Medicinski Podmladak (Jan 2020)
Characterization of Streptococcus pneumoniae strains isolated from patients with meningitis before the introduction of pneumococcal conjugate vaccine in Serbia
Abstract
Introduction: Pneumococcal meningitis is a serious disease which affects mostly children ≤ 2 years, adults ≥ 65 years and immunodeficient patients. The introduction of pneumococcal conjugate vaccine (PCV) into immunization programs worldwide has led to a significant decrease in the incidence of invasive pneumococcal disease, reduction of antibiotic resistance and changes in the distribution of pneumococcal serotypes. In 2018, PCV10 was introduced into the National Immunization Program in Serbia. Aim: The aim of this study was to analyze the serotype distribution and antibiotic susceptibility of pneumococcal strains isolated from meningitis cases in the pre-vaccinal period (2009-2018) in Serbia. Material and methods: Meningeal isolates were sent into the National Reference Laboratory for streptococci between January 2009 and December 2018 for serotyping and antimicrobial susceptibility testing (AST). Serotyping was performed by Quellung reaction, while AST was performed using disk diffusion method and E-test. Results: A total of 199 strains were analyzed and 32 different serotypes have been identified. Among the 55 (27.64%) strains from children ≤16 years, 17 different serotypes were detected of which 19F, 14, 6A, and 6B were the most common. Regarding the 144 (72.36%) adult isolates, 30 different serotypes were present, the most common being 3, 19F, 14, 23F, 6A and 6B. The coverage of pediatric serotypes was 61.82% for PCV10 and 78.18% for PCV13. Statistically significant number of isolates showed resistance to: penicillin (53.26%), erythromycin (45.73%), clindamycin (40.20%), trimethoprim-sulfamethoxazole (34.17%) and tetracycline (34.17%). The isolates from children were more resistant to beta-lactams and macrolides (p < 0.05). Conclusion: During the pre-vaccinal period in Serbia, vaccinal serotypes dominated over non-vaccinal serotypes. Resistance is intermediate to high in the dominant serotypes of children and low in the most common adult serotype 3. Taking into consideration the possible changes in the pneumococcal population in the future, continued monitoring of post-vaccine serotype and resistance trends are essential.
