Latex agglutination tests for detection of Candida antigens in sera of patients with invasive candidiasis.

The utility of two latex agglutination tests in detecting antigenemia in patients with invasive candidiasis was studied. To perform one test, we treated sera with protease and heat to free mannan from antibodies to mannan. Latex beads coated with antibodies to mannan detected mannan in supernatants. In the second test, untreated sera were tested for capacity to agglutinate a commercially available preparation of latex beads coated with antibody to Candida. Two panels of sera were analyzed with the tests. One comprised 355 sera sequentially collected from 75 leukemic patients who underwent 97 episodes of chemotherapy resulting in neutropenia. The other panel comprised 364 sera collected only at the time candidiasis was suspected from 150 patients with a variety of underlying diseases. Of 23 episodes of invasive candidiasis in leukemic patients, antigenemia was detected in 18 (78%) by the mannan latex agglutination test and in 11 (48%) by the commercial test. For the second serum panel the respective tests detected antigenemia in only 22% and 19% of patients with invasive candidiasis. While latex agglutination tests for circulating Candida antigens may be useful for diagnosing invasive candidiasis, the transient nature of antigenemia requires frequent testing of patients' sera and limits the usefulness of the tests in diagnosing invasive candidiasis.