Distribution of capsular types and drug resistance patterns of invasive pediatric Streptococcus pneumoniae isolates in Teheran, Iran

- This is the most comprehensive study on serotype distribution and drug resistance patterns of invasive pediatric pneumococcal isolates in Iran.
- Since no suitable vaccine is recommended for this area, the results of this study will help to design an appropriate vaccination program in Iran.
- The capsular types of invasive pediatric pneumococci by were determined by modified sequential multiplex PCR.
- The BACTEC system was used for primary isolation. Thus, it is expected that missed pneumococcal isolates will have been minimized.

SummaryObjectivesTo explore the serotype distribution and drug resistance patterns of invasive pneumococcal isolates from children under 5 years of age.MethodsDuring a 32-month period, 585 clinical samples (including blood, cerebrospinal fluid (CSF), and synovial fluid) from children suspected of having meningitis, sepsis, pneumonia, or septic arthritis were analyzed using the BACTEC culture system. Positive cultures were examined using biochemical tests and lytA amplification for the identification of pneumococcal strains. The confirmed pneumococcal isolates were examined to determine capsular types using a modified sequential multiplex PCR and susceptibility to antimicrobial agents.ResultsFifty-three pneumococcal isolates were detected in the 585 clinical samples: 21 (39.6%) blood samples and 32 (60.4%) CSF samples. The most frequent serotype was 23F (24.5%), followed by serotypes 19F (18.9%), 19A (7.5%), and 9V (7.5%). Twenty-one percent of pneumococcal isolates were penicillin-non-susceptible and serotype 19A was significantly associated with resistance to penicillin.ConclusionsThis study indicated that the 13-valent pneumococcal conjugate vaccine (PCV13) could cover the majority of the invasive pneumococcal isolates. Drug-resistant and multidrug-resistant Streptococcus pneumoniae strains are circulating in Iran. Therefore, public immunization of infants using PCV13 is recommended to reduce the incidence of pneumococcal disease and pneumococcal-resistant strains in Teheran.