Chaetomium perlucidum

Chaetomium perlucidum is a neurotropic[3] dematiaceous (melanated cell wall)[4] fungus that is naturally found in the soil,[5] including in agricultural soil,[6] and in the stems of dead plants.[7] The fungus can also be found on the feathers of birds, manure, seeds, and even paper.[3] It is able to thrive at temperatures of 35 and 42 °C (95 and 108 °F).[3]

Chaetomium perlucidum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Sordariomycetes
Order: Sordariales
Family: Chaetomiaceae
Genus: Chaetomium
Species:
C. perlucidum
Binomial name
Chaetomium perlucidum
Sergeeva (1956)
Synonyms
  • Chaetomium perlucidum Sergeeva [1]
  • Chaetomium perlucidum Sergeeva 1956 [2]
  • Chatomium perlucidum [2]

The fungus is an invasive opportunist[3][4] to humans that can cause diseases such as onychomycosis (fungus on nails), otolaryngologic (head and neck) or respiratory inflammations (like sinusitis, pneumonia, and empyema), and brain necrosis.[3]

History

It was first formally recorded in 1956 in Ukraine by K. S. Sergeeva.[1][8]

Morphology

Chaetomium perlucidum is pigmented and dark in colour, appearing hairy and wooly, with a growth rate of 4-5 mm/day.[3]

Perithecia (fruiting body)

Chaetomium perlucidum's fruiting bodies become fully mature in 13-16 days.[3] The fruiting body's structural width is 90-200 μm, with an ostiolar pore (open pore) width of 30-50 μm.[3]

Setae (bristle / "hair" structures)

Setae width is 2-3 μm and can have lengths of up to 700 μm.[3] The setae are unbranched and appear to undulate.[3]

Mature ascospores

Fully mature ascospores are 12.5-14 μm x 6-7.5 μm in size.[3] They are smooth, oval-shaped, and brown in colour.[3]

Lipid / fatty acid composition

Chaetomium perlucidum is composed of saturated, monounsaturated, and polyunsaturated fatty acids.

C. perlucidum fatty acid content[9]
Fatty acid Amount (%)
Pentadecylic acid / pentadecanoic acid (15:0, CH3(CH2)13COOH) 0.42 ± 0.33
Palmitic acid / hexadecanoic acid (16:0, C16H32O2) 18.95 ± 0.92
Palmitoleic acid (16:1, C16H30O2) trace amounts
Stearic acid / octadecanoic acid (18:0, C18H36O2) 6.76 ± 0.45
Oleic acid (18:1, CH3(CH2)7CH=CH(CH2)7COOH) 7.38 ± 5.79
Linoleic acid (18:2, C18H32O2) 63.48 ± 3.71

Pathogenicity

The fungus can cause chronic fungal infections in humans.[3][10] An infection can spread throughout the body from a single point of infection into various other systems, e.g., the central nervous, cardiovascular, respiratory, and immune systems, with especially a low prognosis for cerebral infections.[3]

Mode of transmission and infection

Infections take hold in the brain and progress to spread throughout the body.[3] Pathways of entry into the host's body include via cutaneous lesions, oral intake, or intravenously.[3]

Susceptibility

There have been at least two reported cases of cerebral phaeohyphomycosis in humans with one case resulting in death, reported in 2003.[3] Both cases occurred in immunosuppressed individuals already suffering from complications of other unrelated diseases.[3] Recreational drug users, or patients who have undergone intravenous or transplant procedures at even hospitals are also susceptible to being infected by C. perlucidum.[3]

Treatment and prognosis

Most Chaetomium fungal diseases are without known cure[3] and in one case of death from 1996, antifungal therapy through administering Amphotericin B (AMB) proved ineffective.[11] AMB is a common and leading antibiotic treatment prescribed for fungal infections.[12] In one case, C. perlucidum infection in the brain caused death from hemorrhaging throughout the body (especially in the brain) and complications that arose from acute inflammation.[3] However, the physical removal of a C. perlucidum growth through a lobectomy (surgically removing the fungal growth from an area of affected organ/s) was successful in curing another patient from infection.[3]

Culturing techniques

Chaetomium perlucidum ascospores can be cultured and grown in the lab through incubation on potato flake agar at 25°C for 6-10 days.[3] Optimal growth temperature however is at 37°C.[3] Mature perithecia can be obtained if the fungus has access to a sterile plant source.[3]

Occurrence in farming soil

Chaetomium perlucidum was found more frequently in tilled than in untilled farmland.[13]

References
  1. Chaetomium perlucidum Sergeeva. GBIF.
  2. Chaetomium perlucidum Sergeeva 1956. Uniprot.
  3. 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. ISSN 0095-1137. PMC 262481. PMID 14605190.
  4. Phaeohyphomycosis - Infectious Diseases. Merck Manuals Professional Edition.
  5. Ahmed, S. A.; Khan, Z.; Wang, X.; Moussa, T. A. A.; Al-Zahrani, H. S.; Almaghrabi, O. A.; Sutton, D. A.; Ahmad, S.; Groenewald, J. Z.; Alastruey-Izquierdo, A.; van Diepeningen, A. (2016). "Chaetomium-like fungi causing opportunistic infections in humans: a possible role for extremotolerance". Fungal Diversity. 76: 11–26. doi:10.1007/s13225-015-0338-5. ISSN 1878-9129.
  6. Aggarwal, R.; Sharma, V.; Kharbikar, L. L. (2008). "Molecular characterization of Chaetomium species using URP-PCR". Genetics and Molecular Biology. 31 (4): 943–946. doi:10.1590/s1415-47572008005000014. ISSN 1415-4757.
  7. Index Fungorum - Names Record. Index Fungorum.
  8. Chaetomium perlucidum. Mycobank.
  9. Stahl, P. D.; Klug, M. J. (1996). "Characterization and Differentiation of Filamentous Fungi Based on Fatty Acid Composition". Applied and Environmental Microbiology. 62 (11): 4136–46. Bibcode:1996ApEnM..62.4136S. doi:10.1128/aem.62.11.4136-4146.1996. PMC 1388980. PMID 16535442.
  10. Chhonkar, A.; Kataria, D.; Tambe, S.; Nayak, C. S. (2016). "Three rare cases of cutaneous phaeohyphomycosis". Indian Journal of Plastic Surgery. 49 (2): 271–274. doi:10.4103/0970-0358.191321. ISSN 0970-0358. PMC 5053006. PMID 27833296.
  11. Yeghen, T.; Fenelon, L.; Campbell, C. K.; Warnock, D. W.; Hoffbrand, A. V.; Prentice, H. G.; Kibbler, C. C. (1996). "Chaetomium pneumonia in patient with acute myeloid leukaemia". Journal of Clinical Pathology. 49 (2): 184–186. doi:10.1136/jcp.49.2.184. ISSN 0021-9746. PMC 500362. PMID 8655695.
  12. Torrado, J. J.; Espada, R.; Ballesteros, M. P.; Torrado-Santiago, S. (2008). "Amphotericin B Formulations and Drug Targeting". Journal of Pharmaceutical Sciences. 97 (7): 2405–2425. doi:10.1002/jps.21179. ISSN 0022-3549. PMID 17893903.
  13. Sharma-Poudyal, D.; Schlatter, D.; Yin, C.; Hulbert, S.; Paulitz, T. (2017). "Long-term no-till: A major driver of fungal communities in dryland wheat cropping systems". PLOS ONE. 12 (9): e0184611. Bibcode:2017PLoSO..1284611S. doi:10.1371/journal.pone.0184611. ISSN 1932-6203. PMC 5595340. PMID 28898288.
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