Gonorrhea infections are on the rise but treatments for the common sexually transmitted infection are quickly running out.
New Canadian research, published in this week's edition of the Journal of the American Medical Association, shows that treatment failed in 7 per cent of patients who receive the drug cefixime. (Antibiotics are deemed ineffective once the failure rate exceeds 5 per cent.)
Cefixime is the last commercially available treatment for gonorrhea available in pill form.
"This is a scary finding," Dr. Vanessa Allen, a medical microbiologist at Public Health Ontario and lead author of the study, said in an interview.
"Once we lose this, treatment isn't just a pill any more, it's an injection."
Currently, gonorrhea is treated with a single pill, and those diagnosed with the infection are given another prescription for their sexual partner(s) as a preventive measure.
Moving from a pill to an injection will add tremendous cost and complexity to treatment, Allen said. "And if we don't have adequate treatment, we will see more complications," she said.
Pills can simply be prescribed, for the patient and his or her partner. Not all physicians will want to keep gonorrhea shots in stock at their office, so it will require patients (and their partners) to find a clinic that provides that service, all of which create barriers to treatment.
The new research was conducted in Toronto, at the Hassle Free Clinic. Researchers identified 291 patients diagnosed with gonorrhea, 133 of whom returned for a test to determine if they were cured. Cefixime treatment failed in nine patients.
In an editorial also published in JAMA, Dr. Robert Kirkcaldy of the division of STD prevention at the U.S. Centers for Disease Control and Prevention, said the findings are "deeply troubling" because they point to the emergence of antibiotic-resistant strains of the disease when there is no effective backup treatment options.
"New antibiotics for treating gonococcal infections are needed," he said. "But the antibiotic pipeline is running dry."
Kirkcaldy said the fact that drug-resistant gonorrhea is spreading in North America is troubling but the problem is likely far more severe in the developing world, where access to treatment is more difficult and antibiotic resistance is a larger problem.
Neisseria gonorrhoeae is a bacterium that has been around since medieval times. The principal symptom is uncomfortable discharge from the penis or vagina but infection can also cause blindness in babies born of infected mothers, infertility and a severe form of arthritis.
With the advent of penicillin in the 1940s, gonorrhea became little more than a nuisance infection and it virtually disappeared after the push for safer sex related to the AIDS epidemic.
But the bacterium mutates quickly and has developed resistance to generations of new antibiotics.
"This is an extreme example of the antibiotics resistance story – one where we're running out of treatments quickly," Allen said.
She said there are several possible strategies for countering the problem of resistance to cefixime. One is to use ceftriaxome, an injectable treatment, or to use combinations of drugs for treatment.
Another is to rethink the traditional approach of treating everyone suspected of having gonorrhea with the pill before test results, and instead wait for confirmation of the infection then use molecular typing to determine which drug(s) will work for them.
There has been a resurgence of cases in recent years.
There were 11,178 cases of gonorrhea reported in Canada in 2009, up from 5,381 in 1999. More than 70 per cent of cases occur in young people aged 15 to 29 and the increase has been most dramatic among men who have sex with men.
"Condoms can prevent transmission but condoms are not commonly used for oral sex. We believe that's the principal route of transmission for gonorrhea," Allen said.