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Blastoschizomyces sp.
(described by Salkin, Gordon, Sams, and Rieder in 1982)
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Kingdom: Fungi
Phylum: Ascomycota
Class: Ascomycetes
Order: Saccharomycetales
Family: Saccharomycetaceae
Genus: Blastoschizomyces
Blastoschizomyces is a yeast isolated from soil, beach sand, poultry feces, and wood pulp. As well as being an environmental saprobe, it is found in normal microbial flora of human skin, and digestive and respiratory tracts.
The genus Blastoschizomyces currently contains a single species, Blastoschizomyces capitatus.
Blastoschizomyces pseudotrichosporon
Trichosporon capitatum
Geotrichum capitatum
Formerly known as Trichosporon capitatum and classified in Basidiomycetes, this fungus was later found to be more closely related to Ascomycetes based on its cell wall structure, septal pores, G+C content, and production of numerous arthroconidia and few blastoconidia. Its teleomorph Dipodascus capitatus producing ascospores was then discovered, strengthening its classification in class Ascomycetes. Prior to its transfer to the new genus, Blastoschizomyces, this fungus was included in genus Geotrichum. However, its property to produce annelloconidia as well as arthroconidia led to general acceptance of its classification in a new genus, Blastoschizomyces.
Blastoschizomyces capitatus is an emerging opportunistic fungus potentially pathogenic in cases of immunosuppression [1455]. Neutropenic patients, as well as those receiving chemotherapy, corticosteroids or antibiotics are at risk. Surgery, drug abuse, catheters, and low dose azole treatment have also been reported as predisposing factors [462]. Clinical manifestations of Blastoschizomyces capitatus infections are diverse. Immunocompetent hosts may also develop Blastoschizomyces capitatus infections. Onychomycosis has been reported in an otherwise healthy individual [504]. Infusion of intravenous fluids contaminated with Blastoschizomyces capitatus has been ultimately fatal in a six-month old infant who had no proven immunosuppression [1466].
Fungemia and disseminated infections are likely in immunocompromised hosts [1249, 1251]. The lungs, kidneys, liver, spleen, brain and endocardium may be involved [564, 1247]. Endocarditis, osteomyelitis, meningitis, encephalitis, urinary tract infection, mycetoma and pneumothorax may develop [846, 1247].
Colonies of Blastoschizomyces capitatus grow rapidly and mature in about 5 days. The texture of the colony is yeast-like, and white to cream colored. It becomes mould-like, wrinkled, and develops short aerial hyphae by aging. Blastoschizomyces capitatus can grow at 45°C [462, 1295].
On cornmeal tween 80 agar, Blastoschizomyces capitatus produces budding yeast cells, arthroconidia, annelloconidia, true hyphae and pseudohyphae. Oblong annelloconidia, typical for Blastoschizomyces capitatus, are clustered at the tips of the annellides. Annellides are located along or at the tips of the hyphae [462, 1295].
Pleomorphic yeast-like cells (diameter: 3-8 µm) and septate hyphae are visualized in the infected tissue. Arthroconidia may rarely be observed [462].
Differentiation of annelloconidia is difficult. They may be misidentified as arthroconidia or blastoconidia. Blastoschizomyces capitatus may mostly be misdiagnosed morphologically as Trichosporon spp., Geotrichum candidum, or Candida krusei. While the lack of urease enzyme activity differentiates it from Trichosporon, its growth at 45°C, resistance to cycloheximide and biochemical characteristics help in definitive identification [462, 1295].
No special precautions other than general laboratory precautions are required.
In vitro susceptibility data reported so far are limited. MIC breakpoints for interpretation of in vitro susceptibility results have not been defined. While fluconazole MICs were considerably low [1573], the sordarin compound, GM 237354 [1040], and terbinafine [1990] were also found to be active in vitro against Blastoschizomyces capitatus. Fluconazole and 5-fluorocytosine were more active than amphotericin B and ketoconazole in a comparative in vitro study [2305].
Mortality due to systemic Blastoschizomyces capitatus infections is high. Elimination of the underlying predisposing factors is crucial for clinical cure. None of the available agents are satisfactory for clinical success. Fluconazole therapy may achieve clinical improvement [846].Adjuvant interferon-gamma therapy has been reported to be efficacious in hepatosplenic Blastoschizomyces capitatus infection [564].
For MICs of various antifungal drugs so far reported for Blastoschizomyces capitatus, see our susceptibility database.
PubMed
GenBank
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References
462. Collier, L., A. Balows, and M. Sussman. 1998. Topley & Wilson's Microbiology and Microbial Infections, 9th ed, vol. 4. Arnold, London, Sydney, Auckland, New York.
504. D'Antonio, D., F. Romano, A. Iacone, B. Violante, P. Fazii, E. Pontieri, T. Staniscia, C. Caracciolo, S. Bianchini, R. Sferra, A. Vetuschi, E. Gaudio, and G. Carruba. 1999. Onychomycosis caused by Blastoschizomyces capitatus. J Clin Microbiol. 37:2927-2930.
564. DeMaio, J., and L. Colman. 2000. The use of adjuvant interferon-gamma therapy for hepatosplenic Blastoschizomyces capitatus infection in a patient with leukemia. Clin Infect Dis. 31:822-824.
846. Girmenia, C., A. Micozzi, M. Venditti, G. Meloni, A. P. Iori, S. Bastianello, and P. Martino. 1991. Fluconazole treatment of Blastoschizomyces capitatus meningitis in an allogeneic bone marrow recipient. Eur. J. Clin. Microbiol. Infect. Dis. 10:752-756.
1040. Herreros, E., C. M. Martinez, M. J. Almela, M. S. Marriott, F. G. De Las Heras, and D. Gargallo-Viola. 1998. Sordarins: in vitro activities of new antifungal derivatives against pathogenic yeasts, Pneumocystis carinii, and filamentous fungi. Antimicrob. Agents Chemother. 42:2863-9.
1247. Krcmery, S., M. Dubrava, and V. Krcmery, Jr. 1999. Fungal urinary tract infections in patients at risk. Int J Antimicrobial Agents. 11:289-291.
1249. Krcmery, V., Jr., F. Mateicka, A. Kunova, S. Spanik, J. Gyarfas, Z. Sycova, and J. Trupl. 1999. Hematogenous trichosporonosis in cancer patients: report of 12 cases including 5 during prophylaxis with itraconazol. Support Care Cancer. 7:39-43.
1251. Krcmery, V., I. Krupova, and D. W. Denning. 1999. Invasive yeast infections other than Candida spp. in acute leukaemia. J Hosp Infect. 41:181-194.
1295. Larone, D. H. 1995. Medically Important Fungi - A Guide to Identification, 3rd ed. ASM Press, Washington, D.C.
1455. Martino, P., M. Venditti, A. Micozzi, G. Morace, L. Polonelli, M. P. Mantovani, M. C. Petti, V. L. Burgio, C. Santini, P. Serra, and F. Mandelli. 1990. Blastoschizomyces capitatus: An emerging cause of invasive fungal disease in leukemia patients. Rev. Infect. Dis. 12:570-582.
1466. Mathews, M. S., and S. Sen. 1998. Blastoschizomyces capitatus infection after contamination of fluids for intravenous application. Mycoses. 41:427-428.
1573. Morace, G., S. Manzara, and G. Dettori. 1991. In vitro susceptibility of 119 yeast isolates to fluconazole, 5-fluorocytosine, amphotericin B and ketoconazole. Chemotherapy. 37:23-31.
1990. Ryder, N. S. 1999. Activity of terbinafine against serious fungal pathogens. Mycoses. 42:115-119.
2305. Venditti, M., B. Posteraro, G. Morace, and P. Martino. 1991. In-vitro comparative activity of fluconazole and other antifungal agents against Blastoschizomyces capitatus. J Chemother. 3:13-5.
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