False-positive reactions of cerebrospinal fluid and diluted sera with the coccidioidal latex-agglutination test.

Most samples of cerebrospinal fluid from 49 patients with or without coccidioidomycosis yielded positive agglutination with the Hyland ("CM") latex-particle agglutination test. Furthermore, simple dilution of sera from patients with or without coccidioidomycosis yielded a strong agglutination reaction with the latex particle agglutination test reagent. These reactions were found with three lots of the latex-particle agglutination test reagent. One lot latex particles was found to give agglutination reactions merely by addition of saline solution or water, though a second lot did not. It is advisable, therefore, that the latex-particle agglutination test not be applied to cerebrospinal fluid, and that it be applied cautiously, particularly with diluted sera.