Streptococcus pneumoniae is the most common causative agent of pneumonia in children. Despite the worldwide use of the 7-valent pneumococcal conjugate vaccine, the frequency of necrotizing pneumococcal pneumonia (PNP) is increasing. Currently, there is a general increase in the frequency of infections caused by pneumococcal serotypes not included in the vaccine.

The aim of a study conducted in Utah (USA) was to describe the temporal trends in the occurrence of PNA and to assess the role of various pneumococcal serotypes in the occurrence of this disease. In a retrospective analysis of data from all children under the age of 18 who received treatment in a hospital for pneumonia confirmed by radiography from January 1997 to March 2006 and who had blood, sputum and bronchial contents obtained during a bronchoalveolar lavage or pleural puncture was seeded S. pneumoniae, and genotyping of all isolated strains of pneumococcus was performed.

A total of 124 children with pneumococcal pneumonia were identified during the period indicated; 33 patients (27%) had X-ray confirmation of the PUP. During the period 1997 to 2000, 5 (13%) of the 39 cases of confirmed cultural pneumococcal pneumonia were considered to be PNP. Between 2001 and 2006, 28 of the 85 cases of pneumococcal pneumonia (33%) were complicated by PNA. Serotypes not contained in the 7-valent pneumococcal conjugate vaccine represented 49% of all strains isolated for the period 1997-2000. and 88% for the period 2001-2006. Most often, the occurrence of PNA was noted in the case of isolation of the pneumococcal serotype 3 - thus, 11 cases out of 14 of PNP (79%) were caused by this serotype S. pneumoniae . When compared with all other serotypes, it turned out that serotype 3 was statistically significantly more likely to cause necrosis (odds ratio 14.67, 95% confidence interval 3.39-86.25).

Thus, pneumococcal necrotizing pneumonia is a serious complication, the incidence of which in pneumonia caused by S. pneumoniae, has recently increased. If the causative agent of pneumonia is S. pneumoniae 3, the risk of necrotizing pneumonia increases significantly. In conclusion, the authors note that when developing vaccination strategies, the change in epidemiology of invasive pneumococcal infections should be considered.