Case 24 - Discussion

Uploaded: 2007-02-16, Updated: 2007-06-22
   
 

Coccidioidodes / Coccidioidomycosis

Taxonomic Classification
 

Kingdom: Fungi
Phylum: Ascomycota
Class: Euascomycetes
Order: Onygenales
Family: Onygenaceae
Genus: Coccidioides

Description and Natural Habitats
 

  • Two subgroups: Coccidioides immitis, and C. posadasii;

  • Thermally dimorphic fungi

  • In the United States, the endemic areas include southern Arizona, central California, Southern New Mexico, and west Texas.

Pathogenicity and Clinical Significance
 

  •  The causative agent of coccidioidomycosis in humans;

  • Cause systemic (endemic) mycoses by inhalation initially, and may later disseminate to other organs;

  • Spontaneous healing in about 95% the healthy hosts.

Forms of the disease
 

 

CATEGORIES

NOTES

Asymptomatic

  • Occurs in about 50% of patients

Acute Symptomatic

  • Pulmonary syndrome that combines cough, chest pain, shortness of breath, fever, and fatigue.

  • Diffuse pneumonia affects immunosuppressed individuals

  • Skin manifestations include fine papular rash, erythema nodosum, and erythema multiforme

  • Occasional migratory arthralgias and fever

Chronic Pulmonary

  • Affects between 5 to 10% of infected individuals

  • Usually presents as pulmonary nodules or peripheral thin-walled cavities

Extrapulmonary/Disseminated Varieties

Chronic skin disease

  • Keratotic and verrucose ulcers or subcutaneous fluctuant abscesses

Joints / Bones

  • Severe synovitis and effusion that may affect knees, wrists, feet, ankles, and/or pelvis

  • Lytic lesions commonly affecting the axial skeleton

Meningeal Disease

  • The most feared complication

  • Presenting with classic meningeal symptoms and signs

  • Hydrocephalus is a frequent complication

Others

  • May affect virtually any organ, including thyroid, GI tract, adrenal glands, genitourinary tract, pericardium, peritoneum

Microscopic Features
 

At 25°C

  • Hyphae: hyaline, septate and thin.  Arthroconidia:

  • Thick-walled, barrel-shaped, and 2-4 x 3-6 µm in size.

At 37°C

  • Large, round, thick-walled spherules (10-80 µm in diameter) filled with endospores (2-5 µm in diameter) are observed.

Reference
 

http://www.doctorfungus.org/thefungi/Coccidioides.htm