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

Community-acquired pneumonia (CAP) is a common cause of hospitalization among people living with HIV/AIDS (PLWHA), particularly those with severe immunosuppression. Pulmonary disease due to cryptococcosis is uncommonly reported and likely under-diagnosed. There is scarce information cryptococcal antigen (CrAg) prevalence in PLWHA with CAP. The objectives of this study were to identify among PLWHA 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 randomized clinical trial testing therapy for CAP. We included 202 participants who had a serum CrAg testing performed. We found a 3.5% prevalence of serum CrAg-positivity overall, being higher (4.8%) in CD4+ T-cell count <100 cells/mm3. Asymptomatic and symptomatic cryptococcosis was present in 2.0% and 1.5% overall, respectively. This study identifies a target population for CrAg testing: PLWHA 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.