Coccidioidomycosis is a respiratory infection that typically resolves rapidly. The mycosis can become acute, chronic, severe, or fatal. The disease may result in a chronic pulmonary condition or disseminate to the meninges, bones, joints, and subcutaneous and cutaneous tissues. The initial tissue response in rapidly disseminating disease is suppuration, whereas chronic and advancing infections are characterized by a granulomatous reaction with some areas being a mixed-type cellular response. It is believed that recovery results in immunity to reinfection. Approximately 60% of patients with primary infections are asymptomatic, 40% have mild to acute pulmonary disease and approximately 0.5% develop serious disease. About 25% of the patients with disseminated disease have meningitis.
Forms of the disease
Primary ( Pulmonary , Cutaneous), Secondary (
Pulmonary , Disseminated).
Prognosis and therapy
Primary coccidioidomycosis is treated with bed
rest and restricted activity. Steroids may be used to control allergic
reactions. Untreated secondary disease has a grave prognosis. The drug
of choice is amphotericin B. Meningitis usually requires intrathecal as
well as intravenous administration of amphotericin B. 5-Fluorocytosine
has little value in the treatment of cocidioidomycosis. Some patients treated
with miconazole have a high relapse rate. Itraconazole, Fluconazole and
Ketoconazole have also some value.
Histopathology
The tissue reaction is acute suppurative and
granulomatous inflammation. Acute suppuration is usually present around
the arthroconidia and after a spherule ruptures. Granulomatous inflammation
usually occurs around developing spherules. Hyphae may be present in pulmonary
cavities and meningeal lesions without arthroconidia, which can lead to
confusion wih the hyphae of an Aspergillus sp.
Laboratory
Direct examination of Clinical specimens, such
as fluids, sputa, and tissue, in 10% KOH may show Spherules 30-60 m in
diameter with a thick wall (up to 2 m) and endospores 2-5 m in diameter
characteristic of Coccidioides immitis. Endospores are released when the
wall of the spherule ruptures. Endospores that are no longer in a spherule
may remain closely appressed to each other, resulting in a potential confusion
with the yeast cells of Blastomyces dermatitidis. This is especially true
if the spherule wall is no longer visible and the clinical specimen has
been homogenized. . Isolation involves Inoculating the clinical material
onto IMA agar, BHI AGAR with 10%sheep blood and a medium containing cycloheximide
and incubate at 30° .Cultures should be kept 4 weeks before discarding
as negative. The fungus is fast growing and readily produces barrel-shaped
arthroconidia 2.5-4 x 3-6 m with a disjunctor cell between each arthroconidium.
Coccidioides immitis is a dangerous fungus and should be handled at all
times with due respect in a Class II or III biological safety cabinet.
Laboratory confirmation
Confirmation of C. immitis is required because
other fungi, such as members of the Gymnoascaceae, may develop an anamorph
similar to Coccidioides. In vitro procedures including special conversion
media, exoantigen procedure or DNA probes are available. Animal studies
may be necessary in some instances. Slide cultures should not be set up
when Coccidioides immitis is suspected due to its dangerous nature.
Causative agent
Coccidioides
immitis
Natural habitat
Alkaline soil of the Lower Sonoran Life Zone
in North, Central, and South America.
