Incidence and treatment outcomes of pharyngeal Neisseria gonorrhoeae and Chlamydia trachomatis infections in men who have sex with men: a 13-year retrospective cohort study.

BACKGROUND: This study investigated the incidence and treatment outcomes of pharyngeal Neisseria gonorrhoeae and Chlamydia trachomatis cases at a Canadian clinic that mainly serves men who have sex with men. METHODS: All patients with pharyngeal N. gonorrhoeae and C. trachomatis infections detected from 1 January 1995 through 31 December 2007 were identified. Original and test-of-cure N. gonorrhoeae culture isolates were compared using antibiotic susceptibility testing and N. gonorrhoeae multiantigen sequence typing. RESULTS: One hundred seventy-eight cases of pharyngeal N. gonorrhoeae infection and 97 cases of pharyngeal C. trachomatis infection were identified, primarily by culture methods. The mean incidence was 1.62 and 0.81 cases per 1000 visits per year for N. gonorrhoeae and C. trachomatis infection, respectively. Poisson regression modeling demonstrated a statistically significant surge of pharyngeal N. gonorrhoeae cases in 2007 after controlling for seasonal and long-term oscillation and long-term linear trends. Among patients with pharyngeal N. gonorrhoeae and C. trachomatis infection, 60.2% and 84.3%, respectively, would have been missed by relying on urine and urethral testing. Nine percent of patients with pharyngeal N. gonorrhoeae and 4.3% of patients with pharyngeal C. trachomatis infection who underwent test-of-cure procedures had at least 1 positive result. Antibiograms were not different in 8 of 10 pretreatment and posttreatment N. gonorrhoeae isolate pairs. N. gonorrhoeae multiantigen sequence typing results were identical in 2 of these cases. Public health records documented abstinence in both individuals. CONCLUSIONS: Nine percent of cases with pharyngeal N. gonorrhoeae and 4.3% of cases with pharyngeal C. trachomatis infection that underwent tests of cure had positive results. Available typing results suggest antibiotic treatment failure rather than reinfection. Specific antibiotic treatment regimens for pharyngeal N. gonorrhoeae and C. trachomatis infections need to be developed and formally evaluated.

Prevalence of and risk factors for quinolone-resistant Neisseria gonorrhoeae infection in Ontario.

BACKGROUND: Quinolone-resistant Neisseria gonorrhoeae has swiftly emerged in Canada. We sought to determine its prevalence in the province of Ontario and to investigate risk factors for quinolone-resistant N. gonorrhoeae infection in a Canadian setting. METHODS: We used records from the Public Health Laboratory of the Ontario Agency for Health Protection and Promotion in Toronto, Ontario, and the National Microbiology Laboratory in Winnipeg, Manitoba, to generate epidemic curves for N. gonorrhoeae infection. We extracted limited demographic data from 2006 quinolone-resistant N. gonorrhoeae isolates and from a random sample of quinolone-susceptible isolates. We also extracted minimum inhibitory concentrations for commonly tested antibiotics. RESULTS: Between 2002 and 2006, the number of N. gonorrhoeae infections detected by culture decreased by 26% and the number of cases detected by nucleic acid amplification testing increased 6-fold. The proportion of N. gonorrhoeae isolates with resistance to quinolones increased from 4% to 28% over the same period. Analysis of 695 quinolone-resistant N. gonorrhoeae isolates and 688 quinolone-susceptible control isolates from 2006 showed a higher proportion of men (odds ratio [OR] 3.1, 95% confidence interval [CI] 2.3-4.1) and patients over 30 years of age (OR 3.1, 95% CI 2.4-3.8) in the quinolone-resistant group. The proportion of men who have sex with men appeared to be relatively similar in both groups (OR 1.4, 95% CI 1.1-1.8). Quinolone-resistant strains were more resistant to penicillin (p < 0.001), tetracycline (p < 0.001) and erythromycin (p < 0.001). All isolates were susceptible to cefixime, ceftriaxone, azithromycin and spectinomycin. INTERPRETATION: During 2006 in Ontario, 28% of N. gonorrhoeae isolates were resistant to quinolones. Infections in heterosexual men appear to have contributed significantly to the quinolone resistance rate. Medical practitioners should be aware of the widespread prevalence of quinolone-resistant N. gonorrhoeae and avoid quinolone use for empiric therapy.