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Updated: Feb 8, 2026
Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
Published on: September 25, 2014
Antimicrobial susceptibility testing of invasive isolates of Streptococcus pneumoniae from Canadian patients: the
James A Karlowsky1,2, Heather J Adam1,2, Alyssa R Golden1
1Department of Medical Microbiology, Max Rady College of Medicine, University of Manitoba, Room 543 - 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada.
Objectives:
To assess antimicrobial susceptibility for 14 agents tested against 6001 invasive isolates of Streptococcus pneumoniae cultured from invasive patient samples from 2011 to 2015 as a part of the annual SAVE study.
Methods:
Isolates of S. pneumoniae were tested using the standard CLSI broth microdilution method (M07-A10, 2015) with MICs interpreted by CLSI M100 27th Edition (2017) MIC breakpoints.
Results:
From 2011 to 2015, small but significant increases (P ≤ 0.05) in the percentage susceptibility for penicillin (interpreted by all three CLSI MIC breakpoint criteria) (increase of 1.7%-3.2%), clindamycin (3.1%) and ceftriaxone (interpreted by non-meningitis and meningitis CLSI MIC breakpoint criteria) (1.1%-1.5%) were observed. Susceptibility rates for clarithromycin and other commonly tested antimicrobial agents remained unchanged (P > 0.05) over the 5 year period. Isolates with an MDR phenotype (resistance to three or more antimicrobial agent classes) decreased significantly (P < 0.001) from 8.5% in 2011 to 5.6% in 2015. Antimicrobial susceptibility rates were not generally associated (P > 0.05) with patient gender (exception: clarithromycin) but were associated (P ≤ 0.05) with patient age (chloramphenicol and clindamycin) or specimen source (penicillin, doxycycline, trimethoprim/sulfamethoxazole and clindamycin), as well as geographic location in Canada and concurrent resistance to penicillin or clarithromycin.
Conclusions:
The in vitro susceptibility of invasive isolates of S. pneumoniae in Canada to penicillin, clindamycin and ceftriaxone increased from 2011 to 2015, coincident with a significant decrease in MDR phenotypes.
Insights
Antimicrobial susceptibility to penicillin, clindamycin, and ceftriaxone increased in invasive Streptococcus pneumoniae isolates in Canada between 2011 and 2015. Multidrug-resistant phenotypes also significantly decreased during this period.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Public Health
Background:
- Streptococcus pneumoniae is a leading cause of invasive bacterial diseases globally.
- Monitoring antimicrobial resistance patterns is crucial for effective treatment and public health strategies.
- The SAVE study annually tracks invasive bacterial isolates in Canada.
Purpose of the Study:
- To evaluate the in vitro antimicrobial susceptibility of invasive Streptococcus pneumoniae isolates in Canada.
- To assess trends in susceptibility to 14 antimicrobial agents from 2011 to 2015.
- To determine changes in multidrug-resistant (MDR) phenotypes over the study period.
Main Methods:
- Analysis of 6001 invasive Streptococcus pneumoniae isolates collected between 2011 and 2015.
- Antimicrobial susceptibility testing using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method.
- Interpretation of Minimum Inhibitory Concentrations (MICs) according to CLSI M100 27th Edition (2017) breakpoints.
Main Results:
- Significant increases in susceptibility were observed for penicillin (1.7%-3.2%), clindamycin (3.1%), and ceftriaxone (1.1%-1.5%).
- Susceptibility rates for clarithromycin and other agents remained stable.
- A significant decrease in MDR phenotypes was noted, from 8.5% in 2011 to 5.6% in 2015.
Conclusions:
- In vitro susceptibility of invasive S. pneumoniae to penicillin, clindamycin, and ceftriaxone improved in Canada from 2011 to 2015.
- This improvement coincided with a significant reduction in multidrug-resistant S. pneumoniae isolates.
- These findings highlight positive trends in antimicrobial resistance for key pathogens in Canada.
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