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Chaetomium atrobrunneum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Sordariomycetes
Order: Sordariales
Family: Chaetomiaceae
Genus: Chaetomium
Species:
C. atrobrunneum
Binomial name
Chaetomium atrobrunneum
Ames (1949)
Synonyms
  • Chaetomium fusisporale J.N. Rai & Mukerji (1962)
  • Chaetomium rectopilium Fergus & Amelung (1971)

Chaetomium atrobrunneum is a darkly pigmented mould affiliated with the fungal division, Ascomycota. [1] [2] [3] This species is predominantly saprotrophic, [2] although it has been known to infect animals including humans, showing a proclivity for the tissues of the central nervous system. [4] [5] Chaetomium atrobrunneum was described in 1949 from a mouldy military mattress cover obtained from the island of Guadalcanal. [6]

Growth and morphology

Chaetomium atrobrunneum is a darkly pigmented, predominantly mycelial fungus. [2] Colonies of C. atrobrunneum typically are dark grey to black in colour with a woolly appearance. [1] It forms sexual fruiting structures called perithecia that are spherical to oval in shape, [7] measuring between 70 and 150 μm in width when fully matured at 10 days. [1] The perithecia are covered sparsely with straight, finely-blistered, dark brown hairs that become occasionally become broadly branched with age. [1] [3] The perithecia contain asci within which are 8 ascospores that spindle-shaped, have a single sub-apical germ pore and are brown to grey in colour, [1] [3] although a mutant with colourless ascospores has been reported. [8] The ascospores of this species are smooth-walled and measure 9–11 μm in length by 4.5–6 μm in width. [1] [3]

Ecology and physiology

Chaetomium atrobrunneum has been reported from rabbit dung, [7] milled Italian rice, [9] water-damaged building materials, concrete, plaster and wallpaper. [10] Chaetomium atrobrunneum grows more slowly at 25 °C (77 °F) than most other species of the genus, [1] [3] reaching a colony diameter of 16–21 mm after 7 days incubation on Cornmeal Agar (CMA). [11] By contrast, its growth at higher temperatures is much more rapid than many other Chaetomium species, producing colonies of approximately 41–44 mm in diameter after 7 days incubation at 42 °C (108 °F) on CMA. [3] [11] Chaetomium atrobrunneum is distinct from other Chaetomium species by its smaller perithecia, its ability to grow at relatively high temperatures, [3] and the occasional presence in this taxon of perithecial hairs that branch at wide angles. [6]

Chaetomium atrobrunneum is strongly cellulolytic, [12] and cellulose-containing growth media can be used to selectively cultivate this and other Chaetomium species. [13] This species has also been reported to produce chaetoatrosin A, a selective inhibitor of chitin synthase II. This enzyme is involved in septum formation and cellular division, [14] and its inhibition by chaetoatrosin A is thought to be the mechanism underlying the antifungal effects of C. atrobrunneum culture filtrates against several medically important fungi including Cryptococcus neoformans. [14]

Pathogenicity

Chaetomium atrobrunneum is a rare pathogen of humans that tends to infect the tissues of the central nervous system. [1] Its pathogenicity is thought to be supported by its ability to grow at high temperatures. [1] [2] This species has been reported to be an agent of fatal brain abscesses in immunologically impaired people. [1] [3] [11] It can also cause systemic disseminated phaeohyphomycosis [5] affecting other organs including the lungs. [11] Infections due to this species have typically occurred following invasive procedures such as intravenous drug administration and renal transplantation. [11]

In addition to deep mycotic disease, C. atrobrunneum is known to eye diseases including retinitis [15] and keratitis, [16] manifesting with symptoms of pain, redness and watering of the eye, and swelling of the eyelid and surrounding tissues. [16] Corneal infections have responded to dual therapy with topical natamycin and oral ketoconazole. [16] This species has been reported from infections of the skin surrounding the eye. [17] Co-administration of the antifungal drugs fluconazole (delivered topically) and itraconazole (delivered orally) have been effective in the treatment of cutaneous disease. [17] Skin infections are thought to result from direct contact with environmental reservoirs of C. atrobrunneum such as soil, and accordingly farmers or children may have greater susceptibility. [17]

References

  1. ^ a b c d e f g h i j Barron, M.A.; Sutton, D.A.; Veve R.; Guarro J.; Rinaldi, M.; Thompson E.; Cagnoni P.J.; Moultney K.; Madinger N.E. (2003). "Invasive Mycotic Infections Caused by Chaetomium perlucidum, a New Agent of Cerebral Phaeohyphomycosis". Journal of Clinical Microbiology. 41 (11): 5302–5307. doi: 10.1128/jcm.41.11.5302-5307.2003. PMC  262481. PMID  14605190.
  2. ^ a b c d Liu, Dongyou (2011). Molecular Detection of Human Fungal Pathogens. Boca Raton, Florida: CRC Press. ISBN  9781439812419.
  3. ^ a b c d e f g h Howard, Dexter H. (2003). Pathogenic Fungi in Humans and Animals. New York, NY: Marcel Dekker Inc. ISBN  9780824706838.
  4. ^ Mukerji, K.G.; Manoharachary, C. (2010). Taxonomy and Ecology of Indian Fungi. New Delhi, India: I.K. International Publishing House. ISBN  9789380026923.
  5. ^ a b Paterson, R.M.; Lima, N. (2015). Molecular Biology of Food and Water Borne Mycotoxigenic and Mycotic Fungi. Boca Raton, Florida: CRC Press. ISBN  9781466559882.
  6. ^ a b Ames, L.M. (1949). "New Cellulose Destroying Fungi Isolated from Military Material and Equipment". Mycologia. 41 (6): 637–648. doi: 10.2307/3755020. JSTOR  3755020.
  7. ^ a b Ellis M.B.; Ellis J.P. (1998). Microfungi on Miscellaneous Substrates: An Identification Handbook. Slough, England: The Richmond Publishing Co. Ltd. ISBN  0855462485.
  8. ^ Udagawa, SI; Takada, M (1968). "Notes on some Japanese Ascomycetes VII". Nippon Kingakukai Kaiho. 22: 43–49.
  9. ^ Seth, Hari K. (1970). "A monograph of the genus Chaetomium". Nova Hedwigia. Beihefte. 37. Germany: J. Cramer: 133 pp.
  10. ^ Anderson, B.; Frisvad J.C.; Sondergaard I.; Rasmussen I.S.; Larsen L.S. (2011). "Associations between Fungal Species and Water-Damaged Building Materials". Applied and Environmental Microbiology. 77 (12): 4180–4188. doi: 10.1128/aem.02513-10. PMC  3131638. PMID  21531835.
  11. ^ a b c d e Abbott, S.P.; Sigler, L.; McAleer, R.; McGough, D.A.; Rinaldi, M.G.; Mizell, G. (1995). "Fatal Cerebral Mycoses Caused by the Ascomycete Chaetomium strumarium". Journal of Clinical Microbiology. 33 (10): 2692–8. doi: 10.1128/JCM.33.10.2692-2698.1995. PMC  228557. PMID  8567907.
  12. ^ Siu, R.G.H. (1951). Microbial decomposition of cellulose. New York: Reinhold.
  13. ^ Atlas, R.M. (2010). Handbook of Microbiological Media (Fourth ed.). Boca Raton, Florida: CRC Press. ISBN  9781439804063.
  14. ^ a b Hwang E.I.; Yun B.S.; Kim Y.K.; Kwon B.M.; Kim H.G.; Lee H.B.; Bae K.S.; Kim S.U. (2000). "Chaetoatrosin A, a Novel Chitin Synthase II Inhibitor Produced by Chaetomium atrobrunneum F449". The Journal of Antibiotics. 53 (3): 248–55. doi: 10.7164/antibiotics.53.248. PMID  10819295.
  15. ^ Tabbara, Khalid F.; Wedin, Keith; Al Haddab, Saad (2010). "Chaetomium Retinitis". Retinal Cases & Brief Reports. 4 (1): 8–10. doi: 10.1097/ICB.0b013e31819b19b3. PMID  25390107.
  16. ^ a b c Balne P.K.; Nalamada S.; Kodiganti M.; Taneja M. (2012). "Fungal Keratitis Caused by Chaetomium atrobrunneum". Cornea. 31 (1): 94–95. doi: 10.1097/ico.0b013e31821eeaed. PMID  22045390. S2CID  34409097.
  17. ^ a b c Zhang, H.; Ran, Y.; Li, D.; Liu, Y.; Xiang, Y.; Zhang, R.; Dai, Y. (2010). "Clavispora lusitaniae and Chaetomium atrobrunneum as Rare Agents of Cutaneous Infection". Mycopathologia. 169 (5): 373–380. doi: 10.1007/s11046-009-9266-9. PMID  20020214. S2CID  24845050.

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