Evaluation of a commercial <i>Histoplasma</i> antigen detection enzyme immunoassay for the follow-up of histoplasmosis treatment in people living with HIV from Argentina

Histoplasmosis poses a significant risk to HIV patients, particularly in regions with limited access to antiretroviral therapy. Antigen detection assays are crucial in these settings for timely diagnosis and treatment, which can reduce mortality. While commercial antigen detection kits have performed well in diagnosing histoplasmosis, their effectiveness in monitoring treatment remains unclear. This study aimed to evaluate the correlation between urine antigen levels and clinical response using the clarus Histoplasma Galactomannan (GM) enzyme immunoassays (EIA) kit. The study followed 27 HIV patients diagnosed with histoplasmosis over 24 weeks, measuring urinary Histoplasma antigen (Ag) levels and clinical outcomes. Patients received amphotericin B as induction therapy, followed by maintenance with itraconazole. Results showed a significant decrease in Ag levels over time, with clinical scores improving in correlation with the decline in Ag levels. Four patients exhibited atypical Ag patterns due to immune reconstitution inflammatory syndrome or issues with itraconazole bioavailability. Despite these challenges, all patients showed improvement by week 24. The findings suggest that the clarus Histoplasma GM EIA kit could be a valuable tool for monitoring and evaluating the response to antifungal therapy in histoplasmosis patients.