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. 2024 May 24;50(5):135-143.
doi: 10.14745/ccdr.v50i05a03.

Invasive group A streptococcal disease surveillance in Canada, 2021-2022

Alyssa R Golden  1 , Averil Griffith  1 , Gregory J Tyrrell  2 , Julianne V Kus  3   4 , Allison McGeer  5 , Marc-Christian Domingo  6 , Linda Hoang  7 , Jessica Minion  8 , Paul Van Caeseele  9 , Hanan Smadi  10 , David Haldane  11 , Yang Yu  12 , Xiaofeng Ding  13 , Laura Steven  14 , Jan McFadzen  15 , Courtney Primeau  16 , Kristyn Franklin  16 , Irene Martin  1
Affiliations

Invasive group A streptococcal disease surveillance in Canada, 2021-2022

Alyssa R Golden et al. Can Commun Dis Rep. .

Abstract

Background: Invasive group A streptococcal (iGAS, Streptococcus pyogenes) disease has been a nationally notifiable disease in Canada since 2000. This report summarizes the demographics, emm types, and antimicrobial resistance of iGAS isolates collected in Canada in 2021 and 2022.

Methods: The Public Health Agency of Canada's National Microbiology Laboratory collaborates with provincial and territorial public health laboratories to conduct national surveillance of invasive S. pyogenes. Emm typing was performed using the Centers for Disease Control and Prevention emm sequencing protocol or extracted from whole-genome sequencing data. Antimicrobial susceptibilities were determined using Kirby-Bauer disk diffusion according to Clinical and Laboratory Standards Institute guidelines or predicted from whole-genome sequencing data based on the presence of resistance determinants.

Results: Overall, the incidence of iGAS disease in Canada was 5.56 cases per 100,000 population in 2021, decreasing from the peak of 8.6 cases per 100,000 population in 2018. A total of 2,630 iGAS isolates were collected during 2022, representing an increase from 2021 (n=2,179). In particular, there was a large increase in isolates collected from October to December 2022. The most predominant emm type overall in 2021 and 2022 was emm49, at 21.5% (n=468) and 16.9% (n=444), respectively, representing a significant increase in prevalence since 2018 (p<0.0001). The former most prevalent type, emm1, increased from 0.5% (n=10) in 2021 to 4.8% (n=125) in 2022; similarly, emm12 increased from 1.0% (n=22) in 2021 to 5.8% (n=151) in 2022. These two types together accounted for almost 25% of isolates collected in late 2022 (October to December). Antimicrobial resistance rates in 2021 and 2022 included: 14.9%/14.1% erythromycin resistance, 4.8%/3.0% clindamycin resistance, and <1% chloramphenicol resistance.

Conclusion: The increase of iGAS isolates collected in Canada is an important public health concern. Continued surveillance of iGAS is critical to monitor expanding emm types and antimicrobial resistance patterns.

Keywords: Canada; Streptococcus pyogenes; antimicrobial resistance; emm; group A Streptococcus; iGAS; surveillance.

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Conflict of interest statement

Competing interests None.

Figures

Figure 1
Figure 1
Annual incidencea rates of invasive Streptococcus pyogenes cases in Canada, 2011–2021 a Cases per 100,000 population
Figure 2
Figure 2
Number of invasive Streptococcus pyogenes isolates collected each quartera for children younger than 15 years and patients 15 years of age and olderb, 2018–2022 Abbreviation: Qtr, quater a Qtr1, January to March; Qtr 2, April to June; Qtr 3, July to September; Qtr 4, October to December; all month ranges are inclusive b Yearly isolate counts include those where no age was given
Figure 3
Figure 3
Prevalence of invasive Streptococcus pyogenes emm types in Canada, 2018–2022a,b a Number of isolates for 2018, 2019, 2020, 2021 and 2022, respectively b For emm types with an overall (2018–2022) N≥30: up or down arrows indicate statistically significant trends toward increasing or decreasing prevalence for the 2018–2022 timespan, using the chi-squared test for trend. Emm types with no arrow either did not demonstrate a statistically significant trend, or did not have an overall N≥30
Figure 4
Figure 4
Number of invasive Streptococcus pyogenes isolates collected each quartera for emm1, emm12 and all other emm typesb, 2018–2022 Abbreviation: Qtr, quater a Qtr1, January to March; Qtr 2, April to June; Qtr 3, July to September; Qtr 4, October to December; all month ranges are inclusive b Yearly isolate counts include those where no age was given
Figure 5
Figure 5
Regional distribution of invasive Streptococcus pyogenes isolatesa collected in A) 2021, and B) 2022, by emm type a Number of isolates in the Western, Central, Eastern, and Northern regions of Canada, respectively
Figure 6
Figure 6
Antimicrobial resistance of invasive Streptococcus pyogenes in Canada, 2018–2022 Abbreviations: CHL-R, chloramphenicol-resistant; CLI-R, constitutively clindamycin-resistant; ERY-R, erythromycin-resistant
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