Clinical Performance of BALF Droplet Digital PCR for Differential Diagnosis of Pneumocystis jirovecii Pneumonia and Pneumocystis jirovecii Colonization

Abstract

BackgroundAccurate differentiation between Pneumocystis jirovecii (Pj) infection and colonization is crucial for effective treatment. MethodsFrom September 2016 to June 2022, 89 immunocompromised patients with unexplained lung infiltrates and clinical suspicion of Pj pneumonia were enrolled at Peking University People's Hospital. Bronchoalveolar lavage fluid (BALF) of these patients were detected by quantitative PCR (qPCR) and droplet digital PCR (ddPCR). ResultsThe performance of ddPCR was superior to qPCR in detecting Pj infection. Area under the curve was 0.97 (95%CI: 0.94–1) for ddPCR of the BALF in all patients. The optimal threshold value for discriminating Pj infection from colonization was 13.98 copies/test, with a sensitivity of 97.96%, specificity of 85.71%. No obvious correlation between ddPCR copy number and disease severity was observed. ConclusionBALF ddPCR exhibits robust potential in detecting Pj and effectively discriminating colonization and infection.