The serotype-specific prevalence of pneumococci in hospitalized pneumonia patients with COPD: a prospective, multi-center, cohort study

Abstract

Background/Aims: The overall incidence of pneumococcal pneumonia is declining. However, the change in the pathogenic distribution of community-acquired pneumonia (CAP) in chronic obstructive pulmonary disease (COPD) patients and the serotype specificity of <i>Streptococcus pneumoniae</i> have not been evaluated in the post-era of pneumococcal vaccination in Korea.Methods: We conducted a prospective, multi-center, cohort study from seven University-affiliated hospitals. The primary objective was the identification of serotype-specific prevalence of pneumococcal pneumonia in COPD patients hospitalized for CAP. For the purpose, we conducted serotype-specific urine antigen detection (SS-UAD) assays for <i>S. pneumoniae</i>. The secondary objectives were other clinical characteristics of pneumonia including vaccination status.Results: The total number of participants was 349. Most of them were male (95.1%) with old ages (75.55 ± 8.59 y). The positive rate for <i>S. pneumoniae</i> was 9.2% with SS-UAD assay and the common serotypes were 22F, 6A, and 6B. In the sputum, <i>Pseudomonas aeruginosa</i> (5.0%) and <i>Haemophilus influenzae</i> (4.0%) were common pathogens. The vaccination rate was 78.8%, 53.0%, and 25.8% for influenza, pneumococcal polysaccharide vaccine 23 (PPV 23), and pneumococcal protein- conjugated vaccine 13 (PCV 13), respectively. Thirteen patients died during hospitalization (mortality rate; 3.7%). There was no difference in the respective rate of influenza vaccination (79.2% vs. 69.2%, <i>p</i> = 0.288) and PCV 13 vaccination (25.6% vs. 30.8%, <i>p</i> = 0.443) between survivors and the deceased.Conclusions: Serotypes 22F, 6A, and 6B, which are covered either by PPV 23 or by PCV 13, are still common pneumococcal serotypes in COPD pneumonia in the post-vaccination era in Korea.