habitat of Paracoccidioides remains unknown, although it has been
isolated only on a few occasions from non – medical sources, primarily
from humid soil rich in proteins and from the digestive tract of some
animals. It has been cultivated from fruit bats and armadillos.
Paracoccidioides is a thermally
dimorphic fungus. Its geographic
distribution is restricted to South America where the majority of cases
have been reported, particularly from Brazil, Venezuela, and Colombia.
Recently, through random amplified polymorphic DNA analysis, the
geographic discrimination of the strains has been made possible.
Paracoccidioides contains only one species, Paracoccidioides
brasiliensis. Paracoccidioides brasiliensis is an anamorphic
fungus and has no known teleomorph.
Pathogenicity and Health Effects
the etiologic agent of a true systemic mycosis called
paracoccidioidomycosis. The range of infection of this chronic illness is
wide, varying from an asymptomatic infection or progression in the form of
a pulmonary or disseminated infection which is characterized by formation
of secondary lesions of the buccal, nasal or gastrointestinal mucosa and
may also be infected are the lymph nodes and aortitis may develop.
Diagnosis of paracoccidioidomycosis is often complicated. The infection
may become evident several years after exposure to Paracoccidioides
brasiliensis thus, suggesting the likelihood of a long latent period.
This chronic illness is acquired via inhalation of the conidia, followed
by primary infection of the lungs. The extent of pathogenicity may differ
and appears strain – dependent. The fungal exocellular enzyme called
serine – thiol proteinase is a significant virulence factor for tissue
invasion. Acute pulmonary and disseminated paracoccidioidomycosis may
rarely develop in immunocompromised patient. Given the true systemic
nature of paracoccidioidomycosis, otherwise healthy individuals are
grows in mold form at 25°C
and in its yeast
form at 37°C due to its characteristic of being a thermally dimorphic
25°C, the colonies are glabrous and velvety, slow – growing, with
diameter ranging from 1 – 2 cm within two to three weeks, the surface
color is white, tan or brown while the reverse is yellowish brown to
37°C, the colonies are yeast – like with creamy texture, white in color,
heaped, wrinkled or folded; and
Enriched medium such as brain heart infusion agar supports mold to yeast
conversion within ten to twenty days of incubation.
25°C, formation of hyaline septate hyphae which are sterile and do not sporulate and the
conidia produced are oval – shaped, unicellular,
truncate, with a broad base and rounded tip, and are found along the
37°C, formation of daughter cells which are attached to the mother cell by
narrow neck portion which resembles a steering wheel and secondary cells
in short chains are formed before the detachment of the original daughter
cells from the mother cell.
Paracoccidioides brasiliensis must be handled with caution in a
biological safety cabinet, even though, most strains are sterile and do
There are limited
in vitro data on susceptibility activity of Paracoccidioides
brasiliensis. Reference method is not standardized as yet and the
methods that have been employed for susceptibility analysis also vary
thus, meaningful comparisons are difficult to obtain. Generally,
amphotericin B, ketoconazole, itraconazole, fluconazole, and voriconazole
relatively yielded low MICs against the yeast phase of Paracoccidioides
brasiliensis. However, higher itraconazole and fluconazole values
have been reported for some isolates in another study. Additionally,
cilofungin provided high MICs. Itraconazole now emerges as the drug of
choice for treatment of paracoccidioidomycosis aside from amphotericin B,
sulphonamides, and ketoconazole.