New antibiotic could stave off drug-resistant gonorrhoea

Drug-resistant gonorrhoea is on the rise worldwide, but a new antibiotic could buy us more time before the emergence of completely untreatable strains of the bacteria, which is known to potentially raise the risk of infertility.

The sexually transmitted infection is estimated to affect more than 80 million people worldwide annually. It occurs when the bacterium Neisseria gonorrhoeae infects various body parts, including the anus, urethra and genitals. Common symptoms include a burning sensation when urinating and unusual discharge from the vagina or penis. If left untreated, it can cause infertility and pregnancy loss.

The disease is usually treated with injectable ceftriaxone, the last antibiotic that works against most N. gonorrhoeae strains – but the bacterium is evolving resistance to this drug too. For instance, the World Health Organization found that, across 12 countries including Thailand, South Africa and Brazil, about 5 per cent of cases were ceftriaxone-resistant in 2024 – a sixfold increase since 2022.

If ceftriaxone fails, doctors usually turn to other antibiotics, but it’s only a matter of time until completely untreatable strains evolve. “We are running out of options,” says Alison Luckey at the Global Antibiotic Research and Development Partnership. “It’s been decades since a gonorrhoea drug has been approved.”

Attempting to stall this growing threat, researchers previously found that gepotidacin, an antibiotic pill used against urinary tract infections, can effectively treat gonorrhoea, with the US Food and Drug Administration (FDA) expected to make an approval decision on using the drug in the US today. But since bacteria usually evolve resistance to new drugs, the more treatment options we have, the better, says Luckey.

She and her colleagues have now tested another drug, zoliflodacin, which was specifically developed to treat drug-resistant gonorrhoea. The researchers randomly assigned 744 people with gonorrhoea – from the US, South Africa, Thailand, Belgium and the Netherlands – to take either zoliflodacin, or a combination treatment involving ceftriaxone and another antibiotic called azithromycin.

By swabbing participants’ cervix or urethra six days later, on average, the researchers found that zoliflodacin had cleared about 91 per cent of the infections, while the equivalent figure was 96 per cent among those who received standard treatments. This means there was no significant difference between the treatments. Side effects, such as headache and nausea, were similar and transient in both groups.

The vast majority of the 744 cases were caused by strains that weren’t resistant to ceftriaxone or azithromycin. But a prior study showed that, in a lab dish, zoliflodacin is effective against gonorrhoea strains resistant to all standard antibiotics. As such, the results add to evidence that zoliflodacin could offer a fresh approach against gonorrhoea, not just as a first-line treatment but potentially when standard drugs fail, says Luckey. “In places where you’re looking at frequent risk of resistance, there may be a greater appetite to use it sooner as a first-line treatment,” she says. What’s more, the drug – which is taken orally – could offer a more convenient way to treat gonorrhoea than ceftriaxone, which some people avoid due to a fear of needles, she says.

The researchers have already submitted their data to the FDA, which is expected to make an approval decision on 15 December, says Luckey.

If this is positive, approvals elsewhere, including in the UK, Europe and Asia, will probably follow soon after, says Charlotte-Eve Short at Imperial College London, who wasn’t involved in the study.

Together with ongoing efforts to vaccinate against gonorrhoea, with the meningitis group B vaccine recently being rolled out in the UK against gonorrhoea, gaining two new drugs could mark a turning point in the fight against drug-resistant gonorrhoea, says Short. “This is great news,” she says. “We have yet to see on a population level what this could mean, but if we’re coming at it from two different directions – we’ve got prevention and we’ve got treatment – we should be able to make a bigger impact on reducing resistance.”