Characteristics and Outcomes of Hospitalized Patients with Histoplasmosis: Comparison of Immunocompromised and Non-Immunocompromised Adult Patients

We sought to investigate the role of immunocompromise in patients with newly diagnosed histoplasmosis in an era when AIDS is less prevalent. We performed a retrospective comparison of immunocompromised and non-immunocompromised adults hospitalized at Michigan Medicine from 2015 to 2024. Of 51 patients, 37 (73%) were immunocompromised, 32 from solid organ transplantation or tumor necrosis factor antagonist/disease-modifying anti-rheumatic drugs. Of these 37, 34 had disseminated and 3 had pulmonary histoplasmosis; of the 14 non-immunocompromised patients, 8 had disseminated and 6 had pulmonary histoplasmosis, <i>p</i> = 0.004. Fever was the only symptom/sign that was more common in the immunocompromised cohort (86% vs. 36%, <i>p</i> = 0.003). Laboratory/radiological studies showed no major differences between immunocompromised and non-immunocompromised cohorts. <i>Histoplasma</i> urinary antigen was positive for all immunocompromised vs. 79% non-immunocompromised patients, <i>p</i> = 0.003. Median antigen levels were 17.5 (IQR 6.2-19.7) ng/mL for immunocompromised vs. 1.9 (0.6-19.7) ng/mL for non-immunocompromised patients, <i>p</i> = 0.004. Cultures for <i>Histoplasma</i> were more often positive in the immunocompromised cohort, <i>p</i> = 0.025. All-cause 90-day mortality was 14% in each cohort (five immunocompromised and two non-immunocompromised patients); all deaths occurred in those with disseminated histoplasmosis, and four were in the first week of hospitalization. Disseminated histoplasmosis in both immunocompromised and non-immunocompromised patients continues to be a serious, often fatal infection.