Intra-strain variability of Cryptococcus neoformans can be detected on Phloxin B medium

Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, (260-8673), Japan.
Journal of Basic Microbiology (Impact Factor: 1.82). 05/2002; 42(2):111-9. DOI: 10.1002/1521-4028(200205)42:2<111::AID-JOBM111>3.0.CO;2-3
Source: PubMed


A method was devised for easy detection of intra-strain variability of the human pathogenic yeast Cryptococcus neoformans. Cultivation of strains on a medium containing Phloxin B resulted in different coloured colonies. Generally, colonies were either pink or red; however there were also several colony-colour segregant in which both colours could be observed. A number of these segregants were isolated and analysed. Virulence factors such as the cell and capsule sizes were measured; further temperature sensitivity, growth rates, mating-types and melanin production were also studied. Segregants were examined by random amplified polymorphic DNA (RAPD) fingerprinting and electrophoretic karyotyping by pulsed-field gel electrophoresis (CHEF). They showed both phenotypic and genotypic differences. The main differences appeared in phenotypic characters and RAPD patterns; while the chromosomal patterns remained unchanged. Reversion frequency analysis revealed that the reason for this segregation could be due to phenotypic switching. The physiological reason for the colour changes was also investigated and was attributed to the differential ability of the cells to accumulate Phloxin B either into their capsules or into their cells. The method described here is potentially applicable for the detection of strain heterogeneity in both basic and clinical microbiology laboratories.

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    • "The lack of tissue reaction to the typical encapsulated form of C. neoformans is associated with the existence of the capsule material. The capsule is a very important virulence factor in the pathogenicity of C. neoformans, which can alter leukocyte migration, phagocytosis and killing by the immune effector cells10, 11). The loss of capsule material elicits an intense inflammatory response that includes early suppuration, phagocytosis and granuloma formation4, 12). "
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    ABSTRACT: Pulmonary infection by capsule-deficient Cryptococcus neoformans (CDCN) is a very rare form of pneumonia and it is seldom seen in the immunocompetent host. The authors experienced a case of pulmonary cryptococcosis by CDCN in 25-year-old woman who was without any significant underlying disease. The diagnosis was made from the percutaneous lung biopsy and special tissue staining, including Fontana-Masson silver (FMS) staining. Fungal culture confirmed the diagnosis afterward. Her clinical and radiologic features improved under treatment with fluconazol. It's known that CDCN is not so readily confirmed because fungal culture does not always result in growth of the organism and the empirical fungal stain is not helpful for the differentiation between CDCN and the other infections that are caused by the nonencapsulated yeast-like organisms. In this report, we emphasize the diagnostic value of performing FMS staining for differentiating a CDCN infection from the other confusing nonencapsulated yeast-like organisms.
    The Korean Journal of Internal Medicine 04/2006; 21(1):83-7. DOI:10.3904/kjim.2006.21.1.83 · 1.43 Impact Factor
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    • "Cell viability was determined by either staining with phloxin B [16] or spotting known numbers of cells on YPAD agar plates after sequential dilution. "
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    ABSTRACT: We compared the clinical manifestations, laboratory and radiologic findings, and outcomes of eight patients with proven pulmonary cryptococcosis (PC) caused by capsule-deficient Cryptococcus neoformans with those of six patients with PC caused by capsule-intact Cr. neoformans. The presentations and outcomes did not differ significantly between the groups.
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