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PubMed1964

CHARACTERIZATION OF THE PYROGENICITY OF CANDIDA ALBICANS, SACCHAROMYCES CEREVISIAE, AND CRYPTOCOCCUS NEOFORMANS.

Kobayashi, George S. (Tulane University, New Orleans, La.), and Lorraine Friedman. Characterization of the pyrogenicity of Candida albicans, Saccharomyces cerevisiae, and Cryptococcus neoformans. J. Bacteriol. 88:660-666. 1964.-The intravenous injection into rabbits of 10(9) yeast cells of Candida albicans, Saccharomyces cerevisiae, or Cryptococcus neoformans (both slightly and heavily encapsulated forms) induced a febrile response indistinguishable from that elicited by gram-negative bacterial endotoxin. There was a brisk rise in body temperature which began as early as 30 min after injection, peaked once or twice, and then returned to normal after about 10 hr. With viable C. albicans, the febrile response did not return to normal but remained elevated for several days and terminated at death of the animal. Of three extraction procedures employed in attempts to isolate the endotoxin-like pyrogenically active substances from C. albicans, only one, the phenol extraction method, was successful. Pyrogenic substances were more easily extractable from S. cerevisiae, but extracted cells of both species were still highly pyrogenic. It was concluded that the particulate nature of the yeast cell did not contribute to the induction of fever, for latex particles of a similar size were nonpyrogenic. Viable or heat-killed C. albicans, phenol extract of C. albicans, zymosan, and polystyrene latex particles all failed to induce in rabbits increased dermal reactivity to epinephrine.

Animals↗

PubMed1990

Periorbital necrotising fasciitis due to Cryptococcus neoformans in a healthy young man.

A case report is presented of a healthy 25-year-old man who developed a periorbital necrotising fasciitis after a trivial trauma with a wooden splinter. Necrotising fasciitis of the eyelids occurs rarely. Cryptococcus neoformans is not described as a causative factor of necrotizing fasciitis. Cryptococcus neoformans usually infects patients with immunodeficiencies, diabetes mellitus or steroid therapy. This patient was healthy and developed a periorbital necrotising fasciitis due to Cryptococcus neoformans.

Adult↗

PubMed2025

Unisexual reproduction in the global human fungal pathogen Cryptococcus neoformans.

The human fungal pathogen Cryptococcus species complex (encompassing C. neoformans, C. deneoformans, and the C. gattii species complexes) exhibit diversity in sexual reproduction, including α-a mating, pseudosexual reproduction, as well as unisexual reproduction initiated from a single isolate or between isolates of the same mating type. A central conundrum is that while most Cryptococcus natural populations exhibit significant α mating-type bias, genetic and genomic analyses show recombination occurs in nature. The discovery of unisexual reproduction in C. deneoformans provided insight; however, thus far unisexual reproduction has never been directly observed in the predominant global pathogenic species C. neoformans. Here, we provide evidence that mutating the RIC8 gene, which encodes a conserved guanine nucleotide exchange factor (GEF) involved in both chaperoning and activating Gα proteins, enables unisexual reproduction in C. neoformans. Additionally, we show that genetic variation in the natural population promotes unisexual reproduction, and unisexual reproduction in C. neoformans involves canonical meiotic recombination. Finally, we found that deletion of both GPA2 and GPA3 in the MATα background leads to self-filamentation without sporulation, suggesting that differential modulation of the Gα proteins, likely involving Ric8, could underlie the switch between different modes of sexual reproduction in Cryptococcus. Our study further highlights that the highly conserved Ric8 GEF can act as an important regulator of cellular development in response to environmental stimuli and could modulate sexual reproduction in nature. We hypothesize that unisexual reproduction occurs much more frequently in nature than currently appreciated, and possibly in other fungi and microbial eukaryotes as well.

G protein↗

PubMed2000

Cutaneous cryptococcus infection due to C. albidus associated with Sézary syndrome.

Cryptococcus albidus is a non-neoformans species of the genus Cryptococcus and is a rare cause of disease. There have been only 13 previously reported cases of systemic disease in which this opportunistic yeast has been isolated from the lung, cerebrospinal fluid and blood. We report the first case of cutaneous Cryptococcus infection due to the species C. albidus, in a man with Sézary syndrome.

Aged↗

PubMed1997

Primary cryptococcal cellulitis caused by Cryptococcus neoformans var. gattii in an immunocompetent host.

Primary cutaneous cryptococcal infection is uncommon. The cutaneous manifestations are most often the result of dissemination from the central nervous system or lung, usually in an immunocompromised host; cellulitis is regarded as the rarest cutaneous form. Primary cutaneous cryptococcosis has occasionally been reported in the immunocompetent, the causative organism being Cryptococcus neoformans var. neoformans. We present a case of cellulitis of the right arm in a 75-year-old man caused by Cryptococcus neoformans var. gattii, a fungus which is endemic in Australia and an important cause of infection in the immunocompetent. This is the first case described of a primary cutaneous infection due to Cryptococcus neoformans var. gattii. The interesting ecology of this organism is discussed.

Aged↗

PubMedDate not supplied

Cytologic diagnosis of Cryptococcus neoformans in HIV-positive patients.

OBJECTIVE: To present experience with the cytologic diagnosis of pulmonary cryptococcosis in bronchial washings and bronchoalveolar lavage in human immunodeficiency virus (HIV)-positive patients in Thailand. STUDY DESIGN: The study group consisted of 54 HIV-positive patients admitted to the Faculty of Medicine, Srinagarind Hospital, during the period January 1992-June 1994. Bronchial washing and bronchoalveolar lavage specimens were studied for Cryptococcus neoformans by routine Papanicolaou and special staining methods. RESULTS: The Cryptococcus organism, an encapsulated yeast with a clear halo on Papanicolaou-stained smears, was found both extracellularly and in histiocytes in 4 of 54 (7.4%) cases. A definitive diagnosis was confirmed by positive staining of the capsular mucopolysaccharides with periodic acid-Schiff and Mayer's mucicarmine stain and of the cell wall with methenamine silver. Lung biopsy was performed in one case and revealed cryptococcosis. CONCLUSION: This study underscores the usefulness of cytologic screening in the detection of this opportunistic pulmonary infection. The cytopathologist and cytotechnologist should be alert for the presence of Cryptococcus in cytologic specimens from HIV-positive patients.

AIDS-Related Opportunistic Infections↗

PubMed2004

First report of Cryptococcus albidus--induced disseminated cryptococcosis in a renal transplant recipient.

Cryptococcus albidus, a non-neoformans species of the genus Cryptococcus, is generally regarded as a rare cause of disease. There have been only 14 previously reported cases in which this organism has been isolated as a pathogen, none of which occurred in a renal transplant recipient. A 23-year-old renal transplant recipient taking medication consisting of cyclosporine and prednisolone was admitted with a 10-day history of dry cough, fever and progressive dyspnea. The next day, his respiratory status deteriorated dramatically, and he developed acute respiratory distress syndrome (ARDS) and fulminant septic shock. On the eighth hospital day, tender macules on both his shins coalesced to form erythematous patches. Cryptococcus albidus was isolated by skin biopsy and tissue culture. We report here the first case of disseminated cryptococcosis caused by C. albidus in a renal transplant recipient who had been successfully treated with fluconazole monotherapy.

Adult↗

PubMed1996

Cutaneous Cryptococcus infection and AIDS. Report of 12 cases and review of the literature.

BACKGROUND: Cryptococcal infections occur in 6% to 13% of patients with acquired immunodeficiency syndrome (AIDS), most commonly infecting the central nervous system. Cutaneous lesions have been described morphologically as umbilicated papules, nodules, and violaceous plaques and can mimic molluscum contagiosum and Kaposi's sarcoma. Cutaneous lesions can present months prior to other signs of systemic infection. OBSERVATIONS: Cases of infection with cutaneous Cryptococcus and AIDS were reviewed and compared with cases reported in the literature. Among patients with Cryptococcus infection and AIDS seen at our institutions, 5.9% had skin lesions. All patients with cutaneous lesions had systemic involvement. Women were less commonly infected than men. There was no apparent predisposition associated with age, race, or human immunodeficiency virus infection risk factors. The median CD4 helper T-cell count was 0.024 X 10(9)/L (24/microL), and 44% (16/36) of the patients had previous opportunistic infections. Lesions were most commonly seen on the head and neck (78% [36/46]) and often mimicked molluscum contagiosum (54% [25/46]). The median serum and cerebrospinal fluid cryptococcal antigen titers were 1:32,768 and 1:512, respectively. Patients in our group did well with therapy (one death at 6 weeks, compared with 38% [13/34] mortality in the literature). There was no correlation between onset of lesions, number of lesions, CD4 helper T-cell count, or histopathologic characteristics. CONCLUSIONS: Disseminated Cryptococcus infection in AIDS presents with cutaneous lesions in up to 6% of cases. Clinicians need to be aware of the varied morphologic characteristics, since cutaneous lesions may present well in advance of other signs of systemic infection.

AIDS-Related Opportunistic Infections↗

PubMed1978

An ultrastructural examination of the interaction between macrophages and Cryptococcus neoformans.

The interaction of mononuclear phagocytes with Cryptococcus neoformans was examined in vitro and in vivo using ultrastructural techniques. Immune serum roughens the surface of the yeast and in the first 2 hr, increases the number of organisms attaching to the macrophage surface, as well as the number of contacts between individual yeasts and the phagocyte. Contact is established by means of thin filopodia and cytoplasmic flaps. During the next few days the macrophages increase in size, and, by intimate apposition of their contiguous cell surfaces, a cellular barrier surrounds the now enclosed yeast. These events are accompanied by thinning of fungal capsule, degradation of the enclosed cryptococcus, and the formation of macrophage polykaryons. Electron cytochemical techniques for peroxidase reveal that these multinucleated cells are formed predominantly by the fusion of stimulated macrophages. Destruction of the enclosed yeast probably results from the secretion of various agents by the surrounding cells.

Animals↗

PubMed1986

Cryptococcus neoformans: comparisons of in vitro antifungal susceptibilities of serotypes AD and BC.

Thirty-nine isolates of Cryptococcus neoformans, nineteen serotype AD and twenty serotype BC, were assayed for susceptibility to eight antifungal agents using an in vitro agar dilution assay. Media employed were Kimmig agar and yeast nitrogen base supplemented with 10% glucose. The antifungal agents used were ketoconazole, amphotericin B, 5-fluorocytosine, nystatin, miconazole, BAY N 7133, ICI 153,066, and itraconazole. No clinically significant differences in vitro minimum inhibitory concentrations were detected between serotypes AD and BC against any of the compounds tested. An adverse medium effect was observed in two of the assays, but the outcome of the AD/BC comparison was not affected. This is the first report in which the in vitro antifungal susceptibilities of Cryptococcus neoformans serotypes are analyzed.

Amphotericin B↗

PubMed1978

Epidemiology of Cryptococcus neoformans.

The concept of the epidemiology of Cryptococcus neoformans as the causative agent of cryptococcosis and as a basidiomycetous yeast is based on the fact that bird manure has been until now its only known habitat but not plant material which likewise harbours various nonpathogenic Cryptococcus species. It could be shown that the possible influence of nutritional factors on the morphology and morphogenesis earns attention not only in view of the epidemiology of C. neoformans but of its perfect states, too.

Animals↗

PubMed1986

In vivo and in vitro studies with an atypical, rhinotropic isolate of Cryptococcus neoformans.

An atypical isolate of Cryptococcus neoformans was investigated because of its consistent and reproducible production of gross nasal pathology following i.v. injection in Swiss albino mice. Dose response to graded concentrations ranging from 1 X 10(2)-1 X 10(7) cells/mouse yielded an LD50 of 1.4 X 10(3) cells/mouse for the atypical rhinotropic strain H140 which was significantly less virulent (p less than 0.01) than our reference strain of Cryptococcus neoformans. There was no significant difference in mortality following the injection of in vitro vs. in vivo passed inoculum. As early as two weeks after inoculation, this strain produced gross nasal enlargement to approximately 2-3 X normal dimensions with granulomatous and ulcerated lesions. The LD60 resulted in the greatest percentage of nasal involvement (85%). C. neoformans was demonstrated by culture and histopathology in the noses, brains, lungs, livers and kidneys. A temperature selection was indicated by findings of a lower temperature minimum for subcultures isolated from the noses relative to those isolated from the brain, and by the fact that the most densely populated organs following intraperitoneal injection were the testes. This route of inoculation resulted in cutaneous nasal involvement in a manner analogous to that following i.v. injection. The atypical isolate was unable to assimilate trehalose or raffinose but otherwise was entirely consistent with identification as C. neoformans and produced characteristic CNS and general organ system disease in addition to the rhinotropic cutaneous manifestations. The model characterized here in normal mice may be of value in studies of fungal dermotropism.

Animals↗

PubMed1984

Growth inhibition of Cryptococcus neoformans by cloned cultured murine macrophages.

Cloned and unselected bone marrow-derived macrophage cell lines were obtained from A/J, AKR/J, BIO.A(5R), CBA/J, DBA/2, HPC, NZW, and [NZB X NZW]F1 mice, and their interactions were studied in vitro with a lightly encapsulated natural serotype A isolate of Cryptococcus neoformans. Growth inhibition of C. neoformans was seen with all of the cell lines, as determined by enumeration of colony-forming units. Inhibition was enhanced by a high concentration (8%) of fresh mouse serum and was the same for serum obtained from AKR/J (C5 deficient) and BIO.A (C5 normal) mice. Macrophage incubation with fresh AKR/J serum which had been absorbed with heat-killed Cryptococcus cells also inhibited C. neoformans growth. Heat-inactivation, EDTA addition or anti-C3 antibody treatment of fresh serum abolished the opsonic activity for C. neoformans, while EGTA addition to fresh serum was without effect on opsonization. In addition, neither IgM nor IgG1 murine monoclonal antibodies specific for C. neoformans enhanced phagocytosis or killing of the yeast by macrophages. These findings are consistent with the interpretation that C3b is an important modulator of interactions between macrophages and C. neoformans.

Animals↗

PubMed1990

An anti-Cryptococcus neoformans monoclonal antibody directed against galactoxylomannan.

Six monoclonal antibodies (mAb) were produced by immunizing mice with a Cryptococcus neoformans serotype A spheroplast lysate (CNSL). Two mAb were of the IgG1 isotype; the others were IgM. The results obtained with one IgM mAb (CN6) are reported herein. This mAb recognized the four serotypes of C. neoformans and no cross-reactions were observed with extracts from Cryptococcus melibiosum, Candida albicans, Saccharomyces cerevisiae, Torulopsis glabrata or Trichosporon beigelii. Fractionation of the CNSL by gel filtration revealed that mAb CN6 recognized high molecular weight substances as well as a range of smaller molecules. Indirect ELISA inhibition studies showed that this mAb recognized substances in a cryptococcal culture filtrate. Inhibition studies and agglutination tests using latex beads sensitized with purified CN6 showed that CN6 strongly reacted with the C. neoformans serotype A cell envelope galactoxylomannan-mannoprotein complex (GAlXM-MP) and only weakly with the glucuronoxylomannan (GXM) component. These tests also showed that purified galactoxylomannan (GalXM) from C. neoformans serotype A was more reactive than purified mannoprotein (MP). An anti-GalXM mAb might be a useful tool for monitoring the clinical course of cryptococcal infections.

Animals↗

PubMed2005

Comparative analysis of the intergenic spacer regions and population structure of the species complex of the pathogenic yeast Cryptococcus neoformans.

Cryptococcus neoformans is an opportunistic basidiomycete responsible for the high incidence of cryptococcosis in patients with AIDS and in other immune-compromised individuals. This study, which focused on the molecular structure and genetic variability of the two varieties in the C. neoformans and Cryptococcus gattii species complex, employed sequence analysis of the intergenic spacer regions, IGSI and IGSII. The IGS region is the most rapidly evolving region of the rDNA families. The IGSI displayed the most genetic variability represented by nucleotide base substitutions and the presence of long insertions/deletions (indels). In contrast, the IGSII region exhibited less heterogeneity and the indels were not as extensive as those displayed in the IGSI region. Both intergenic spacers contained short, interspersed repeat motifs, which can be related to length polymorphisms observed between sequences. Phylogenetic analysis undertaken in the IGSI, IGSII and IGSI +5S rRNA + IGSII regions revealed the presence of six major phylogenetic lineages, some of which segregated into subgroups. The major lineages are represented by genotypes 1 (C. neoformans var. grubii), genotype 2 (C. neoformans var. neoformans), and genotypes 3, 4, 5 and 6 represented by C. gattii. Genotype 6 is a newly described IGS genotypic group within the C. neoformans species complex. With the inclusion of IGS subgenotypic groups, our sequence analysis distinguished 12 different lineages. Sequencing of clones, which was performed to determine the presence of multiple alleles at the IGS locus in several hybrid strains, yielded a single IGS sequence type per isolate, thus suggesting that the selected group of cloned strains was mono-allelic at this locus. IGS sequence analyses proved to be a powerful technique for the delineation of the varieties of C. neoformans and C. gattii at genotypic and subgenotypic levels.

Alleles↗

PubMed1999

The green colour effect (GCE) of the killer strain Cryptococcus laurentii CBS 139 on Staib agar.

Attention is drawn to the observation that the type strain Cryptococcus laurentii CBS 139, producing killer toxins (mycocins) directed at Cr. neoformans var. gattii, causes a green colour effect (GCE) on Staib agar (Guizotia abyssinica creatinine agar) in combination with an intense assimilation of creatinine. Five (9.6%) out of 52 strains of Cr. laurentii of various origin, showed a GCE and intense creatinine assimilation. Further research must show if all Cr. laurentii strains, characterized by a GCE similar to that of the strain CBS 139, are also capable of producing killer toxins. For further ecological and epidemiological research on strains producing killer toxins directed against species of the genus Cryptococcus, it is proposed to use Staib agar as differential culture medium indicating both colour effects, i.e. the GCE and the brown colour effect (BCE).

Color↗

PubMed1979

Survey of Cryptococcus neoformans in the respiratory tract of patients with bronchopulmonary disorders and in the air.

Cryptococcus neoformans was cultured from 9 (1%) of 835 clinical specimens examined from the respiratory tract of patients. These isolations came from 3 (0.4%) of the760 patients; 8 isolates were from sputum and one from urine. The fungus was not demonstrable in the air at a selected site during a 2-year study although other species of Cryptococcus, namely, C. albidus, C. ater, C. flavus, C. laurentii, C. magnus, C. terreus and C. uniguttulatus were isolated. The three C. neoformans positive patients were males, with pulmonary tuberculosis as the primary disease and history of repeated exposure to pigeon excreta in two. None of these patients manifested any overt signs and symptoms specificially attributable to cryptococcosis, nor did they receive any antifungal therapy. Repeated isolations of C. neoformans from sputum, a positive urine culture and demonstration of cryptococcal antibodies in a serum specimen, followed by negative cultures and serology, suggested that patient 1 had spontaneously recovered from an episode of benign, minimal pulmonary cryptococcosis. Patients 2 and 3 probably carried the fungus as a transient resident of the respiratory tract. The results suggest that C. neoformans is of uncommon occurrence in the respiratory tract of patients with bronchopulmonary disorders and that the isolation of the fungus from this site may not necessarily imply an etiologic relationship.

Adult↗

PubMedDate not supplied

The 5S rRNA and the rRNA intergenic spacer of the two varieties of Cryptococcus neoformans.

The intergenic spacers (IGS) separating the 23S-like and 16S-like rDNAs of the two varieties of the human pathogenic fungus Cryptococcus neoformans were amplified, cloned and sequenced. The C. neoformans var. neoformans IGS was 2421 nt with 5S rRNA at positions 1228-1345 3' of the 23S-like rRNA. The C. neoformans var. gattii IGS was 2480 nt with 5S rRNA at positions 1268-1385 3' of the 23S-like rRNA. For both varieties the 5S rDNA genes were in the same orientation as the 16S-5.8-23S genes and encode a 118 nt molecule of identical sequence. Phylogenetic comparison of C. neoformans 5S rDNA with that of other fungi placed this fungus in close relationship with other basidiomycetes including Tremella mesenterica, Bullera alba, and Cryptococcus laurentii. A secondary structure model for the deduced 5S rRNA was constructed by comparative sequence analysis. Polymerase chain reaction-amplified IGS of 12 C. neoformans var. neoformans strains revealed extensive size variation ranging from 100 to 300 nt. Size variation between strains in the length of the IGS may be useful for distinguishing strains. Structurally, the IGS were characterized by the presence of occasional short direct GC-rich 19-nt repeats. Overall IGS sequence identity between the C. neoformans varieties was only 78.5%, in sharp contrast to the identical or nearly identical sequences for the rDNA genes, and suggests rapid evolution for IGS sequences.

Base Sequence↗