Dimorphic fungi

Dimorphic fungi are able to grow in two stages: up to 30 ° C, the fibrous form grows, and at 35-37°C the yeast form grows. Both forms are the cause of infections penetrating mucous membranes and skin, and the yeast form also causes systemic infections.

Cultivation

The growth of dimeric fungi is slow, not blocked by cycloheximide which is added to the culture medium. Hyphae are fibrous forms, fine, arranged in parallel. It is also possible to provoke a change from one phase to another.

Proof

We demonstrate dimorphic fungi indirectly, most often by ELISA, double immunodiffusion or complement fixation reaction.

Shortcuts

Dimorphic fungi include several representatives: Histoplasma, Blastomyces, Coccidioides, Sporothrix or Penicillium marneffei .

Blastomyces

The main representative is B. blastomycosis-causing dermatitis, belonging to endemic diseases (the USA, along the Mississippi, southern Canada).

A fibrous form grows in the soil, which enters the body by inhalation of dust with conidia, and therefore always causes primary lung disease. Dissemination and secondary impairment manifest themselves in immunocompromised individuals.

More often, however, there are skin forms that enter the body through injured skin.

Histoplasma

H. capsulatum occurs along major rivers in the United States. There are 3 varieties: capsulatum, dubosii (Africa) and farcinimosum, which causes equine and mule lymphadenitis and is therefore epizootic. The overall diseases are the same as in Blastomyces.

Coccidioides

C. immitis occurs in the USA. Requires shorter cultivation than other dimorphic fungi. The fibrous form breaks down into highly infectious arthroconidia and is the cause of laboratory infections. It causes coccidioidomycosis, which manifests itself differently in immunocompromised people and people infected with AIDS. In individuals with weakened immunity, it is asymptomatic in 60%, in 2% it turns into a chronic form. AIDS-infected individuals have a primary lung injury with coughing up purulent sputum.

Penicillium marneffei

Penicillium spp. is one of the filamentous fungi that grows rapidly and resembles a brush (hence the name brush mould).

P. marneffei is pathological to humans. This is the first species that is able to cause infection, especially in individuals infected with AIDS (lungs, liver, skin). The reservoir is bamboo rats in Laos, Thailand, Vietnam. It is a dimorphic fungus because it forms single-celled yeast-like formations in the affected tissue. Their conidia worsen the condition of allergy sufferers and asthmatics.

Links

Related articles

• Overview of fungal intoxication
• Candidosis
• Dermatomycoses

Sources

• VOTAVA, Miroslav. Lékařská mikrobiologie speciální. 1. edition. 2003. ISBN 80-902896-6-5.

• BEDNÁŘ, Marek – SOUČEK, Andrej – FRAŇKOVÁ, Věra. Lékařská mikrobiologie : Bakteriologie, virologie, parazitologie. 1. edition. 1996. ISBN 8023802976.