Home | | Microbiology and Immunology | Paracoccidioidomycosis

Chapter: Microbiology and Immunology: Mycology, Fungi: Systemic Mycoses

Paracoccidioidomycosis

Paracoccidioidomycosis, also known as South American blastomycosis and Lutz–Splendore–Almeida disease, is a chronic progressive systemic mycosis caused by Paracoccidioidesbrasiliensis. P. brasiliensis is a thermally dimorphic fungus foundin the soil.

Paracoccidioidomycosis

Paracoccidioidomycosis, also known as South American blastomycosis and Lutz–Splendore–Almeida disease, is a chronic progressive systemic mycosis caused by Paracoccidioidesbrasiliensis. P. brasiliensis is a thermally dimorphic fungus foundin the soil. It occurs as a mold in the soil and as a yeast in tis-sue. These yeasts are unique in that one large mother cell pro-duces multiple blastoconidia (daughter cells) that arise from multiple sites, resembling a “Mickey Mouse head” or a “pilotwheel.” This characteristic appearance helps to differentiatethis yeast from Blastomyces dermatitidis and all other yeasts.

Infection occurs by inhalation of conidia or mycelial frag-ments. The lungs are the primary site of infection. From this site, the fungus then disseminates to other organs through the venous and lymphatic systems. Cell-mediated immu-nity (CMI) is the most important defense mechanism in an immunocompetent host. However, most initial infections are subclinical.

In adults, the course of disease is long-term and the outcome is better with appropriate therapy. Pulmonary infection is the most common manifestation. The disease in younger patients is subacute and carries a worse prognosis.

Paracoccidioidomycosis has a restricted geographical distri-bution. It is found in South and Central America. The highest incidence is in the southeast province of Brazil, followed by Colombia, Venezuela, Ecuador, and Argentina.

P. brasiliensis causes natural infection only in armadillos. Batsand saguis may serve as reservoirs. The infection is transmitted by inhalation of conidia or mycelial fragments that are found in the soil. Direct inoculation of the skin or oral mucous membranes is uncommon. However, it may occur from the use of twigs to clean teeth, which is commonly practiced in rural Brazil. The infection can also be transmitted orally by ingestion. Person-to-person transmission does not occur.

Laboratory diagnosis depends on demonstration of large, multiple budding yeasts (blastoconidia) in 30% KOH wet mount preparation of sputum. Gomori’s methenamine silver (GMS) staining of biopsy specimens shows yeast cells mea-suring 2–30 mm in diameter. Tissue reactions are diffuse in the juvenile form, while granuloma formation is typical in the adult form. The organism is isolated by culture on SDA at 37°C after 20–30 days.

    Itraconazole is the drug of choice for treatment of para-coccidioidomycosis and is effective in 95% of patients. Imidazole is also an effective agent with a cure rate of 85–90%. Amphotericin B is used as a reserve for treatment of severe cases that are refractory to treatment with these drugs.


Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail
Microbiology and Immunology: Mycology, Fungi: Systemic Mycoses : Paracoccidioidomycosis |


Privacy Policy, Terms and Conditions, DMCA Policy and Compliant

Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.