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Capsular types and antimicrobial resistance of Streptococcus pneumoniae isolated in Korea
1Department of Clinical Pathology, Yonsei University College of Medicine, Seoul, Korea.
Abstract:
The capsular types and the MICs of penicillin G and other antimicrobial agents were determined for 89 isolates of Streptococcus pneumoniae. MICs of penicillin G ranged from 0.015 to 2 mg/l, with 29% and 48% of the isolates exhibiting intermediate resistance and complete resistance, respectively. All isolates were susceptible to teicoplanin and vancomycin, but 81% and 43% of the penicillin G-resistant strains were intermediately resistant to cefotaxime and imipenem, respectively. Strains belonged to 16 different capsular types: 73% belonged to types 19F and 23F, and 97% of strains belonging to these two types exhibited either intermediate or complete resistance to penicillin G.
Insights
Penicillin resistance is high in Streptococcus pneumoniae, especially in common capsular types 19F and 23F. Most strains remained susceptible to vancomycin and teicoplanin.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Streptococcus pneumoniae is a leading cause of bacterial infections worldwide.
- Penicillin G resistance in S. pneumoniae is a growing public health concern.
- Understanding the prevalence of specific capsular types and their resistance patterns is crucial for effective treatment strategies.
Purpose of the Study:
- To determine the capsular types of Streptococcus pneumoniae isolates.
- To assess the minimum inhibitory concentrations (MICs) of penicillin G and other antimicrobial agents.
- To investigate the correlation between capsular type and antimicrobial resistance.
Main Methods:
- Analysis of 89 Streptococcus pneumoniae isolates.
- Determination of capsular serotypes.
- Antimicrobial susceptibility testing using MICs for penicillin G, cefotaxime, imipenem, teicoplanin, and vancomycin.
Main Results:
- 48% of isolates showed complete resistance to penicillin G, and 29% showed intermediate resistance.
- Capsular types 19F and 23F were most prevalent (73% of isolates).
- 97% of strains with types 19F and 23F exhibited intermediate or complete penicillin G resistance.
- All isolates were susceptible to teicoplanin and vancomycin.
- Penicillin G-resistant strains showed high rates of intermediate resistance to cefotaxime (81%) and imipenem (43%).
Conclusions:
- High rates of penicillin G resistance are present in Streptococcus pneumoniae, particularly in prevalent capsular types 19F and 23F.
- Vancomycin and teicoplanin remain effective against all tested S. pneumoniae isolates.
- Emerging resistance to other beta-lactams like cefotaxime and imipenem in resistant strains warrants close monitoring.