National surveillance of antimicrobial susceptibilities of Neisseria gonorrhoeae annual summary 2018

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 2014 – 2018 as part of the Gonococcal Antimicrobial Surveillance Program (GASP – Canada).
The Canadian reported rate of gonorrhea is on the rise and has more than doubled from 21.8 per 100,000 in 2001 to 79.5 cases per 100,000 in 2017. Gonorrhea is the second most commonly reported bacterial sexually transmitted infection in Canada with 29,034 cases reported in 2017.
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 2018, 7 extensively drug resistant gonorrhea isolates (XDR-GC; decreased susceptibility to a cephalosporin plus resistance to azithromycin as well as resistance to at least two other antimicrobials) were identified in Canada posing a potential threat to successful treatment.
In 2017, routine surveillance confirmed the first ceftriaxone resistant N. gonorrhoeae in Canada. In 2018, three ceftriaxone resistant cases were identified in Canada. All were associated with travel to South-East Asia.
In 2018, a total of 5,607 N. gonorrhoeae isolates were cultured and tested in public health laboratories across Canada; 3,426 of these were submitted to the NML for antimicrobial susceptibility testing (AST). AST data for an additional 1,517 N. gonorrhoeae isolates were 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 4.5% (172/3,809) in 2014 to 12.2% (645/5,290) in 2017 and then decreased to 8.0% (448/5,607) in 2018 (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 2014 to 2016, there were only 4 XDR-GC identified in Canada; none were found in 2017. In 2018, seven [1% (7/5,607)] isolates were classified as XDR-GC (Figure A).

placeholder image — **Figure A. Trends of MDR-GC and XDR-GC *Neisseria gonorrhoeae* in Canada from 2014 to 2018^{Footnote a}**

Isolates with decreased susceptibility to cefixime (MIC ≥ 0.25 mg/L) decreased from 1.0% (38/3,809) in 2014 to 0.5% (27/5,607) in 2018 (Figure B).
Isolates with decreased susceptibility to ceftriaxone (MIC ≥ 0.125 mg/L) decreased from 2.5% (96/3,809) in 2014 to 0.6% (31/5,607) in 2018 (Figure B).
The proportion of azithromycin resistant (MIC ≥ 2mg/L) N. gonorrhoeae isolates increased from 3.4% (128/3,809) in 2014 to 7.6% (427/5,607) in 2018 (Figure B).

Year (number of cultures tested nationally)	MDR (%)	XDR (%)	MDR (n)	XDR (n)
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
2018 (N=5,607)	8.0%	0.12%	446	7

Three high-level azithromycin resistant (MIC ≥ 256 mg/L) N. gonorrhoeae isolates were identified in 2018 (QC, n=2; BC, n=1).

In 2018, 57.3% (3,214/5,607) of isolates were resistant to ciprofloxacin; 56.0% (1,914/3,417) of the isolates were resistant to erythromycin; 9.2% (356/3,882) were resistant to penicillin; and 47.1% (2,640/5,607) 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 2018, 505 different sequence types (STs) were identified among the 3,375 isolates with STs identified and the most common sequence types were ST-12302 (18.2%), ST-14994 (16.6%), and ST-5985 (5.8%).
ST-12302 increased from 4.3% of all isolates in 2015 to 24.1% in 2017 and has now decreased to 18.2% in 2018. In 2017, the isolates were primarily identified in central Canada; in 2018, approximately 10% were identified in western provinces (Figure C).

Antibiotic	2014	2015	2016	2017	2018
Ceftriaxone - (DS) Decreased Susceptibility	96 (2.5%)	144 (3.4%)	80 (1.8%)	30 (0.6%)	31 (0.6%)
Cefixime - (DS) Decreased Susceptibility	38 (1%)	79 (1.9%)	14 (0.3%)	32 (0.6%)	27 (0.5%)
Azithromycin - (R) Resistant	128 (3.4%)	198 (4.7%)	327 (7.2%)	613 (11.6%)	427 (7.6%)

ST-14994 was newly identified in 2017 (2.1% (60/2,875) and increased dramatically to 16.6% (562/3,379) in 2018 (Figure C). These isolates are resistant to multiple drugs including ciprofloxacin with approximately 5% of them having resistance to azithromycin as well.

NG-MAST	Year	CipR with or without other resistances	TRNG with or without other resistances	AziR/EryR and AziR/CipR/EryR with other resistances
ST-12302	2014	N/A	N/A	N/A
N/A	2015	3	N/A	110
N/A	2016	84	N/A	240
N/A	2017	312	N/A	375
N/A	2018	390	N/A	225
ST-14994	2014	N/A	N/A	N/A
N/A	2015	N/A	N/A	N/A
N/A	2016	N/A	N/A	N/A
N/A	2017	60	N/A	N/A
N/A	2018	537	N/A	23
ST-5985	2014	N/A	322	N/A
N/A	2015	6	419	N/A
N/A	2016	58	309	N/A
N/A	2017	20	193	N/A
N/A	2018	N/A	194	N/A

For more details on the report and its key findings, please email: phac.nml.strepsti-lnm.strepits.aspc@canada.ca.

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Date modified:: 2020-06-01

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National surveillance of antimicrobial susceptibilities of Neisseria gonorrhoeae annual summary 2018

Executive summary

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