Why super-gonorrhoea is spreading and may soon be untreatable

England’s public health agency has launched an “incident response” after discovering more cases of gonorrhoea that are resistant to nearly all antibiotics.

Gonorrhoea, also known as “the clap”, was largely controlled by antibiotics after the second world war. But the bacteria readily acquire genes for resisting drugs, and by 2012, the World Health Organization warned that strains of the infection were appearing that resisted nearly all classes of antibiotics.

In 2012, the UK mandated treatment with two antibiotics at once – azithromycin pills plus an injection of ceftriaxone – so if bacteria acquired resistance to one, they would be killed by the other. Gonorrhoea that resists azithromycin was detected in Japan in 2013, and in 2015 clinics in northern England reported 16 people with similarly resistant infections.

That means the infections are only killed by ceftriaxone – and if any of the bacteria acquire resistance to it, there is no backup antibiotic to kill them off – so resistance to this last treatment could develop quickly, says Mark Lawton, a doctor in Liverpool and a spokesman for the British Association for Sexual Health and HIV.

Resistance to azithromycin is emerging, Lawton says, partly because people who test positive for gonorrhoea have been buying treatments confidentially from internet pharmacies. You cannot buy a drug that must be injected, like ceftriaxone, on the internet, so people have bought the related oral drug cefixime instead. But that doesn’t penetrate rectal and other tissues that harbour the bacteria as readily as the injected drug, leaving azithromycin on its own. Any bacteria that resisted it could therefore thrive.

Otherwise new drugs are needed – but there has been little interest in developing them for gonorrhoea, an apparently defeated disease, and little is in the pipeline, says Fisman.

One option may be to increase the doses of the existing drugs, or perhaps to go back to old drugs that might work against gonorrhoea. Research has started that is aimed at finding out if a vaccine against meningitis B, caused by related bacteria, might cause some cross-immunity to gonorrhoea.