Colonization rates and immune status of children against Streptococcus pneumoniae before the introduction of pneumococcal conjugate vaccine

Abstract

Pneumococcal infections contribute to high morbidity and mortality in Pakistan. Pneumococcal colonization rates and immune status of children before and after vaccination can serve as an important indicator to determine the success of immunization program. Aim of this study was to determine the pneumococcal colonization rate and immune status of children (<3-years) before the introduction of Pneumococcal immunization in EPI program. A cross sectional study of 3-months duration was conducted in collaboration with EPI Centre of NICH, Karachi. A total of 192 healthy children aged 3-months to 3-years were included in the study. Children with chronic or recurrent pulmonary disease were excluded. Demographic data and presence of any risks for pneumococcal colonization or immunity was recorded. Nasopharyngeal swabs were collected to determine the presence of S. pneumoniae and sensitivity pattern of the isolates. Blood samples were collected to determine immune status of these children. Sixty (31%) children were found to carry S. pneumoniae in their nasopharynx. Resistance to cotrimoxazole, erythromycin, chloramphenicol, penicillin and vancomycin was 100%, 30%, 25%, 22% and 0% respectively. Mean anti-PCP titre of children was 23.3mg/L. Mean antiPCP titre in children who had previously suffered from RTI was significantly increased (p-value 0.039). This study may serve as baseline report for evaluating the success of pneumococcal immunization in future. A significant drop in nasopharyngeal colonization rates post vaccination would depict the success of pneumococcal immunization.