Rapid diagnosis of coccidioidomycosis by nested PCR assay of sputum.

Coccidioidomycosis is a deep infection caused by two dimorphic fungi, Coccidioides immitis and Coccidioides posadasii. Diagnosis of the disease requires culture of suspicious clinical samples on mycological media. However, as these species are virulent pathogens, handling of their cultures is a high-risk activity, and is limited to Biosafety Level 3 laboratories. This study describes the direct detection of C. posadasii DNA in an inappropriate sputum sample by PCR amplification of the highly specific Ag2/PRA antigen gene. The results obtained suggest that direct detection of the Ag2/PRA sequence in sputum is an excellent method for rapid and specific diagnosis of coccidioidomycosis.