcus neoformans in vitro and in vivo in mice.

The in vitro and in vivo activities of amphotericin B and 5-fluorocytosine (5-FC) alone and in combination were studied to determine possible drug interactions against two strains of Cryptococcus neoformans, one sensitive to 5-FC and one resistant to 5-FC. In vitro tube dilution studies demonstrated only additive effects with the 5-FC-sensitive organism but antagonism with eth 5-FC-resistant organism. A mouse model of cryptococcal meningitis allowed comparative drug trails in a new model for the detection of drug interactions. Drug combinations were no more effective against meningitis caused by the 5-FC-sensitive organism than the additive effects of the individual drugs. However, meningitis caused by the 5-FC-resistant Cryptococcus responded less to drug combinations than to either drug alone. Serum levels of amphotericin B and 5-FC were comparable in all groups. No evidence of toxicity from the drug combinations was found. No inhibition of development of resistance to 5-FC by the combination with amphotericin B was detected.

Amphotericin B↗

PubMed2006

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.

Cryptococcosis↗

PubMed1986

Canavanine resistance in Cryptococcus neoformans.

All of the isolates of Cryptococcus neoformans var. gattii which we tested were resistant to greater than or equal to 3.5 mM canavanine. All of the serotype D isolates and 28% of the serotype A isolates of C. neoformans var. neoformans tested were susceptible to less than or equal to 18 microM canavanine, whereas the remaining 72% of the serotype A isolates were as resistant as the C. neoformans gattii isolates. In the naturally resistant isolates, the mechanism of resistance appeared to be decomposition of canavanine to a nontoxic product. However, in a resistant mutant derived from a naturally susceptible isolate, the mechanism of resistance was an impaired uptake system for canavanine. The toxic effect of canavanine in Cryptococcus results from the incorporation of canavanine into the protein component that is essential for the synthesis of proteins and RNAs.

Arginase↗

PubMed2005

Clinical and environmental isolates of Cryptococcus gattii from Australia that retain sexual fecundity.

Cryptococcus gattii is a primary pathogenic yeast that causes disease in both animals and humans. It is closely related to Cryptococcus neoformans and diverged from a common ancestor approximately 40 million years ago. While C. gattii has a characterized sexual cycle dependent upon a dimorphic region of the genome known as the MAT locus, mating has rarely been observed in this species. In this study, we identify for the first time clinical (both human and veterinary) and environmental isolates from Australia that retain sexual fecundity. A collection of 120 isolates from a variety of geographic locations was analyzed for molecular type, mating type, and the ability to develop mating structures when cocultured with fertile tester strains. Nine isolates produced dikaryotic filaments with paired nuclei, fused clamp connections, and basidiospores. DNA sequence analysis of three genes (URA5, the MATalpha-specific SXI1alpha gene, and the MATa-specific SXI2a gene) revealed little or no variability in URA5 and SXI2a, respectively. However across the 108 MATalpha strains sequenced, the SXI1alpha gene was found to exist as 11 different alleles. Phylogenetic analysis found most variation to occur in the more fertile genotypes. Although some lineages of Australian C. gattii have retained the ability to mate, the majority of isolates were sterile, suggesting that asexuality is the dominant mode of propagation in these populations.

Alleles↗

PubMed1984

Binding of cryptococcal polysaccharide to Cryptococcus neoformans.

Radioiodinated cryptococcal polysaccharide was used to study binding of the soluble polysaccharide to encapsulated and non-encapsulated cryptoccoci. Binding of polysaccharide to non-encapsulated cryptococci occurred rapidly over a 30-min period and was largely complete after 2 h. Bound, labeled polysaccharide was slowly eluted from Cryptococcus neoformans after the addition of unlabeled polysaccharide, indicating reversibility of binding. Non-encapsulated cryptococci bound polysaccharide in two ways. Specific binding to the yeast was saturable by ca. 82 ng of polysaccharide per 10(6) yeast cells. Nonspecific binding also occurred which was not saturable under the conditions used in our experiments. Phagocytosis of the non-encapsulated yeast strain was inhibited when the specific binding was ca. 50% saturated. Binding of polysaccharide to an encapsulated strain showed nonspecific, nonsaturable binding, but little specific binding occurred. Presumably the specific binding sites were saturated in the encapsulated strain. Polysaccharides obtained from a hypocapsular mutant (A61) and a normally encapsulated strain competed effectively with labeled serotype D polysaccharide for binding sites on non-encapsulated cryptococci and had identical phagocytosis-inhibiting properties. Similarly, polysaccharides from all four cryptococcal serotypes competed effectively with labeled serotype D polysaccharide for binding sites on the non-encapsulated strain, and all four polysaccharides inhibited phagocytosis of non-encapsulated Cryptococcus neoformans. Unmodified, de-O-acetylated, carboxyl-reduced, periodate-oxidized and reduced (polyalcohol), and Smith-degraded polysaccharides competed with labeled polysaccharide for binding sites on the cell. The unmodified, de-O-acetylated and carboxyl-reduced polysaccharides inhibited phagocytosis of non-encapsulated cells, but the polyalcohol and Smith product were unable to inhibit phagocytosis.

Animals↗

PubMed1974

Skin testing of guinea pigs and footpad testing of mice with a new antigen for detecting delayed hypersensitivity to Cryptococcus neoformans.

This study was undertaken to evaluate the potential of a cryptococcal culture filtrate antigen, cryptococcin C184, for detecting delayed hypersensitivity in Cryptococcus neoformans-injected animals. The antigen was tested on guinea pigs which had received saline or C. neoformans and on animals sensitized to Histoplasma capsulatum, Blastomyces dermatitidis, Candida albicans, or Sporothrix schenckii. A delayed-type hypersensitivity response was elicited by cryptococcin C184 in C. neoformans-injected guinea pigs, whereas no indurations or erythemas were seen at 48 h after skin testing of saline controls or heterologously sensitized guinea pigs. Besides being specific for Cryptococcus, the antigen showed a high degree of sensitivity and was reproducible. Footpad tests were conducted with the antigen on mice which had previously received either 10(5) viable C. neoformans cells or saline. Delayed hypersensitivity was indicated in the C. neoformans-injected mice by the increase in thickness of antigen-injected footpads when compared with the saline-injected footpads. In control mice, antigen- and saline-injected footpads were comparable in thickness 24 h after injection. Mice sensitized to B. dermatitidis were footpad tested with C184, and no cross-reactivity was demonstrated.

Agglutination Tests↗

PubMed1961

Some factors which affect the initiation of growth of Cryptococcus neoformans.

Howard, Dexter H. (University of California, Los Angeles). Some factors which affect the initiation of growth of Cryptococcus neoformans. J. Bacteriol. 82:430-435. 1961.-The observation that a strain of Cryptococcus neoformans failed to grow in a medium containing normal human serum led to an investigation of some of the physiological factors controlling initiation of growth by this fungus. The data presented show that the growth of C. neoformans is markedly inhibited in media with initial pH values slightly above neutrality. The growth of four strains of the fungus was completely suppressed in peptone broth at pH values above 8. The growth of two strains was partially inhibited at a pH of 7.3. Two other strains grew well at 7.3, but were partially inhibited at pH 7.5. The growth in media at pH values which partially inhibited multiplication was granular in appearance. Microscopically the granules were composed of clumps of yeast cells. The possibility is suggested that pH may exert a portion of its effect on the growth of C. neoformans by influencing those factors which affect the stability of the cells in suspension. At a temperature of 25 C, growth of the fungus was initiated in media with a pH which suppressed growth at a temperature of 37 C. Under the experimental conditions employed in these studies, proteose peptone no. 3 (Difco) serves as both a carbon and a nitrogen source. However, glucose, which is assimilated by C. neoformans in contrast to lactose, permitted the growth of the fungus at pH values which suppressed growth in the absence of the sugar. Since weakly buffered media, containing filtered, normal human serum, have an alkaline reaction higher than that shown to suppress the growth of C. neoformans, it was concluded that this factor was primarily responsible for the failure of the fungus to reproduce in tissue culture media. However, it is also possible to show that even under optimal pH conditions normal human serum exerts an anticryptococcal effect. This activity of human serum was relatively heat-stable and was expressed only in high concentrations of serum. Serum adsorbed with viable cells of C. neoformans also inhibited the growth of the fungus, but a partially purified globulin fraction of serum was not inhibitory. The data are discussed in relation to the work of other investigators.

Cryptococcus↗

PubMed1964

INFECTION OF WHITE SWISS MICE WITH AIRBORNE CRYPTOCOCCUS NEOFORMANS.

Smith, C. D. (Communicable Disease Center, Kansas City, Kansas), R. Ritter, H. W. Larsh, and M. L. Furcolow. Infection of white Swiss mice with airborne Cryptococcus neoformans. J. Bacteriol. 87:1364-1368. 1964.-A group of 39 white Swiss male mice were allowed to run 3 days on previously sterilized soil that had been seeded with Cryptococcus neoformans 1 year previously. It was determined that the soil contained an average of 1.6 x 10(6) viable yeast cells per ml. The mice were observed for 24 weeks, at which time the survivors were necropsied. The total mortality rate during this period was 44%; 67% of the mice had positive cultures, including all who had a fatal infection. Two additional experiments were done with the same strain with the use of aerosols produced by a Henderson apparatus. In experiment 1, 39 mice received 11,000 viable cells each; in experiment 2, 40 mice received 14,622 viable cells. Both groups of mice showed similar mortality rates, with a total of 77% dead after 20 weeks in experiment 1, and 80% in experiment 2. All of the mice in experiment 1 had positive cultures, as did 95% of the mice in experiment 2.

Aerosols↗

PubMed1975

Pigment production by Cryptococcus neoformans from para- and ortho-Diphenols: effect of the nitrogen source.

Cryptococcus neoformans produced pigments when p-diphenols were substrates in a glucose-amino acid-salts medium. The best substrates were 2.5-dihydroxybenzoic acid and 2,5-dihydroxybenzenesulfonic acid. In contrast to the cellular pigment production from o-diphenols (hydroxyl groups in the 2,3- or 3,4-position of phenyl ring), the p-diphenols (1,4- or 2,5-positions for the hydroxyl groups) produced large amounts of soluble pigments that diffused into the medium. When an optimal source of nitrogen (glutamine, glycine, and asparagine) was used, 89% of the C. neoformans strains produced pigments from p-diphenols. In contrast, 0 to 67% of the strains produced pigments when a suboptimal nitrogen source (proline, ammonium sulfate, ornithine, and methionine) was used. When glutamine-glycine-asparagine was the nitrogen source, 100% of the C. neoformans strains produced pigments from o0diphenols, whereas 77 to 100% of the strains produced pigment when proline-ammonium sulfate-ornithine-methionine was the nitrogen source. Cryptococcus species other than C. neoformans and all tested Candida species failed to produce pigments from any of the substrates except when hydroquinone was used. A combination of glutamine-glycine-asparagine and 3,4-dihydroxyphenylalanine allowed differentiation of colonies of C. neoformans from C. albicans in 3 to 6 days. These data showed that pigment production from o- and p-diphenols served as an excellent biochemical test for the identification of C. neoformans.

Asparagine↗

PubMed1982

Antigenic characterization of Cryptococcus neoformans serotypes and its application to serotyping of clinical isolates.

Antigenic analysis of the four serotypes of Cryptococcus neoformans was carried out by slide agglutination with reciprocal adsorption methods. With this procedure the antigenic patterns of the serotypes were established. Serotypes A and D had antigenic factors 1, 2, 3, 7 and 1, 2, 3, 8, respectively. Serotypes B and C were found to have antigenic factors 1, 2, 4, 5 and 1, 4, 6, respectively. Factor sera, prepared according to the antigenic patterns demonstrated by adsorption studies, proved to be useful for rapidly and accurately identifying C. neoformans serotypes. Some patterns similar to those of the C. neoformans serotypes were observed in five other Cryptococcus species and two Candida species. The proton magnetic resonance spectra of polysaccharides from the C. neoformans serotypes correlated well with their antigenic characteristics. Phenol oxidase test reactions and growth at 37 degrees C were useful criteria for determining which yeasts should be chosen for clinical application of factor sera for serotyping of C. neoformans. Sixty-two Japanese isolates of C. neoformans were serotyped. Fifty-eight of these isolates were serotype A, three were serotype A-D, and one was serotype D.

Agglutination Tests↗

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↗

PubMed1978

Rapid presumptive identification of Cryptococcus neoformans.

Carbohydrate-containing extracts were prepared from mature yeast colonies grown on Sabouraud dextrose agar by mixing a 0.001-ml loopful of yeast cells for 30 s in phenolized saline and removing the cells by centrifugation. Extracts were prepared from 54 Cryptococcus neoformans isolates, 29 isolates of other Cryptococcus species, 16 isolates of Candida species, 2 Rhodotorula, 2 Torulopsis, and 1 Saccharomyces species. Initially the carbohydrate content of each extract was estimated (Molisch method) and adjusted to 1, 5, and 10 microgram/ml. Twofold dilutions of each extract were tested for reactivity with the cryptococcal latex agglutination reagent of Bloomfield et al. (N. Bloomfield, M.A. Gordon, and D.F. Elmendorf, Jr., Proc. Soc. Exp. Biol. Med. 114:64-67, 1963). All 54 C. neoformans extracts gave strong agglutinations (3+ to 4+) in dilutions of 1:4 or greater. None of the other yeasts produced any agglutination, except for 1 of 15 C. laurentii isolates, which showed a 1+ reaction that disappeared at a dilution of 1:4 and above. Subsequent testing established that a single extract made from 0.001 ml of yeast cells in 6 ml of phenolized saline contained less than 5 microgram of carbohydrate per ml, was suitable for a single rapid screening dilution, and eliminated any cross-reaction from the C. laurentii isolates. In our hands this method has provided a reliable differentiation of C. neoformans from other unknown yeast colonies in less than 20 min exclusive of a Molisch determination.

Candida↗

PubMed1990

Utilization by yeasts of D-glucarate, galactarate, and L-tartarate is uncommon and occurs in strains of Cryptococcus and Trichosporon.

In 38 yeast genera tested, utilization of D-glucarate was uncommon, occurring with only 10 strains out of 373. The ability was prominent among Cryptococcus strains, with 8 out of 8 tested being positive, including the pathogen Cryptococcus neoformans. The ability was present also in Trichosporon where 2 out of the 4 strains tested were positive. There was a correlation between ability to utilize D-glucarate, galactarate, L-tartarate, and D-glucuronate. Use of L-ascorbate occurred in more genera than use of D-glucarate, but all strains that grew on D-glucarate grew on L-ascorbate. The utilization of certain hydroxylated carboxylates by strains, mainly found in two genera, is of interest in identifying the catabolic pathways involved, in taxonomic studies, and in developing rapid methods of yeast identification.

Ascorbic Acid↗

PubMedDate not supplied

Frequency of Cryptococcus species and varieties in México and their comparison with some Latin American countries.

Cryptococcosis frequency is increasing in Mexico. Few epidemiologic and clinical surveys exist even though 10-15% of patients with AIDS develop this mycosis. To know the situation about the prevalence and etiological agents of cryptococcosis in our country, a study including isolated Cryptococcus spp. strains took place from 1989 to August 1998. A total of 211 Cryptococcus spp. strains obtained from patients of diverse hospital centers in Mexico City were studied. This study describes cryptococcosis epidemiological data, in our country. C. neoformans was the dominant isolation (97.15%), followed by two C. albidus isolation and one C. uniguttulatus isolation. 92.5% of the strains was isolated from cerebral spinal fluid and the remaining were from bone marrow, blood, ganglion, sputum, bronchial lavage and liver biopsy. AIDS was the principal opportunistic factor (85%). Strains were found prevails in males (87.3%). It was found that the age groups where the disease appears most frequently are in the fourth (37.5%) and third (33.8%) decade of life. Finally, the isolation frequency of the C. neoformans var. neoformans (vn) and var. gattii (vg) obtained in this study (vn 86.7%) and vg 10.4%) was compared with the ones registered in Argentina (vn 97.6%, vg 2.4%); Brazil (vn 83.3%, vg 15.8%); Cuba (vn 97.6%, vg 2.4%); Paraguay (vn 0%, vg 100.0%); Puerto Rico (vn 100.0%, vg 0%) and Venezuela (vn 66.7%, vg 29.6%).

AIDS-Related Opportunistic Infections↗

PubMedDate not supplied

Cytologic detection of Cryptococcus neoformans in cerebrospinal fluid. Rapid screening methods.

Yeasts of Cryptococcus neoformans in cerebrospinal fluid (CSF) were studied using polarized light and fluorescence microscopy. Ultraviolet-induced fluorescence of wet-fixed, Papanicolaou-stained smears and polarization of air-dried, Diff-Quik or Leishman-stained preparations are complementary methods that allow for rapid screening for and immediate identification of Cryptococcus in cytologic preparations of CSF.

Birefringence↗

PubMed1983

Isolation of Cryptococcus neoformans, Candida albicans and other yeasts from pigeon droppings in Egypt.

Two hundred pigeon droppings, unmixed with soil, and collected from various provinces in lower Egypt (Delta) were cultured to detect yeasts. Yeasts were isolated from 53.5% of the samples; Cryptococcus neoformans was recovered from 30 samples and Candida albicans from 19 samples. Other Cryptococcus and Candida species as well as species of Torulopsis and Rhodotorula were also encountered. Aspergillus fumigatus was isolated on 13 occasions.

Animals↗

PubMed1976

Six-hour pigmentation test for the identification of Cryptococcus neoformans.

Cryptococcus neoformans colonies can be identified within 6 h using paper disks containing caffeic acid and ferric citrate. Indentification is based on the development of a dark brown pigment. Saprophytic Cryptococcus species and common clinically isolated yeasts do not develop the brown color. The concentration of the reagents and the method of storage of the impregnated paper disks are critical for the rapid and specific development of the pigment.

Caffeic Acids↗