Section 2: Report on Sexually Transmitted Infections in Canada: 2012 – Gonorrhea (Neisseria gonorrhoeae)

2. Gonorrhea (Neisseria gonorrhoeae)

Gonorrhea, a bacterial infection caused by Neisseria gonorrhoeae, has been nationally notifiable since 1924. It is the second most commonly reported STI in Canada. Untreated infections can lead to complications for both sexes. There are severe consequences for females, including pelvic inflammatory disease, which often leads to chronic abdominal pain, infertility, and ectopic pregnancy. In males, untreated infections can result in epididymitis and rare cases of infertility. An uncommon complication of gonorrhea is the spread of infection to the blood stream and joints^{Footnote 30}. Like other STIs, gonorrhea increases the risk of HIV acquisition and transmission, possibly by increasing the concentration of HIV target cells in genital secretions and viral shedding^Footnote3.

2.1 National Trends

Trends over Time

Between 1991 and 1997, Canada experienced a sharp decline in the rates of reported cases of gonorrhea, followed by a steady incline through to 2004, after which rates began to fluctuate between marginal increases and decreases, possibly indicative of a stabilization of gonorrhea incidence in Canada (Figure 5). In 2012, there were a total of 12,561 cases of gonorrhea reported, corresponding to a rate of 36.2 per 100,000. The 2012 rate was a 38.9% increase from the rate of 26.0 per 100,000 in 2003. Over this ten year time frame, rates increased among both males and females; males experienced a 29.1% relative rate increase while females experienced a 53.9% relative rate increase.

Trends by Age Group and Sex

Rates of reported cases of gonorrhea in 2012 were higher among females than males at younger ages (<25 years); in contrast, among older age groups (25 years plus), males exhibited higher rates of gonorrhea (Figure 6). As seen with chlamydia, the majority of gonorrhea cases were observed among individuals under the age of 30 (67.4%). In 2012, the highest rates of gonorrhea were observed among females aged 20 to 24, followed by females aged 15 to 19. In males, the highest rates of reported cases of gonorrhea were observed among those aged 20 to 24 years, followed by those aged 25 to 29 years (148.5 and 133.1 per 100,000, respectively).

Between 2003 and 2012, rates of reported cases of gonorrhea increased among both males and females aged 10 and above. The greatest relative rate increase observed among males was in those aged 10 to 14 years (262.0%), from 0.5 to 1.7 per 100,000 (Figure 7). Over this ten year time frame, the highest relative increase observed among females was in those aged 60 and over (188.0%, from 0.2 to 0.7 per 100,000), though females in this age group exhibited the lowest rate of gonorrhea as compared to females in other age groups (Figure 8).

Trends by Province/Territory

In 2012, as in the previous year, the rate of reported cases of gonorrhea was significantly higher in the Northwest Territories (440.2 per 100,000) as compared to other jurisdictions. Gonorrhea rates exceeding the national average of 36.2 per 100,000 were also observed in Manitoba, Saskatchewan and Alberta (107.9, 93.6 and 53.1 per 100,000, respectively) (Table 3). Between 2003 and 2012, all provinces and territories experienced a relative increase in the rate of the reported cases of gonorrhea, with the exception of Northwest Territories, Ontario and Nova Scotia. The greatest relative rate increase was observed in the Yukon (156.3%), from 9.7 to 24.8 per 100,000 (Table 3).

2.2 Antimicrobial Resistance in Gonorrhea

Uncomplicated gonorrhea can be treated with oral or injected antibiotics. However, strains of gonorrhea have a tendency to evolve and become less susceptible or even resistant to treatment with antibiotics. Challenges to successful treatment arise when gonococcal infections are treated with antibiotics to which the bacteria are resistant or have decreased susceptibility. Treatment failure, further transmission of the infection, and the development of adverse consequences are likely unless the resistant organism is identified and treated appropriately.

Gonococcal resistance to penicillin, erythromycin, and tetracycline is long established, while ciprofloxacin resistance developed more recently. None of these antibiotics are currently recommended as preferred treatments by the Canadian Guidelines on Sexually Transmitted Infections^{Footnote 31}. More recently, treatment failures after use of the internationally recommended first-line cephalosporins (cefixime and ceftriaxone) in the absence of any suitable alternatives have led to fears that extensively drug-resistant gonorrhea is emerging^{Footnote 32-Footnote Footnote 35}.

There is an increasing trend to diagnose gonorrhea using urine specimens analyzed with NAAT. These specimens are easier to obtain and more acceptable to patients than traditional genital specimens (swabs). The laboratory test is also more sensitive, yielding fewer false negatives than culture. However, this shift towards non-culture-based diagnostic techniques has created challenges in monitoring antimicrobial resistance (AMR) as the number of culture specimens available for sensitivity testing is more limited; at present there is no method for testing AMR from non-culture specimens.

The NML tests gonococcal isolates for resistance to penicillin, tetracycline, spectinomycin, erythromycin, azithromycin, ciprofloxacin, cefixime, and ceftriaxone. The most current data available (2012) showed that 30.3% of cultured strains were resistant to tetracycline, 28.52% to ciprofloxacin, 23.12% to erythromycin, 20.26% to penicillin, and 0.86% to azithromycin (Figure 9). There were no strains resistant to spectinomycin, cefixime, or ceftriaxone, though 2.2% of isolates were identified as having decreased susceptibility to cefixime and 5.5% were identified as having decreased susceptibility to ceftriaxone^{Footnote 36}.

Canadian gonococcal resistance surveillance is a collaborative effort between the NML and provincial and territorial laboratories. Submission to the NML of gonococcal isolates that have decreased susceptibility to at least one antibiotic is voluntary and not standardized across the country. Data received through laboratory-based surveillance are restricted to key demographic variables; risk factor information is not available. Furthermore, culture diagnosis for gonorrhea is typically performed in STI clinics and among higher-risk patients, limiting the representativeness of available surveillance data. The NML publishes the results of this laboratory-based surveillance annually. Efforts are under way to conduct enhanced surveillance of AMR in gonorrhea, to provide an informative and representative picture of this issue in Canada.

2.3 Summary

Although the rate of reported cases of gonorrhea in Canada is considerably lower than that of chlamydia, there are similar overall trends in the two infections. The increases in rates since the late 1990s may be at least partly explained by the factors thought to affect chlamydia rates, such as the move to more sensitive testing methods and improved case finding^{Footnote 12}.

In contrast with chlamydia, observed rates of gonorrhea were higher in males overall, albeit with a smaller discrepancy between the sexes. Analysis of age and sex simultaneously demonstrates that like chlamydia, rates of reported cases of gonorrhea are much higher in females than males in younger age groups; however, rates become approximately equal at a younger age (20 to 24 years), and in those aged 25 years and older, male rates exceed those among females. Such differences may be partially explained by evidence that males are more likely to show signs of gonorrhea infection^{Footnote 37}. Presence of symptoms likely influences care seeking behaviours and could contribute to the greater number of cases detected among males^{Footnote 37}. In addition, increases in certain sex practices among MSM have been associated with increases in gonorrhea in this population^{Footnote 38Footnote 39}.

The overall rates of reported cases of gonorrhea were substantially lower in Canada at 36.2 per 100,000 compared to the United States (107.5 per 100,000)^{Footnote 22Footnote 23} Australia (58.9 per 100,000)^{Footnote 24}, and England (48.1 per 100,000)^{Footnote 25}. There was considerable variability in the differences observed across sexes; in Australia and England, gonorrhea rates were more than twice as high among males as compared to females, while the differences between sexes in Canada and the United States were less pronounced.

Antimicrobial resistance may also play a significant role in the increase in reported rates of gonorrhea, as the proportion of isolates resistant to a number of antibiotics has increased over time, which may lead to treatment failure and a longer duration of infectiousness in affected patients. The susceptibility of N. gonorrhoeae to first-line treatments has decreased ^{Footnote 36,Footnote 40,Footnote 41}. Emerging antimicrobial resistance in gonorrhea has led to changes in treatment recommendations across Canada and elsewhere^{Footnote 31,Footnote 42-Footnote 45}. The potential for a link between antimicrobial resistance and rising rates of reported cases of gonorrhea is of utmost concern.

Figure 5: Overall and sex-specific rates of gonorrhea, 1991 to 2012, Canada

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Figure 6: Rates of reported gonorrhea by sex and age group, 2012, Canada

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Figure 7: Rates of reported gonorrhea in males by age group, 2003 to 2012, Canada

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Figure 8: Rates of reported gonorrhea in females by age group, 2003 to 2012, Canada

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Figure 9: Antimicrobial resistance^{Footnote 1. Footnote 2.} of Neisseria gonorrhoeae strains tested in Canada, 1999 to 2012

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