A highly drug-resistant strain of gonorrhoea which spread rapidly throughout the north of England earlier this year could signal the disease will become "untreatable" in the near future.
England's chief medical officer Dame Sally Davies has reportedly told doctors that the strain first found in Leeds, and which spread to Macclesfield, Oldham and Scunthorpe, shows the proper prescription of treatment is essential.
35,000 cases of gonorrhoea are diagnosed in the UK each year
At least 16 cases were detected in northern England this year, including 12 in Leeds where the mutated strand was first recorded, Public Health England (PHE) said in September.
The strain, which is resistant to first-line antibiotic azithromycin, was first reported in Leeds in March but spread.
In her letter, the BBC reported that the chief medical officer said: "Gonorrhoea is at risk of becoming an untreatable disease due to the continuing emergence of antimicrobial resistance."
Alongside chief pharmaceutical officer Dr Keith Ridge, Dame Sally added: "Gonorrhoea has rapidly acquired resistance to new antibiotics, leaving few alternatives to the current recommendations.
"It is therefore extremely important that suboptimal treatment does not occur."
There were almost 35,000 cases of gonorrhoea reported in England last year and it is the second most common bacterial sexually transmitted infection in the UK after chlamydia, with the majority of cases affecting people under the age of 25.
Dame Sally has written to GPs to recommend swift treatment of all cases
Infected patients may experience discharge or pain while urinating, but around 10% of men and almost half of women do not suffer any symptoms.
If untreated, gonorrhoea can result in severe complications and lead to infertility or septicaemia in rare cases, Press Association reported.
Concerns have been growing over ''untreatable'' strains of gonorrhoea, and in 2012, the European Centre for Disease Prevention and Control warned that drug-resistant forms of the STI were spreading across Europe.