Surveillance of antibiotic-resistant strains of Neisseria gonorrhoeae in the province of Quebec

Highlights in 2022

In 2022, the monitoring program highlighted the following facts:

Case reports and laboratory tests for detection of infections:

• The 1766 strains which were retained for analysis (1 strain/person/14 days)
  correspond to 22% of declared cases of gonococcal infection in the register of notifiable diseases (MADO).
  • The 1497 strains isolated from men correspond to 25% of the 6122 cases reported in men;
  • The 268 strains isolated from women correspond to 14% of the 1925 cases reported in women;
  • One strain was isolated from a person whose gender information was not available.
• The proportion of strains tested at the LSPQ was at least 20% of the cases declared in 13 of the 15 regions having declared 10 or more cases of gonococcal infection;
• In 2022:
• The proportion of reported cases detected solely by nucleic acid amplification testing (NAAT) was 78% (range 73-79% since 2016);
• The positivity rate among cultured strains was higher than in previous years (7.2%, or 3 times higher than in 2019), while that among NAAT tests was relatively stable (1, 2%);

Résistance :

• In 2022, the strains of N. gonorrhoeae were analyzed to establish the minimum inhibitory concentrations (MIC), by the agar dilution method, for the following five antibiotics: ciprofloxacin, azithromycin, cefixime, ceftriaxone and gentamicin;
• All strains received (n=1954) were analyzed for sensitivity to these antibiotics;
• 79% of the strains for which the antibiogram could be carried out showed resistance to at least one of the antibiotics tested (1392/1764);
• Resistance to ciprofloxacin (MIC ≥ 1 mg/L) has fluctuated over the years. It was between 32 and 48% in 2010-2015, between 60 and 74% in 2016-2020 then decreased to 50% in 2021 and 2022;
  • The prevalence of ciprofloxacin resistance among strains isolated from women (132/268; 49%) is similar to that of strains isolated from men (750/1495; 50%).
• Resistance toazithromycin (MIC ≥ 2 mg/L) has been increasing at a worrying rate. While it was less than 2% between 2010 and 2013, it increased to 7% in 2014 and 31% in 2017, after a period of stabilization between 2018-2020 (24-28%), it increased again in 2021 (39%), reaching a new peak of 44% in 2022;
  • Resistant strains have been found in 14 of the 18 regions of Quebec.
  • The prevalence of azithromycin resistance is similar for strains isolated from women (120/268; 45%) as for those isolated from men (660/1495; 44%).
  • Among azithromycin-resistant strains, 35% (271/781) were also resistant to ciprofloxacin.
• From 2010 to 2020, a few strains not susceptible to cefixime were identified (2 in 2015, 1 in 2016, 3 in 2017, 12 in 2019 and 7 in 2020). In 2021 and 2022, all strains were susceptible to cefixime;
• In 2022, although no strain not susceptible to cephalosporins of 3^e generation (C3G) has been identified, strains for which the MIC approaches the threshold of non-susceptibility to C3G, or corresponding to reduced sensitivity to C3G according to WHO criteria, have been detected:
  • Cefixime: 56 strains (3.2 %) : CMI = 0.12 mg/L (n = 51) and CMI = 0.25 mg/L (n = 5).
    • These 56 strains were isolated from 43 men and 13 women respectively.
    • The 5 strains whose MIC to cefixime was 0.25 mg/L correspond to reduced sensitivity.
  • Ceftriaxone : two strains had reduced sensitivity (MIC = 0.12 mg/L and 0.25 mg/L, respectively).