Molecular Characterization of Streptococcus Pneumoniae from Patients Diagnosed with Pneumonia: Recommendation for Vaccination Program

Background: Infections caused by Streptococcus pneumoniae (S. pneumoniae) have remained a significant public health concern worldwide. In developed countries, the highest prevalence of S. pneumonia has been reported among the elderly. The aim of this study was to evaluate the coverage of genotypes in the 13-valent pneumococcal conjugate vaccine (PCV-13) in the Iranian elderly population. Methods: A total of 41 isolates of S. pneumoniae were collected in the current retrospective cross-sectional study. The samples comprised 33 inpatients hospitalized for pneumococcal pneumonia and 8 outpatients. Multiplex polymerase chain reaction assay was performed to categorize the bacteria isolated into specific genotypes. Statistical analyses were performed using SPSS software, and the chi-square test was used to assess the statistical significance in percentages. Results: A total of 68 genotypes were identified in this study, in which 39 isolates (57.3%) were associated with invasive infections. The most common genotypes were 6A/B [8 (19.5%)], 1 [7 (17.5%)], 14 [5 (12.2%)], and 19A [4 (9.75%)], respectively. The coverage rates of PCV-7, PCV-10, and PCV-13 vaccines were 51.17%, 70.7%, and 99.9%, respectively. According to our results, the pneumococcal coverage rate of PCV-7, PCV-10, and PCV-13 vaccine types is estimated to be 51.2%, 70.7%, and 99.9%, respectively. Furthermore, the trend of pneumococcal serotypes included in the PCV-13 was steadily increasing during the study period. Conclusion: It can be concluded that the most circulating pneumococcal serotypes were in accordance with specific serotypes included in the PCV-13 vaccine types. Therefore, including PCV-13 vaccines in immunization programs against pneumococcus in the elderly can effectively reduce the rate of infections.