Rapid molecular detection of respiratory pathogens in patients admitted with suspected community-acquired pneumonia: secondary analysis of a randomized controlled trial

In a randomized trial, we demonstrated that implementing point-of-care (POC) PCR detection of respiratory pathogens in an emergency department (ED) setting did not change overall antibiotic use but led to more targeted treatment and a clinically relevant, albeit non-significant, reduction in length of stay. This study aimed to assess the diagnostic impact of POC-PCR testing in patients with suspected community-acquired pneumonia (CAP) in the ED. This study is a secondary analysis of a Danish multicenter randomized controlled trial (RCT) that included patients aged ≥18 years admitted to the ED between March 2021 and February 2022. In the primary trial, patients were randomly assigned to one of two parallel groups: (i) intervention group: POC-PCR in addition to standard care, or (ii) control group: standard care only (SCO). The present secondary analysis focuses exclusively on patients in the intervention group, where both POC-PCR and standard culture-based diagnostics were performed. The diagnosis of CAP was determined by an expert panel. In the intervention group, 145 patients had a lower respiratory tract (LRT) specimens analyzed using both POC-PCR and culture. POC-PCR identified notably more microorganisms compared with culture (187 vs 34). The agreement between positive results obtained by POC-PCR and culture was 6 of 19 (31.6%) for Streptococcus pneumoniae and 16 of 61 (26%) for Haemophilus influenzae. Concentrations of ≥10⁷ copies/mL detected by POC-PCR for S. pneumoniae and H. influenzae were associated with a diagnosis of CAP. Of the 67 patients identified with S. pneumoniae and/or H. influenzae, 46 (69%) received targeted treatment, 57 (85%) received adequate treatment, and 10 (15%) received inappropriate treatment. The rapid pathogen detection by POC-PCR is likely to improve diagnostic accuracy and promote appropriate use of antibiotics in CAP patients.