Immunodiffusion as a screening test for coccidioidomycosis serology

Abstract

Serum specimens were obtained on a routine basis from cases admitted to this hospital. These were tested for positive reactions in the complement fixation, precipitin, and immunodiffusion procedures using as antigen a toluene lysate preparation from pooled growth of strains of Coccidioides immitis . After completion of the tests, the results were compared and analyzed in conjunction with a review of the clinical records of the patients. Positive complement fixation results were obtained with specimens from 31 patients but a diagnosis of coccidioidomycosis was clinically valid in only 24 of these patients. Of the 24 significant positive complement fixation cases, 23 were also positive in the immunodiffusion test. The correlation between these two tests was demonstrated also in multiple specimens from each of 10 patients, since there was perfect agreement between the results of the two tests. In addition, of 402 cases with negative complement fixation, 401 were also negative in the immunodiffusion test. There was not sufficient evidence to indicate a similar correlation between the precipitin and immunodiffusion tests. It is recommended that the immunodiffusion and precipitin techniques be employed for routine serological testing for coccidioidomycosis. A positive result in either test should be followed with complement fixation studies.