Antimicrobial susceptibilities of Neisseria gonorrhoeae in Canada, 2021

Abstract

Background: In Canada, gonorrhea is the second most prevalent bacterial sexually transmitted infection. The Gonococcal Antimicrobial Surveillance Programme (GASP - Canada), a passive surveillance system monitoring antimicrobial resistance in Neisseria gonorrhoeae in Canada since 1985, is the source for this summary of demographics, antimicrobial resistance and N. gonorrhoeae multi-antigen sequence typing (NG-MAST) of gonococcal isolates collected in Canada in 2021.

Methods: Provincial and territorial public health laboratories submitted N. gonorrhoeae cultures and data to the National Microbiology Laboratory in Winnipeg as part of the surveillance system. The antimicrobial resistance and molecular type of each isolate received were determined.

Results: In total, 3,439 N. gonorrhoeae cultures were received from laboratories across Canada in 2021, a 9.9% increase since 2020 (n=3,130). Decreased susceptibility to cefixime increased significantly (p<0.001) in 2021 (1.5%) compared to 2017 (0.6%). No significant change in decreased susceptibility to ceftriaxone was detected between 2017 and 2021 (0.6%) (p>0.001); however, one ceftriaxone-resistant isolate was identified. Azithromycin resistance decreased significantly (p<0.001) in 2021 (7.6%) compared to 2017 (11.7%); however, there was a significant increase (p<0.001) in the proportion of cultures with an azithromycin minimum inhibitory concentration of at least 1 mg/L (2017=22.2% to 2021=28.1%). In 2021, NG-MAST-19875 (15.3%) was the most prevalent sequence type in Canada; 20.3% of isolates with this sequence type were resistant to azithromycin.

Conclusion: The spread of antimicrobial-resistant gonorrhea is a significant public health concern. The continued regional and national surveillance of antimicrobial resistance in N. gonorrhoeae is essential in ensuring effective treatment therapies are recommended.

Keywords: Neisseria gonorrhoeae; antimicrobial resistance; antimicrobial susceptibility; gonorrhea; national surveillance system; passive surveillance.

Figure 1

Reported Neisseria gonorrhoeae cases in Canada, 2011–2020^a,b Abbreviation: NAAT, nucleic acid amplification testing ^a Approximately 10% of all gonorrhea cases were diagnosed by culture in Canada in 2020. The rest was detected using nucleic acid amplification test technology. The number of reported cases for 2021 had not yet been determined at the time of publication ^b The number of gonorrhea cases diagnosed by nucleic acid amplification testing is determined by subtracting the number of cultures tested across Canada from the number of gonorrhea cases reported ((1))

Figure 2

Percentage of Neisseria gonorrhoeae cultures with decreased susceptibility to cefixime by province, 2017–2021^{a,b a} Provinces included in this figure are only those that submitted at least one culture to the National Microbiology Laboratory that had decreased susceptibility to cefixime ^b Denominators used for the calculations of the percentages are the number of cultures tested in each province (Table S4)

Figure 3

Percentage of Neisseria gonorrhoeae cultures with decreased susceptibility to ceftriaxone by province, 2017–2021^{a,b a} Provinces included in this figure are only those that submitted at least one culture to the National Microbiology Laboratory that had decreased susceptibility to ceftriaxone ^b Denominators used for the calculations of the percentages are the number of cultures tested in each province (Table S4)

Figure 4

Percentage of azithromycin-resistant Neisseria gonorrhoeae cultures by province, 2017-2021^{a,b a} Provinces included in this figure are only those that submitted at least one culture to the National Microbiology Laboratory that was azithromycin-resistant. Newfoundland and Labrador had one azithromycin-resistant isolate in 2019 ^b Denominators used for the calculations of the percentages are the number of cultures tested in each province (Table S4)

Figure 5

Trends of the percentage of azithromycin minimum inhibitory concentrations for Neisseria gonorrhoeae at the susceptibility of breakpoints^{a a} Breakpoints of at least 1 mg/L and at least 2 mg/L

Figure 6

Percentage of antimicrobial resistance of Neisseria gonorrhoeae isolates tested in Canada, 2017–2021^{a,b a} Percentages are based on the total number of isolates tested nationally: 2017=5,290; 2018=5,607; 2019=4,859; 2020=3,130; 2021=3,439 ^b Due to some provinces not testing all seven antimicrobials from 2017 to 2021, penicillin denominators were 3,267, 3,883, 3,822, 2,409 and 2,334, respectively; erythromycin denominators were 2,879, 3,418, 3,446, 2,025 and 2,006, respectively. In 2020 and 2021, tetracycline denominators were 2,409 and 2,334, respectively

Figure 7

Distribution of resistance characterizations within Neisseria gonorrhoeae-multi-antigen sequence typing sequence types, 2021, n=2,006^a Abbreviations: AziR, azithromycin-resistant; CeDS, cefixime decreased susceptibility; CipR, ciprofloxacin-resistant; CxDS, ceftriaxone decreased susceptibility; EryR, erythromycin resistant; PenR, penicillin-resistant; ST, sequence type; TetR, tetracycline-resistant; TRNG, tetracycline-resistant Neisseria gonorrhoeae ^a Figure does not include 33 isolates that were non-typeable. This graph represents 1,338 isolates. The remaining 635 isolates are dispersed among 260 sequence types containing 1–12 isolates each