The incidence of invasive pneumococcal disease (IPD) has decreased after pneumococcal conjugate vaccine used; however, a breakthrough infection may still be seen after vaccination. In this study, eight pediatric inpatients and nine episodes with IPD in our center were included. Their age and gender, diagnoses, facilitating factors, the status of immunization and the antibiotic resistance of Pneumococci, serotypes of Pneumococci were noted. The isolates were subjected to disc susceptibility tests for penicillin, macrolides, and fluoroquinolones, according to the guidelines of the Clinical and Laboratory Standards Institute. Of the vaccinated seven cases, four of them (57.1%) developed IPD which their serogroups were in vaccine content. It was observed that all four cases in question had an underlying facilitating factor. Pneumococcal antibiotic susceptibility is also crucial. Three of nine isolates (33.4%) were resistant, and one isolate (11.2%) was intermediate susceptible to penicillin. Six of the nine isolates (66.7%) had macrolide resistance in our investigation. Invasive pneumococcal infections with serogroups that exist in pneumococcal conjugate vaccine content may occur in vaccinated individuals.