Histoplasma capsulatum polysaccharide antigen detection in diagnosis and management of disseminated histoplasmosis in patients with acquired immunodeficiency syndrome.

PURPOSE: Disseminated histoplasmosis is a serious and often rapidly progressive, opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS), supporting the importance of rapid diagnostic tests. We investigated Histoplasma capsulatum polysaccharide antigen (HPA) detection, a promising new method for rapid diagnosis of histoplasmosis. PATIENTS AND METHODS: Sixty-one cases of disseminated histoplasmosis in patients with AIDS form the basis of this report. Control cases were patients with AIDS who had other opportunistic infections and whose cultures were negative for H. capsulatum. A slightly modified radioimmunoassay procedure was used to measure the levels of HPA in urine and blood specimens.
RESULTS: High levels of HPA were detected in the urine of 59 of 61 (96.7%) and the blood of 37 of 47 (78.7%) patients with AIDS complicated by disseminated histoplasmosis. Treatment with amphotericin B reduced levels of HPA in the urine in 19 of 21 (90.5%) and the serum of all 10 patients tested. HPA levels increased in the urine in all eight and in the serum in all five patients with culture-proven relapse.
CONCLUSION: In conclusion, HPA detection offers a rapid method for diagnosing disseminated histoplasmosis. Additional experience is required to establish the role of this test in monitoring the effects of treatment and in identifying relapse in patients with AIDS.