Analysis of serotype prevalence in recently isolated non-invasive S. pneumoniae strains

Jung Sang-Oun, Yoo Hye-Sun, Yoo Jae-Il, Hwang Kyu Jam
Division of Bacterial Diseases, Center for Laboratory Control of Infectious Diseases, KCDC

The recent serotype prevalence of Streptococcus pneumonia, isolated from the non-invasive pneumococcal diseases was analyzed. A total of 225 S. pneumoniae strains were isolated from non-invasive specimens for 8 months from October 2017 to May 2018. The regional distribution of the collected strains revealed a high frequency in Gyeonggi (27.1%) and Gyeongsang (26.7%) provinces. Most (94.2%) of the strains were isolated from sputum. Most of the strains were isolated from adults ≥65 years of age (58.2%) and 19-64 years of age (38.2%). Serotype analysis revealed the highest prevalence of 19A (13.3%), followed by 11A (10.7%), 19F (9.3%), and 23A (9.3%), with a low prevalence of serotypes 8, 9N, 17A and 14 (all 0.4%). Serotypes 19A and 19F were prevalent in all three age groups. Fifteen vaccine serotypes were confirmed from the total of 24 vaccine serotypes (PCV13 and PPSV23). The most prevalent types was 19A (23.4%), followed by 11A (18.8%), 19F (16.4%), and 3 (15.6%). Eleven non-vaccine serotypes were also confirmed with higher prevalence of 23A (21.6%), 35B (18.6%), and 34 (18.6%). Compared to the previous report, a periodic serotype distribution in non-invasive S. pneumoniae strains with a similar pattern may be evident. Further comparison with the results of serotype analysis of invasive strains is needed.

Keywords: Streptococcus pneumoniae, serotype, prevalence, vaccine, non-invasive