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Invasive Streptococcus pneumoniae infections: serotype distribution and antimicrobial resistance in Canada, 1992-1995
M Lovgren1, J S Spika, J A Talbot
1National Centre for Streptococcus, Provincial Laboratory of Public Health, Northern Alberta, Edmonton. ml@bugs.uah.ualberta.ca
Objective:
To report current information about invasive pneumococcal infections, capsular types and antimicrobial resistance in Canada.
Design:
Retrospective analysis.
Setting:
Canada.
Patients:
A total of 976 patients from whom Streptococcus pneumoniae was isolated from blood or cerebrospinal fluid between Jan. 1, 1992, and Dec. 31, 1995.
Outcome Measures:
Capsular type and antimicrobial susceptibility.
Results:
Twenty types accounted for 90.8% of the isolates from patients over 5 years of age; all but type 15A are covered by the currently available 23-valent vaccine. Nine types accounted for 92% of the isolates recovered from children 5 years and less. Reduced susceptibility to penicillin was found in 7.8% of the collection and was associated with types 6B, 9V and 19A. Full resistance to penicillin was observed most frequently during 1995 and was associated with type 9V. Rates of reduced susceptibility over one 12-month period were 19.5% for trimethoprim-sulfamethoxazole and 4.5% or less for each of cefotaxime, ceftriaxone, chloramphenicol, erythromycin, ofloxacin and tetracycline.
Conclusions:
Over 90% of invasive pneumococcal infections are covered by the currently available vaccines (for people over 2 years of age) and the pneumococcal protein-polysaccharide conjugate vaccines under development for young children. The high frequency of antimicrobial resistance observed requires more complete investigation and confirmation; however, taken from a global perspective, it supports the need to develop better control strategies, including greater use of new and existing vaccines.
Insights
Invasive pneumococcal infections in Canada show high vaccine coverage for most types, but rising antimicrobial resistance, especially to penicillin, necessitates updated control strategies and vaccine development.
Area of Science:
- Microbiology
- Infectious Diseases
- Vaccinology
Background:
- Invasive pneumococcal infections remain a significant public health concern globally.
- Streptococcus pneumoniae (pneumococcus) is a leading cause of bacterial pneumonia, meningitis, and sepsis.
- Antimicrobial resistance in pneumococcal isolates poses a growing challenge to effective treatment.
Purpose of the Study:
- To provide current data on invasive pneumococcal infections in Canada.
- To identify prevalent pneumococcal capsular types.
- To assess antimicrobial resistance patterns in Streptococcus pneumoniae isolates.
Main Methods:
- Retrospective analysis of 976 patient isolates of Streptococcus pneumoniae.
- Isolates were obtained from blood or cerebrospinal fluid between January 1992 and December 1995.
- Analysis included capsular typing and antimicrobial susceptibility testing.
Main Results:
- Twenty capsular types covered 90.8% of isolates in patients over 5 years old; 23-valent vaccine covers all but type 15A.
- Nine types covered 92% of isolates in children 5 years and younger.
- Reduced penicillin susceptibility was observed in 7.8% of isolates, associated with types 6B, 9V, and 19A; full resistance was most frequent in 1995 (type 9V).
- Reduced susceptibility rates were 19.5% for trimethoprim-sulfamethoxazole and ≤4.5% for other tested antimicrobials.
Conclusions:
- Current vaccines cover over 90% of invasive pneumococcal infections in individuals over 2 years of age.
- New conjugate vaccines are under development for young children.
- The observed high frequency of antimicrobial resistance underscores the need for enhanced global control strategies, including improved vaccine utilization.