Prospective, population-based surveillance of the burden of Streptococcus pneumoniae in community-acquired pneumonia in older adults, Chrzanów County, Poland, 2010 to 2012.

Introduction: Community-acquired pneumonia (CAP) caused by Streptococcus pneumoniae is a substantial cause of morbidity and mortality among older adults. This study estimated incidences of CAP, chest x-ray-confirmed CAP (CXR+CAP), S pneumonia- positive CAP, S pneumonia-positive CXR+CAP, and S. pneumoniae serotype distribution among 46,000 at-risk adults aged ≥ 50 years residing in Chrzanów County, Poland.

Material and methods: From January 2010 to January 2012, all facilities providing ambulatory and inpatient care enrolled all consenting resident patients with suspicion of CAP. Chest x-rays, urine, blood, and sputum samples were analyzed. Annualized incidence rates were determined. Presence of S pneumonia-positive CAP and/or S. pneumoniae serotype distribution was determined using the urine antigen detection assay (capable of detecting the serotypes in the 13-valent pneumococcal conjugate vaccine [PCV13]), BinaxNOW®, and/or microbiology cultures.

Results: Among 5055 enrolled patients, 1195 (23.7%) were diagnosed with CAP and 1166 (23.4%) had CXR+CAP. S. pneumoniae was detected in 144 (12.1%) and 131 (11.2%) patients from the CAP and CXR+CAP cohorts, respectively. Annualized incidence rates of CAP, CXR+CAP, S pneumonia-positive CAP, and S. pneumonia-positive CXR+CAP were 12.8, 12.5, 1.6, and 1.4 per 1000 residents, respectively. Among CXR+CAP patients, 39.7% were aged 50 to 64 years and 60.3% were aged ≥ 65 years. Incidence rates generally increased with age. The most common serotypes in S. pneumoniae-positive CXR+CAP patients were 3 (n = 15), 23F (n = 10), 18C (n = 9), and 9V (n = 6).

Conclusions: CAP due to PCV13 serotypes is a source of morbidity among adults >50 years and may be reduced by greater access to pneumococcal vaccines.