Impact of pneumococcal urinary antigen testing on clinical outcomes in patients hospitalized with community-acquired pneumonia

To establish a microbiological etiology in severe community-acquired pneumonia (CAP), most guidelines recommend adding urinary antigen tests (UAT) to respiratory sampling. However, their usage and impact remain unclear. We examined the clinical impact of UAT in hospitalized CAP patients. This multicenter cohort study included patients admitted with CAP at three hospitals in Denmark from 2017 to 2020. Logistic regression and propensity-score matching were applied to assess the effect of UAT on 30-day mortality, targeted antibiotic treatment and atypical antibiotic coverage. Propensity-score matching was applied to adjust for confounding. Of 2,449 patients included, 654 (27%) had UAT performed within 48 hours of admission. Streptococcus pneumoniae was detected in 8.0% (52/654). 30-day mortality was 11.8% in the tested group and 10.2% in the untested group (adjusted odds ratio [aOR] 1.17, 95% CI 0.83-1.65). Broad-spectrum antibiotics were administered to 47.9% of tested and 42.4% of untested patients (aOR 1.25, 95% CI 1.00-1.55) at discharge. Overall, there were 212 pneumococcal cases, with 30/212 (14%) solely detected by UAT. Of patients with positive pneumococcal UAT, 26% received broad-spectrum antibiotics at discharge, compared with 46% of UAT-negative patients (aOR 0.41, 95% CI 0.18-0.96). Mortality was similar in tested and untested patients. Tested patients received more broad-spectrum antibiotic treatment than untested patients, while patients with positive pneumococcal UAT received more narrow-spectrum antibiotics. Of all pneumococcal cases, 14% were diagnosed exclusively by UAT, suggesting usefulness in antimicrobial stewardship.