National Surveillance of Antimicrobial Susceptibilities of Neisseria gonorrhoeae in Canada: Annual Summary 2017
Executive summary
This report consists of laboratory surveillance data for Neisseria gonorrhoeae isolates submitted by provincial microbiology laboratories to the National Microbiology Laboratory (NML) from 2013 – 2017.
The Canadian reported rate of gonorrhea is on the rise and has more than doubled from 21.8 per 100,000 in 2001 to 65.4 per 100,000 in 2016. Gonorrhea is the second most commonly reported bacterial sexually transmitted infection in Canada with 23,708 cases reported in 2016.
Over time, N. gonorrhoeae has acquired resistance to many antibiotics such as penicillin, tetracycline, erythromycin and ciprofloxacin. Antimicrobial resistance in N. gonorrhoeae is a serious threat to effective treatment of gonococcal infections. In 2017, routine surveillance confirmed the first ceftriaxone resistant N. gonorrhoeae in Canada.
In 2017, a total of 5,290 N. gonorrhoeae isolates were cultured and tested in public health laboratories across Canada; 2,870 of these were submitted to the NML for antimicrobial susceptibility testing (AST). AST data for an additional 1,273 N. gonorrhoeae isolates was submitted by provincial public health laboratories and included in the analysis. The total number of isolates cultured in all provinces was used as the denominator to calculate resistance proportions.
The proportion of multi-drug resistant (MDR)-GC increased from 4.4% (139/3,195) in 2013 to 12.2% (646/5,290) in 2017 (Figure A). These percentages represent the proportion of isolates with decreased susceptibility to the cephalosporins or resistance to azithromycin, along with resistance to at least two other antimicrobials.
From 2013 to 2017, there were only 12 N. gonorrhoeae isolates identified in Canada that had decreased susceptibility to a cephalosporin plus resistance to azithromycin as well as resistance to at least two other antimicrobials. These isolates, defined as XDR-GC, decreased from 0.3% (8/3,195) in 2013 to 0% (0/5,290) in 2017 (Figure A).
- Footnote 1
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Percentage based on total number of isolates tested nationally: 2013=3,195; 2014=3,809; 2015=4,190; 2016=4,538; 2017=5,290.
Figure A - Text description
| Year (number of cultures tested nationally) | MDR (%) | XDR (%) | MDR (n) | XDR (n) |
|---|---|---|---|---|
| 2013 (N=3,195) | 4.2% | 0.3% | 135 | 8 |
| 2014 (N=3,809) | 5.3% | 0.03% | 203 | 1 |
| 2015 (N=4,190) | 8.6% | 0.05% | 361 | 2 |
| 2016 (N=4,538) | 8.9% | 0.02% | 406 | 1 |
| 2017 (N=5,290) | 12.2% | 0% | 646 | 0 |
Isolates with decreased susceptibility to cefixime (MIC ≥ 0.25 mg/L) decreased from 1.8 % in 2013 (53/3,195) to 0.6% (31/5,290) in 2017 (Figure B).
Isolates with decreased susceptibility to ceftriaxone (MIC ≥ 0.125 mg/L) decreased from 3.5% (112/3,195) in 2013 to 0.5% (29/5,290) in 2017 (Figure B).
The proportion of azithromycin resistant (MIC ≥ 2mg/L) N. gonorrhoeae isolates increased from 1.2% (37/3,195) in 2013 to 11.7% (620/5,290) in 2017 (Figure B).
- Footnote 1
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Percentage based on total number of isolates tested nationally: 2013=3,195; 2014=3,809; 2015=4,190; 2016=4,538; 2017=5,290.
Figure B - Text description
| Antibiotic | Percentage of resistance or decreased susceptibility | ||||
|---|---|---|---|---|---|
| 2013 | 2014 | 2015 | 2016 | 2017 | |
| Azithromycin | 1.16% | 3.33% | 4.73% | 7.18% | 11.7% |
| Cefixime | 1.75% | 1.10% | 1.91% | 0.31% | 0.6% |
| Ceftriaxone | 3.51% | 2.65% | 3.46% | 1.76% | 0.5% |
No isolates with combined azithromycin resistance and decreased susceptibility to cefixime and/or ceftriaxone were detected in Canada in 2017.
In 2017, 50.1% (2,652/5,290) of isolates were resistant to ciprofloxacin; 31.0% (1,642/5,290) of the isolates were resistant to erythromycin; 11.7% (619/5,290) were resistant to penicillin; and 45.9% (2,429/5,290) were resistant to tetracycline.
N. gonorrhoeae isolates submitted to the NML were also analyzed by molecular genotyping using the N. gonorrhoeae multi-antigen sequence type (NG-MAST) method. In 2017, 468 different sequence types (STs) were identified among the 2,853 isolates with STs identified and the most common sequence types were ST-12302 (24.1%), ST-5985 (7.5%), and ST-14698 (5.5%).
ST-12302 increased from 4.3% of all isolates in 2015 to 10.5% in 2016 and to 24.1% in 2017; the isolates were primarily identified in central Canada. ST-12302 isolates were resistant to multiple drugs with over 50% also resistant to azithromycin (Figure C).
- Footnote 1
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A total of 292 sequence types were identified in 2013, 378 sequence types in 2014, 396 sequence types in 2015, 490 sequence types in 2016 and 468 sequence types in 2017. Only the most prevalent sequence types of 2013 to 2017 are represented in this graph.
Figure C - Text description
| NG-MAST | Year | EryR +/or TetR +/or PenR | CipR with or without resistance to other antibiotics | TRNG with or without resistance to other antimicrobials | CeDS +/or CxDS with resistance to other antimicrobials | AziR/EryR and AziR/CipR/EryR with resistance to other antimicrobials |
|---|---|---|---|---|---|---|
| ST-12302 | 2013 | - | - | - | - | - |
| 2014 | - | - | - | - | - | |
| 2015 | - | 3 | - | - | 110 | |
| 2016 | - | 84 | - | - | 240 | |
| 2017 | - | 312 | - | - | 375 | |
| ST-5985 | 2013 | - | 1 | 70 | - | - |
| 2014 | 9 | - | 286 | - | - | |
| 2015 | 2 | 4 | 395 | - | - | |
| 2016 | - | 58 | 309 | - | - | |
| 2017 | 3 | 20 | 193 | - | - | |
| ST-14698 | 2013 | - | - | - | - | - |
| 2014 | - | - | - | - | - | |
| 2015 | - | - | - | - | - | |
| 2016 | - | 6 | - | - | 6 | |
| 2017 | 37 | - | - | 119 | ||
| ST-10451 | 2013 | - | 8 | - | 2 | - |
| 2014 | - | 166 | - | - | 40 | |
| 2015 | - | 119 | - | 1 | 34 | |
| 2016 | - | 167 | - | - | 10 | |
| 2017 | 1 | 143 | - | - | - |
For more details on the report and its key findings, please email: phac.nml.strepsti-lnm.strepits.aspc@canada.ca.
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