National Surveillance of Antimicrobial Susceptibilities of Neisseria gonorrhoeae – 2015

Annual Summary Report 2015

Executive Summary

This report compares laboratory surveillance data for Neisseria gonorrhoeae isolates submitted by provincial microbiology laboratories to the National Microbiology Laboratory (NML) from 2011-2015.

The Canadian reported rate of gonorrhea is on the rise and has more than doubled from 21.8 per 100,000 in 2001 to 55.4 per 100,000 in 2015. Gonorrhea is the second most commonly reported bacterial sexually transmitted infection in Canada with 19,845 cases reported in 2015.

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 2015, a total of 4,190 N. gonorrhoeae isolates were cultured in public health laboratories across Canada; 2,638 of these were submitted to the NML for antimicrobial susceptibility testing.  The total number of isolates cultured in all provinces was used as the denominator to calculate resistance proportion.   

The WHO breakpoints of decreased susceptibility to cefixime at MIC ≥ 0.25 mg/L and decreased susceptibility to ceftriaxone at MIC ≥ 0.125 mg/L (WHO, 2012) were used throughout this report.

Isolates with decreased susceptibility to cefixime have increased from 1.1% (42/3,809) in 2014 to 1.9% (80/4,190) in 2015. 

Isolates with decreased susceptibility to ceftriaxone increased from 2.7% (101/3,809) in 2014 to 3.5% (146/4,190) in 2015.

The proportion of azithromycin resistant (MIC ≥ 2 mg/L) N. gonorrhoeae isolates has been increasing steadily from 0.4% (13/3,360) in 2011 to 4.7% (198/4,190) in 2015. 

In 2015, 38.9% (1,629/4,190) of isolates were resistant to ciprofloxacin; 32.4% (1,358/4,190) of the isolates were resistant to erythromycin; 18.9% (793/4,190) were resistant to penicillin; and 56.4% (2,364/4,190) were resistant to tetracycline. 
High level, plasmid mediated tetracycline resistant N. gonorrhoeae (TRNG)  increased from 3.4% (103/3,036) in 2012 to 10.7% (407/3,809) in 2014 and to 14.4% (605/4,190) in 2015.The majority of 2015 TRNG are  ST-5985 [64.1% (388/605)].

Since 2010, all 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 2015, 396 different sequence types (STs) were identified among the 2,638 isolates tested and the most common sequence types were ST-5985, ST-2400 and ST-10451 at 15.2%, 12.2% and 5.8%, respectively. 

For more details on the report and its key findings, please email: NML.STREPSTI@phac-aspc.gc.ca