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 of 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.