Introduction: Invasive pneumococcal disease (IPD) incidence, serotype distribution, and antibiotic susceptibility of Streptococcus pneumoniae were estimated in children aged 28 days to < 60 months.
Material and methods: One-year prospective, hospital-based surveillance was conducted starting on February 15, 2008, at two children’s hospitals serving the city and surrounding county of Poznań and Poznański, Poland. Eligible children had fever  39.0°C or physician-suspected IPD. Blood cultures were obtained from all children, cerebrospinal fluid in suspected meningitis cases, and chest radiographs (CXRs) in suspected pneumonia cases.
Results: Seven of 1,581 eligible children had confirmed IPD. Estimated IPD incidence per 100,000 children was 11.89 (95% CI: 4.78–24.50) overall and 20.1 (95% CI: 6.52–46.84) in subjects aged 28 days to < 24 months. One S. pneumoniae isolate of each of the following serotypes was obtained: 6B, 14, 23A, 23F, and 33F. Two isolates were resistant to both trimethoprim-sulfamethoxazole and erythromycin. Clinical pneumonia incidence among children aged 28 days to < 24 months and 24 months to < 60 months was 3,151.3 (95% CI: 2934.7–3379.7) and 962.7 (95% CI: 861.2–10,072.9) per 100,000 children, respectively. CXR-confirmed pneumonia rates in the same groups were 1,035.7 (95% CI: 913.2–1,170.1) and 379.8 (95% CI: 317.1–451.3) per 100,000 children, respectively.
Conclusions: IPD is an important cause of morbidity in Poznań and Poznański county, Poland. Among participants aged < 5 years with fever or suspected IPD, pneumonia was the most common diagnosis and was highest in children aged < 24 months.