Antimicrobial Susceptibility Profiles of Neisseria Gonorrhoeae in British Columbia, Canada, 2023

Introduction: Nowadays, molecular testing is the gold standard for laboratory diagnosis of gonorrhea due to its superior sensitivity compared to culture. However, unlike culture, specimens collected for molecular testing cannot have susceptibility testing performed. The current study aimed to show the antimicrobial susceptibility profiles of Neisseria gonorrhoeae isolates identified by culture in British Columbia (BC) communities. The data helps answering whether the Canadian Guidelines on Sexually Transmitted Infections empiric preferred treatment (ceftriaxone monotherapy) or alternative treatment (cefixime plus doxycycline or cefixime plus azithromycin) require amendment.

Methods: An audit was conducted on the susceptibility profiles of all culture-positive Neisseria gonorrhoeae isolates identified by LifeLabs BC regional microbiology laboratories, connected with 129 community collection centres, the largest network in the province of British Columbia, Canada. In 2023, 98 culture-positive Neisseria gonorrhoeae isolates underwent antimicrobial susceptibility testing in the provincial laboratory. Their results were interpreted using the Clinical and Laboratory Standard Institute (CLSI) M100 guidance.

Results: The susceptibilities of Neisseria gonorrhoeae isolates were as follows: azithromycin 97%, cefixime 100%, ceftriaxone 100%, ciprofloxacin 27%, penicillin 7%, and tetracycline 39%. As per CLSI, organisms that are susceptible to tetracycline are also considered susceptible to doxycycline and minocycline.

Conclusion: The preferred treatment of ceftriaxone with monotherapy is likely effective against Neisseria gonorrhoeae in the BC communities as 100% sensitivity was observed. Combination therapy with cefixime and azithromycin are also likely effective as 100% and 97% sensitivities were observed, respectively. Doxycycline should not be recommended as a monotherapy treatment or post-exposure prophylaxis of Neisseria gonorrhoeae, as its sensitivity was only 39%. Penicillin and ciprofloxacin did not appear to be effective treatment options in most cases.