The percentage of gonorrhea cases in Ontario resistant to a common class of antibiotics has soared, and researchers say that finding reinforces national guidelines advising against the use of those drugs to treat the infections.
In Monday's online issue of the Canadian Medical Association Journal, Dr. Susan Richardson of Toronto's Hospital for Sick Children and her colleagues reported that antibiotic-resistant gonorrhea increased to a rate of 28 per cent in 2006 from two per cent in 2001.
'While we work on different drugs to combat some of these multi-resistant bugs, people need to take protection into their own hands.' — Dr. Susan Richardson
The magnitude of the rate of resistance to quinolone antibiotics was "unusually high" for North America, the researchers said.
"Really there needs to be a Canada-wide surveillance project that is probably ongoing into the future to keep tabs on what's happening to resistance for this important public health pathogen," said Richardson, head of microbiology at Sick Kids.
"But the likelihood is that as Ontario is a hub for a lot of tourism, and travel and business etc., that these resistant strains will be imported from various places around the world and then spread from there, from Toronto, throughout the rest of Canada, so that the rates would be expected to rise over time elsewhere."
After several years of declining rates, infections from Neisseria gonorrhoeae bacteria are on the rise in Canada and many other countries.
Complications can result
The infection can be transmitted through oral, genital or anal sex with an infected person. If left untreated, the disease can cause other problems, including sterility, a greater susceptibility to HIV and serious blood, joint and immune complications.
In the latest study, researchers analyzed records from the Public Health Laboratory of the Ontario Agency for Health Protection and Promotion in Toronto and the National Microbiology laboratory in Winnipeg to track how many bacterial cultures were resistant to quinolone antibiotics.
The most important protection against any sexually transmitted infection is to practise safe sex, Richardson stressed.
"Safe sex, barrier precautions using condoms are very important," said Richardson, who did the research in her capacity as a consultant to the Ontario Agency for Health Protection and Promotion.
"And probably the use of them and people's concern about that might be dropping off in recent years. That may be related to this rise we're seeing.
"While we work on different drugs to combat some of these multi-resistant bugs, people need to take protection into their own hands."
The study's authors said infections in heterosexual men appeared to have contributed significantly to the antibiotic resistance rate.
Advantage of conventional testing
Since 2006, guidelines have cautioned doctors against using quinolone antibiotics such as ciprofloxacin and oflloxacin. It is not known what has happened to rates of resistance in Ontario since then.
The researchers said their finding underscored the importance of following the recommendations against using quinolones to treat gonorrhea.
All samples tested in the study were susceptible to the antibiotics cefixime and cetriaxone, which suggests those drugs remain suitable, the researchers said.
In a commentary accompanying the study, Dr. John Tapsall, of the World Health Organization's collaborating centre for sexually transmitted diseases in Sydney, Australia, noted that reports of resistance to cefixime and cetriaxone treatment failure have started to emerge in Japan and Hong Kong.
Ongoing testing for antibiotic resistance is necessary to ensure that gonorrhea infections that are multi-drug-resistant are quickly identified and contained, the study's authors said.
This could be a challenge as molecular testing — which takes four to six hours, compared with three to four days for conventional testing — becomes more popular.
Scientists need to grow bacteria in lab dishes to test if the bugs are resistant to antibiotics. Molecular tests use DNA to identify if a microbe is present, but can't tell if it is resistant.
Dr. Tom Wong, director of community acquired infections for the Public Health Agency of Canada, said the agency is working with provincial and territorial partners to try to put together a sentinel surveillance system like the one suggested in the study.