Histoplasma capsulatum
| Histoplasma capsulatum | ||||||||||||
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Histoplasma capsulatum var. Duboisii , some cells are multiplying by sprouting |
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| Scientific name | ||||||||||||
| Histoplasma capsulatum | ||||||||||||
| Darling |
Histoplasma capsulatum is a dimorphic fungus thatcan occurin a yeast and a mycelium or mold form . It is of medical importance as the causative agent of histoplasmosis , a systemic fungal disease ( mycosis ) in humans.
description
The morphology of Histoplasma capsulatum is temperature-dependent; at 25 ° C it takes on the mold form, at 37 ° C it takes on the yeast form. As a yeast, which is also the infectious form, the single cells in the capsulatum variety are rather small (2–3 µm), but significantly larger in the duboisii variety (6–12 µm), which only occurs in Africa. In the Giemsa and Gram staining , the cell wall does not take on any color, so that the yeasts appear to be surrounded by an empty shell structure, which was previously misinterpreted as a capsule (hence capsulatum ). For histological staining come methenamine - silver staining after Gömöri or cotton blue Lactophenol solution (from methylene blue and Lactophenol) in question, which may also represent the septierenden hyphae.
The yeast form multiplies by sprouting . At lower temperatures, the mycelium form, which forms spores ( conidia ). It can also be grown as a culture on nutrient media, with an incubation period of several weeks being necessary.
distribution
Histoplasma capsulatum is common in the warm regions of the world (tropical and subtropical America, Africa and Indonesia). Its natural habitat is the ground.
swell
- Kayer, Bienz, Eckert, Zinkernagel: Medical Microbiology. 9th edition. Thieme, Stuttgart 1998, ISBN 3-13-444806-8 .
- Katrina A. Armstrong, Justine V. Cohen, Jo-Anne O. Shepard, Erik E. Folch, Michael K. Mansour, Jonathan A. Stefely: Case 16-2020: A 47-Year-Old Woman with Recurrent Melanoma and Pulmonary Nodules . New England Journal of Medicine 2020, Issue 21 May 21, 2020, pages 2034-2043, DOI: 10.1056 / NEJMcpc1916258 - Case Description of Pulmonary Histoplasmosis
