[Invasive pneumococcal disease in two non-vaccinated pediatric cases: pleural empyema and bacteremia]

Streptococcus pneumoniae, a gram-positive diplococcus, is the causative agent of invasive pneumococcal diseases (IPDs) characterized by severe infections such as bacteraemia, sepsis and meningitis. S.pneumoniae and IPDs are situated in the focus of the vaccine studies because of being encompassed of a significant burden of disease in the world, severe mortality and morbidities, and location in vaccine-preventable diseases group. Although S.pneumoniae has more than 90 defined serotypes, certain serotypes are often identified as the cause of IPDs. Individuals with comorbid and chronic diseases, primary or secondary immune deficiencies, and <2 years or >65 years of age are at increased risk for IPDs. Currently, a 23-valent polysaccharide vaccine and also 7, 10 and 13 valent pneumococcal conjugated vaccines (PCV) have been produced for pneumococci. Phase studies of protein based vaccines, which will provide protection independent of serotypes, and 15-valent pneumococcal conjugated vaccine are still ongoing. In Turkey, in November 2008 PCV7 and in April 2011 PCV13 have been implemented in the national immunization program. First case of the pneumococcal unvaccinated cases presented in this report was a 6-year-old girl patient with pneumonia and pleural empyema due to S.pneumoniae serotype 1, without any underlying risk factors. The other case is a 52-days-old male patient, who had a history of pneumococcal septicemia in the newborn period and was followed for bacteremia associated S.pneumoniae serotype 12B and diagnosed as complement deficiency on follow-up. S.pneumoniae serotype 1 is within serotypes covered by 10 and 13 valent pneumococcal conjugate vaccines and pneumococcal polysaccharide vaccine that are in use today, and is a highly invasive strain often isolated in pneumococcal lobar pneumonia and empyema. S.pneumoniae serotype 12B is a non-vaccine serotype not included in any of conjugate and polysaccharide vaccines, and usually obtained in respiratory infections and nasopharyngeal carriage studies. The first case of this report was presented because of an IPD with a serotype included in PCV13 implemented in the routine childhood vaccination schedule and to give an idea about pneumococcal strains circulating in the community. The second case was discussed to draw attention for the evaluation of immune deficiencies and other risk factors in recurrent infections with encapsulated bacteria such as pneumococci. Pneumococcal conjugate vaccines contribute the public immunity with the reduction of vaccine-type pneumococcal nasopharyngeal carriage, IPD incidence, and IPD associated morbidity and mortality especially in young children, at the same time cause a decrease in the prevalence of antibiotic-resistant infections. Application of the pneumococcal conjugate vaccines covering the whole society is important, according to all these important results.