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Fungal Infections

Species name/ common name

Paracoccidioides brasiliensis (teleomorph: unknown; read review by Gow et al) and Paracoccidioides lutzii.

P. lutzii appears to be a single species, but P. brasiliensis is a complex of 4 cryptic species.

Natural habitat

Unknown, but in agricultural/forest environment.

Geography

Central and South America.

Frequency

Important mycosis in tropical areas of American continent with temperatures between 1ºC to 30ºC, altitude below 2,000 m and acidic soils. Few studies have been performed to know the real prevalence of the infection. Although it is variable, it seems that Brazil has the highest annual incidence estimated in 1 to 3 cases per 10,000 inhabitants. Other countries where the infection is frequently diagnosed are Argentina, Colombia, Ecuador, and Venezuela. Much more frequent in males, with a male female ration of ~20:1.

Diseases

Agent of paracoccidioidomycosis. Systemic chronic disease. It can affect inmunocompetent patients although the infection becomes more aggressive in inmunocompromised hosts. Produces initially a pulmonary infection and then disseminates to different parts of the body, including mouth and gums, lymph nodes.

Culture peculiarities

Macroscopy and microscopy are not very characteristic. The most striking characteristic is its dimorphism thermally driven. At 37ºC, a yeast-like form is produced whereas at 25ºC is a filamentous fungus. At 37ºC the colonies is white or cream with variable texture. Spherical cell produce piriform microconidia by synchronous budding forming the characteristic “steering wheels” of this fungus. At 25ºC slowly growing mycelial phase is developed with white to brownish colonies. Microscopically. Conidia are usually absent, intercalary chlamydospores cells might be present. If seen, conidia may show a  'bicorn cocked hat’ appearance and barrel-shaped conidia are common to both species, P. lutzii frequently produces elongated, rod-shaped conidia, which sufficiently distinctive to be used for species diagnosis. The best way to identify this species is by sequencing the ITS fragment.

Antifungal resistance (intrinsic and acquired)

Due to its slow growth and dimorphism, there is not an appropriate methodology to measure the resistance in the laboratory. It is not known if unresponsive cases are due to host’s background or resistance to antifungals.

Biosafety level 3

This fungal species must be managed in a laboratory with safety containment level 3.

Industrial use

None

Link 
Paracoccidioides brasiliensis the man hater Mycologist 2002

Images

Paracoccidioides brasiliensis
Colony appearance of Paracoccidioides brasiliensis on mycobiotic agar at 26◦C for 20 days.


Highly characteristic appearance of P. brasiliensis in tissue, showing the ‘ship’s wheel’ appearance, not seen in any other infection.( Kindly supplied by Prof Dr Luiz Cosme Cotta Malaquias)

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