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School of Molecular & Biomedical Science
The University of Adelaide
AUSTRALIA 5005

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Dr David Ellis
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Paracoccidioidomycosis

Description:

Paracoccidioidomycosis is a chronic granulomatous disease that characteristically produces a primary pulmonary infection, often inapparent, and then disseminates to form ulcerative granulomata of the buccal, nasal and occasionally the gastrointestinal mucosa. The disease in its inception and development is similar to blastomycosis and coccidioidomycosis. The only etiological agent, Paracoccidioides brasiliensis is geographically restricted to areas of South and Central America.

Clinical manifestations:

Clinical manifestions vary from subclinical infections that are detected only by skin-test positivity; to chronic unifocal infection where only a single organ is involved; to chronic multifocal infection where more than one organ is involved. A subacute juvenile infection is also recognised.

Pulmonary paracoccidioidomycosis: Most cases have an indolent onset and patients present with chronic symptoms such as cough, fever, night sweats, malaise and weight loss. Chest x-rays are characteristic but not diagnostic. The infection must be distinguished from histoplasmosis and tuberculosis.

Mucocutaneous paracoccidioidomycosis: The mouth and nose are the most usual mucosal sites of infection. Painful ulcerated lesions develop on the gums, tongue, lips or palate and can progress over weeks or months. Perforation of the palate or nasal septum may occur. Cutaneous lesions often appear on the face around the mouth and nose, although patient with severe infection can have widespread lesions.

destruction of facial features
Mucocutaneous paracoccidioidomycosis showing extensive destruction of facial features.

ulcerated lesion
Mucocutaneous paracoccidioidomycosis showing an ulcerated lesion on the pharyngeal mucosa.

Lymphonodular paracoccidioidomycosis: Lymphadenitis is common in younger patients. Cervical and submandibular chains are the most obvious manifestation and lymph nodes may progress to form abscesses with draining sinuses.

Disseminated paracoccidioidomycosis: Haematogenous spread of P. brasiliensis can resulkt in widespread disseminated disease; including lesions of the small or large intestine, hepatic lesions, adrenal gland destruction, osteomyelitis, arthritis, endophthalmitis and meningoencephalitis or focal cerebral lesions.

Laboratory diagnosis:

1. Clinical material: Skin scrapings, sputum and bronchial washings, cerebrospinal fluid, pleural fluid and blood, bone marrow, and tissue biopsies from various visceral organs.

2. Direct Microscopy: (a) Skin scrapings should be examined using 10% KOH and Parker ink or calcofluor white mounts; (b) Exudates and body fluids should be centrifuged and the sediment examined using either 10% KOH and Parker ink or calcofluor white mounts, (c) Tissue sections should be stained using PAS digest, Grocott's methenamine silver (GMS) or Gram stain.

Histopathology is especially useful and is one of the most important ways of alerting the laboratory that they may be dealing with a potential pathogen.

GMS stained lung section phase contrast of cells from a culture
Multiple, narrow base, budding yeast cells "steering wheels" of P. brasiliensis. GMS stained lung section (left) and phase contrast of cells from a culture (right).

Interpretation: As a rule, a positive direct microscopy demonstrating the presence of large, 20-60 um, round, narrow base budding yeast cells with multiple budding "steering wheels" from any specimen should be considered significant.

3. Culture: Clinical specimens should be inoculated onto primary isolation media, like Sabouraud's dextrose agar and Brain heart infusion agar supplemented with 5% sheep blood.

Interpretation: A positive culture from any of the above specimens should be considered significant.

4. Serology:

5. Identification: Clinical history, tissue pathology, culture identification with conversion to the yeast phase at 37C are important characters.

Causative agents:

Paracoccidioides brasiliensis

Treatment Guidelines

 

Further reading:

Ajello L and R.J. Hay. 1997. Medical Mycology Vol 4 Topley & Wilson's Microbiology and Infectious Infections. 9th Edition, Arnold London.

Kwon-Chung KJ and JE Bennett 1992. Medical Mycology Lea & Febiger.

Richardson MD and DW Warnock. 1993. Fungal Infection: Diagnosis and Management. Blackwell Scientific Publications, London.

Rippon JW. 1988. Medical Mycology WB Saunders Co