Streptococcus pneumoniae re-emerges as a cause of community-acquired pneumonia, including frequent co-infection with SARS-CoV-2, in Germany, 2021

ABSTRACT

BackgroundThe COVID-19 pandemic and the associated containment measures had a substantial impact on pathogens causing pneumonia in adults. The objective of this study was to determine the etiology of hospitalized community-acquired pneumonia (CAP) among adults in Germany in 2021, the second year of the COVID-19 pandemic. MethodsSince January 2021, this on-going, prospective, population-based surveillances study enrolled adult patients with clinically and radiographically confirmed CAP at three hospitals in Thuringia, Germany, serving a population of approximately 280,000. Urine samples were collected from patients and tested for S. pneumoniae using the pneumococcal urinary antigen test (PUAT, BinaxNOW S. pneumoniae) and the proprietary serotype-specific urinary antigen detection (UAD) assays. Nasopharyngeal swabs were tested for 10 respiratory viruses by PCR. ResultsA total of 797 patients were enrolled, of whom 760 were included in the analysis. The median age of patients with CAP was 67 years; in-hospital case-fatality rate was 8.4%. A respiratory pathogen was detected in 553 (72.8%) patients. The most common pathogen was SARS-CoV-2 (n=498, 68.2%), followed by S. pneumoniae (n=40, 6.4%). Serotypes contained in the 13-valent, 15-valent and 20-valent pneumococcal conjugate vaccine were detected in 42.5%, 45.0%, and 70.0% of the pneumococcal CAP cases. Between the first and second half of 2021, the proportion of CAP cases associated with S. pneumoniae increased from 1.1% to 5.6% in patients aged 18-59 years and from 2.5% to 12.4% in those aged [≥]60 years; coinfection of SARS-CoV-2 and S. pneumoniae among COVID-19 patients increased from 0.7% (2/283 cases) to 6.0% (13/215) in patients aged [≥]18 years, and from 1.0% (2/195) to 8.7% (11/127) in those aged [≥]60 years. ConclusionIn Germany, the proportion of CAP cases associated with S. pneumoniae rebounded to a near-pandemic level in the second half of 2021 and many pneumococcal infections occurred in patients with COVID-19. Vaccination uptake against respiratory pathogens, including S. pneumoniae, should be strengthened.