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Distribution of serotypes and antibiotic resistance among pneumococci in Northern Ireland
A C Lafong1, E Crothers, K B Bamford
1Bacteriology Laboratory, Belfast City Hospital, U.K.
Abstract:
Altogether, 488 consecutive strains of Streptococcus pneumoniae isolated from clinical specimens were serotyped and their antibiotic susceptibility determined. Of all strains isolated, 89.7% (90.6% for strains isolated from patients with serious infection) were of types present in the new polyvalent (23-valent) pneumococcal vaccine. Four strains showed reduced susceptibility to penicillin (minimum inhibitory concentration 0.1-1.0 mg/l). Two of those strains (both serotype 23) were also of intermediate susceptibility to other antibiotics (ampicillin, cephradine, chloramphenicol and tetracycline) but were sensitive to erythromycin. A significant proportion (12%) was resistant to tetracycline.
Insights
Most Streptococcus pneumoniae clinical isolates are covered by the 23-valent pneumococcal vaccine. However, some strains show reduced antibiotic susceptibility, particularly to tetracycline.
Area of Science:
- Clinical microbiology
- Infectious diseases
- Vaccinology
Background:
- Streptococcus pneumoniae is a leading cause of bacterial infections worldwide.
- Pneumococcal vaccines are crucial for preventing invasive pneumococcal disease.
- Monitoring serotypes and antibiotic resistance is essential for public health.
Purpose of the Study:
- To serotype clinical isolates of Streptococcus pneumoniae.
- To determine the antibiotic susceptibility patterns of these isolates.
- To assess the coverage of the 23-valent pneumococcal vaccine against circulating strains.
Main Methods:
- Serotyping of 488 clinical isolates of Streptococcus pneumoniae.
- Antibiotic susceptibility testing using standard microbiological methods.
- Analysis of serotype distribution and resistance profiles.
Main Results:
- 89.7% of isolates belonged to serotypes included in the 23-valent pneumococcal vaccine.
- 12% of strains exhibited resistance to tetracycline.
- Four strains showed reduced susceptibility to penicillin; two of these (serotype 23) had intermediate resistance to other antibiotics but remained sensitive to erythromycin.
Conclusions:
- The 23-valent pneumococcal vaccine likely covers a high proportion of currently circulating Streptococcus pneumoniae strains.
- Emerging antibiotic resistance, particularly to tetracycline and penicillin, is a concern.
- Continued surveillance of serotypes and antimicrobial resistance is critical for effective pneumococcal disease prevention and treatment.