Streptococcus pneumoniae is the main etiologic agent of community-acquired invasive infections, especially in extreme age groups. Recently, the emergence of pneumococcal conjugate vaccines (PCV) brought a possibility to reduce the number of pneumococcal infections. Their introduction requires a knowledge concerning epidemiology of infections, which in different part of the world differs and changes with time, and therefore must be under permanent surveillance.
The aim of this study: To characterize invasive pneumococcal disease (IPD) in Poland in 2010 based on data collected by the National Reference Centre for Bacterial Meningitis (NRCBM).
Material and methods: The study was performed on all invasive S. pneumoniae isolates collected in 2010 by the NRCBM. All the strains were identified and serotyped based on routine techniques. Minimal inhibitory concentrations (MICs) were determined by the Etest or M.I.C. Evaluators method. For the incidence rate assessment, cases where the pneumolysin gene was detected by PCR in clinical material were included.
Results: The highest IPD incidence rates were among children under 5 years of age (3.43/100,000), and especially among children under 2 years of age (5.17/100,000). The vaccines PCV10 and PCV13 covered 54.9, and 75.4% of all IPD cases, 71.0 and 93.5% of cases among children under 2 years of age, and 71.2 and 92.3% among children under 5 years of age, respectively. Decreased susceptibility to penicillin (MIC > 0.06 mg/l) and cefotaxime (MIC > 0.5 mg/l) was found in 30.7 and 14.8% of isolates, respectively. All isolates were susceptible to rifampicin and vancomycin. Intermediate susceptibility and resistance to meropenem was notified in 6.1 and 5.7% of isolates. Resistance to chloramphenicol, erythromycin, clindamycin, tetracycline and co-trimoxazole was found in 8.0, 36.7, 29.9, 30.7 and 34.5% of isolates, respectively.
Conclusions: Results of the study showed high theoretical coverage of pneumococcal conjugate vaccines among IPD cases in general and especially among infections caused by isolates with decreased susceptibility to antibiotics. Therefore, it seams that the best way to limit invasive pneumococcal disease-associated morbidity and mortality, especially of cases caused by bacteria with decreased susceptibility to antibiotics, is the inclusion of a PCV in the immunization programme in Poland.