Evaluation of five commercially available immunodiffusion kits for detection of Coccidioides immitis and Histoplasma capsulatum antibodies.

Five commercial test kits for the serodiagnosis of coccidioidomycosis and histoplasmosis based upon immunodiffusion were evaluated. The correlation of results with the test kits in the Clinical Laboratory varied from 71 to 100% for coccidioidomycosis. The correlation for coccidioidomycosis immunodiffusion testing varied from 57 to 83% when results from the test kits and the Mycology Research Laboratory were compared. Only 81% correlation was noted between the two laboratories when the same reference system was used. Results with the test kits for Histoplasma serodiagnosis and results from the Mycology Research Laboratory showed a correlation of 52 to 75%. There were no false-positive results with any system. All of the commercial kits were 100% specific for the diagnosis of both coccidioidomycosis and histoplasmosis, but the sensitivity of the immunodiffusion tests varied with the system used.