Shormin M1, Khandaker M2, Ferdouse F3
Abstract : Background: Nasopharyngeal carriage of Streptococcus pneumoniae is thought to be a risk for invasive pneu mococcal diseases. Detection and monitoring of pneumococcal carriage and distribution of serotype is important to assess the impact and effectiveness of pneumococcal vaccine programs. Diversity among the serotypes and changes in the prevalence of serotypes over time are challenges in designing the ultimate pneumococcal vaccines. Objectives: To determine the predominant serotypes and to establish the trend of serotype changes so that the vaccination against predominant serotypes can be evaluated after its introduction. Materials and Methods: The study was conducted in the department of microbiology of Dhaka Medical College Hospital (DMCH).200 nasopharyngeal swabs were collected from healthy children aged one month to less than five years who attended the outpatient department of DMCH for routine immunization, child growth monitoring and nutritional advice.S. pneumoniae were isolated and identified by culture, Gram staining and biochemical test and PCR. Result: Out of 200 nasopharyngeal swabs, 92 (46%) were positive by PCR. Out of 200 children, 90 (45%) were received pneu mococcal conjugate vaccine (PCV) and 110 (55%) were not vaccinated. Among vaccinated children, 4 (16%) S. pneumoniae were detected in fully vaccinated children and 25 (38.46%) S. pneumoniae were detected in partially vaccinated children by PCR. Among not vaccinated children, 63 (57.27%) S. pneumoniae were detected by PCR. The difference between fully vaccinated and non-vaccinated proportion is statistically significant (p<0.001) and the difference between fully vaccinated and partially vaccinated proportion is statistically significant (p< 0.001).Out of 4 fully vaccinated PCR positive cases, detected serotypes were 34F (1) and 35B (1) and 6B (1) among 3 children. Out of 25 PCR positive partially vaccinated children, detected serotypes were 34F (7), 35B (3), 6B (3), 14(3), 23(2) among 18 children. Out of 63 PCR positive not-vaccinated children, detected serotypes were 3 (3), 4 (1), 6A (11), 6B (7), 7F (1), 14 (4), 18C (1), 19A (2), 19F (2), 23F (3), 34F (8), 35B (8) among 51 children. Conclusion: This study showed detection of serotypes of S. pneumoniae from nasopharyngeal swabs in children may help to predict the shift in serotypes replacement following pneumococcal conjugate vaccination. Keywords: Streptococcus pneumoniae (SPN), Invasive pneumococcal diseases (IPD), Pneumococcal conju gate vaccine, Vaccine type (VT), Non-vaccine type (NVT)
