Histoplasma

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Histoplasma
Histoplasma pas-d.jpg
Histoplasma (bright red, small, circular). PAS diastase stain
Scientific classification
Kingdom:
Fungi
Division:
Ascomycota
Class:
Ascomycetes
Order:
Onygenales
Family:
Ajellomycetaceae
Genus:
Histoplasma

Darling (1906)
Type species
Histoplasma capsulatum
Darling (1906)
Species

Histoplasma capsulatum
Histoplasma duboisii

Histoplasma is a genus of dimorphic fungi commonly found in bird and bat fecal material.[1] Histoplasma contains a few species, including—Histoplasma capsulatum—the causative agent of histoplasmosis;[2] and Histoplasma capsulatum var. farciminosum (old term, Histoplasma farciminosum), causing epizootic lymphangitis in horses.[3]

This fungus is mainly found in the Ohio and Mississippi River Valleys in the United States as well as Central/South America, Africa, Asia and Australia.[4]

Forms / Stages[]

Histoplasma capsulatum has two forms: its environmental form is hyphae with microconidia and tuberculate macroconidia while its tissue form is a small intracellular yeast with a narrow neck and no bud with no capsule[5] and can be detected in aerobic blood culture bottle.[6] In the saprophytic stage, it bears features of both microconidia and macroconidia. Infection occurs through inhalation of the small microconidia or small mycelia fragments. The dimorphic mold-yeast transforms and enters host macrophages and proliferates within them most often seen in immunodeficient individuals.[7]

References[]

  1. ^ Giannella RA (1996). Salmonella. In: Baron's Medical Microbiology (Baron S et al, eds.) (4th ed.). Univ of Texas Medical Branch. ISBN 0-9631172-1-1. (via NCBI Bookshelf).
  2. ^ Ryan KJ; Ray CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0-8385-8529-9.
  3. ^ OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals 2004 Chapter 2.5.13, "Archived copy". Archived from the original on 2007-08-04. Retrieved 2007-06-14.CS1 maint: archived copy as title (link)
  4. ^ "Histoplasmosis". Centers for Disease Control and Prevention. 28 October 2020. Retrieved 27 January 2021.
  5. ^ Hutton, JP (April 1985). "Hyphal forms of Histoplasma capsulatum. A common manifestation of intravascular infections". Archives of Pathology and Laboratory Medicine. 109 (4): 330–332. PMID 3885898 – via Pubmed.
  6. ^ Salimnia, Hossein (August 2021). "Hyphal and yeast forms of Histoplasma capsulatum growing within 5 days in an automated bacterial blood culture system". Journal of Clinical Microbiology. 50 (8): 2833–2834. doi:10.1128/JCM.00663-12. PMC 3421511. PMID 22649016 – via Pubmed.
  7. ^ Lopez, CE (Oct 2006). "Dimorphism and Pathogenesis of Histoplasma capsulatum". Revista Argentina de Microbiologia. 38 (4): 235–242. PMID 17370580 – via Pubmed.

External links[]


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