Serotype distribution of Streptococcus pneumoniae strains in the nasopharynx of healthy Turkish children

Abstract

Background & objective: There is scanty information available on the pharyngeal carriage of Streptococcus pneumoniae and serotype distribution in healthy Turkish children. We therefore undertook this study to determine the serotype prevalence of pharyngeal S. pneumoniae isolates of healthy school children in Turkey.

Methods: Pharyngeal swabs were collected from 1440 healthy children (Ages 6-13) between April 2003 and March 2004. S. pneumoniae was identified by standard microbiological culture methods. The serotyping was performed and penicillin minimal inhibitory concentration was detected by the E test.

Results: S. pneumoniae carrier rate was 13.9 per cent (n=201) and penicillin resistance 12.9 per cent (n=26). Twenty four of 201 (11.9%) isolates were found intermediately resistant and 2 of 201 (1%) highly resistant by E test. A total of 169 of 201 (84%) pneumococcal isolates were typable with the available antisera. The six most frequent serotypes were 6, 19, 1, 23, 20 and 17. The majority of penicillin-resistant isolates were serotypes 20, 23, 14, 6 and 19.

Interpretation & conclusion: The serotype distribution of the isolates showed diversity and that some common circulating serotypes are invasive. A majority of invasive serotypes are covered by pneumococcal conjugate vaccine formulations in at risk groups of children suggesting that vaccine use could reduce the incidence of invasive pneumococcal disease.