The Clinical Usefulness of Fungal Serologic Testing

¹ Senior Resident in Internal Medicine
² Chief, Pulmonary Disease Service
³ Chief, Microbiology Division, USAMRNL

During a three-year period at Fitzsimons General Hospital, 2,928 complement fixation tests were performed on the sera of 2,100 patients, using the antigens of Coccidioides immitis, Histoplasma capsulatum, and Blastomyces dermatitidis. One hundred eleven patients had titers of 1:8 or above to one or more of these fungal antigens. The records of 102 of these patients were studied retrospectively. Final diagnoses were as follows: tuberculosis, 47 cases; histoplasmosis, 22 cases; coccidioidomycosis 10 cases; and other nonfungal, nontuberculous, predominantly pulmonary diseases, 23 cases. A presumptive diagnosis of fungal disease could often be based upon skin tests and serologies. Higher titered serologies and the stronger positive skin tests were related to the homologous disease. Tuberculosis was bacteriologically proved in 79 per cent of cases with that diagnosis, and generally had low or transient fungal complement fixation titers, except when related temporally to previous fungal skin testing. Positive complement fixation tests for fungal disease, regardless of titer, are worthwhile screening devices in the diagnosis of pulmonary disease.