''Chaetomium perlucidum'' is a neurotropic dematiaceous (melanated cell wall) fungus that is naturally found in the soil, including in agricultural soil, and in the stems of dead plants. The fungus can also be found on the feathers of birds, manure, seeds, and even paper. It is able to thrive at temperatures of . The fungus is an invasive

opportunist Opportunism is the practice of taking advantage of circumstances – with little regard for principles or with what the consequences are for others. Opportunist actions are expedient actions guided primarily by self-interested motives. The term ...

to humans that can cause diseases such as

onychomycosis Onychomycosis, also known as tinea unguium, is a fungal infection of the nail. Symptoms may include white or yellow nail discoloration, thickening of the nail, and separation of the nail from the nail bed. Toenails or fingernails may be affected ...

(fungus on nails), otolaryngologic (head and neck) or respiratory inflammations (like

sinusitis Sinusitis, also known as rhinosinusitis, is inflammation of the nasal mucosa, mucous membranes that line the paranasal sinuses, sinuses resulting in symptoms that may include thick Mucus#Respiratory system, nasal mucus, a nasal congestion, plugg ...

pneumonia Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severity ...

, and

empyema An empyema () is a collection or gathering of pus within a naturally existing anatomical cavity. For example, pleural empyema is empyema of the pleural cavity. It must be differentiated from an abscess, which is a collection of pus in a newly fo ...

), and brain

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...

History

It was first formally recorded in 1956 in Ukraine by K. S. Sergeeva.

Morphology

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

Perithecia (fruiting body)

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

Setae (bristle / "hair" structures)

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

Mature ascospores

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

Lipid / fatty acid composition

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

Pathogenicity

The fungus can cause chronic fungal infections in humans. 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.

Mode of transmission and infection

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

Susceptibility

There have been at least two reported cases of cerebral

phaeohyphomycosis Phaeohyphomycosis is a diverse group of fungal infections, caused by dematiaceous fungi whose morphologic characteristics in tissue include hyphae, yeast-like cells, or a combination of these. It can be associated an array of melanistic filamento ...

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

Treatment and prognosis

Most ''Chaetomium'' fungal diseases are without known cure and in one case of death from 1996, antifungal therapy through administering

Amphotericin B Amphotericin B is an antifungal medication used for serious mycosis, fungal infections and leishmaniasis. The fungal infections it is used to treat include mucormycosis, aspergillosis, blastomycosis, candida infections, candidiasis, coccidioidomy ...

(AMB) proved ineffective. AMB is a common and leading antibiotic treatment prescribed for fungal infections. 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 Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...

. However, the physical removal of a ''C. perlucidum'' growth through a

lobectomy Lobectomy means ''surgical excision of a lobe''. This may refer to a lobe of the lung (also simply called a lobectomy), a lobe of the thyroid (hemithyroidectomy), a lobe of the brain (as in anterior temporal lobectomy), or a lobe of the liver (h ...

(surgically removing the fungal growth from an area of affected organ/s) was successful in curing another patient from infection.

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. Optimal growth temperature however is at 37° C. Mature perithecia can be obtained if the fungus has access to a sterile plant source.

Occurrence in farming soil

''Chaetomium perlucidum'' was found more frequently in tilled than in untilled farmland.

References

{{Taxonbar, from=Q10447687 perlucidum Fungi described in 1956