Detection of antibodies to Candida albicans germ tube in the diagnosis of systemic candidiasis.

Sera from 109 subjects were tested for the presence of anti-Candida albicans antibodies by an indirect immunofluorescence assay. Aliquots of the sera were adsorbed with heat-killed blastospores to remove the antibodies against the surface of the yeast-phase cell wall and tested for anti-germ tube cell wall antibodies. Unadsorbed sera stained the entire cell wall of yeast and germ-tubes. Immunoglobulin G (IgG) antibodies were found in all patients with systemic candidiasis and in 81.2% of patients with Candida albicans isolated from skin and mucous membranes. IgA and IgG were found in 67.4 and 57.1%, respectively, of controls without evidence of candidiasis. After the adsorption only sera from patients with systemic candidiasis showed antibodies, predominantly IgA, against germ tube cell wall. Adsorption of the sera thus increased the specificity, efficiency, and positive and negative predictive values of the test. The test achieved the highest sensitivity in adsorbed sera for the combination of IgA and IgG.