Should we perform the serum cryptococcal antigen test in people living with HIV hospitalized due to a community-acquired pneumonia episode?

Abstract

Community-acquired pneumonia (CAP) is a common cause of hospitalization among people living with human immunodeficiency virus (PLWH), particularly those with severe immunosuppression. Pulmonary disease due to cryptococcosis is uncommonly reported and likely under-diagnosed. There is scarce information about cryptococcal antigen (CrAg) prevalence in PLWH with CAP. The objectives of this study were to identify among PLWH who were hospitalized with CAP: (i) the prevalence of serum CrAg positivity, (ii) the proportion with asymptomatic vs. symptomatic cryptococcosis; and (iii) the prevalence of serum CrAg positivity in CD4+ T-cell count <100 cells/mm3. We performed a sub-analysis of a prospective cohort of hospitalized adults enrolled into a randomized clinical trial testing therapy for CAP. We included 202 participants who had serum CrAg testing performed. We found a 3.5% prevalence of serum CrAg-positivity overall, being higher (5.7%) in CD4+ T-cell count <100 cells/mm3. Overall, asymptomatic and symptomatic cryptococcosis were present in 2.0% and 1.5%, respectively. This study identifies a target population for CrAg testing: PLWH hospitalized with diagnosis of CAP, particularly those with CD4+ T-cell count <100 cells/mm3 where the number needed to test was 18 to detect 1 CrAg-positive person. This approach may facilitate the detection of asymptomatic cryptococcal infection and allow a timely diagnosis of symptomatic cryptococcal disease.