Health experts in England are increasingly getting worried that gonorrhea infections are becoming untreatable after new cases of the sexually transmitted disease rose by more than 25 percent last year.
There have been instances in Japan and Europe of infections that resist first-choice therapies.
The Health Protection Agency insisted that the threat of gonorrhoea was 'very concerning'.
It said that there was a 2 percent overall increase in the number of new sexually transmitted infections diagnosed in 2011.
Gonorrhoea is caused by bacteria and can result in infertility. Although it is treated by antibiotics, some are failing.
"We are very concerned. It is a global problem," the BBC quoted the head of sexually transmitted infection surveillance at the HPA, Dr Gwenda Hughes, as saying.
"The gonorrhoea bacterium] is very successful at developing resistance to every treatment used in the past few decades.
"We are worried that in the next five years, or some point in the future, that this is going to be a very difficult infection to treat."
Even the most resistant forms of the disease are still not untreatable.
Professor Cathy Ison, a gonorrhoea expert at the HPA, asserted that in the past, when resistance emerged, a new drug would be used.
However, she cautioned: "We don't have a new drug."
Between 2009 and 2010, the number of new sexually transmitted infections being diagnosed declined for the first time in more than a decade.
However, cases have since increased, with almost 427,000 new infections diagnosed in 2011.
More accurate tests and more people being tested elucidate some of the rise.
But the HPA said it was concerned about "ongoing, unsafe sexual behaviour" in at-risk groups.
Dr Hughes said two groups - young adults and men who have sex with men - were of especial concern.
There was a 4 percent drop in the number of diagnoses of chlamydia in young adults. However, this has been attributed to fewer people getting screened.
Sexually active people under 25 are recommended to be checked annually or when they have a change of sexual partner. Yet the number of tests fell from 2.3 million to 2.1 million between 2010 and 2011.
The government insisted that not many people were not taking care of their sexual health.
"Sexually transmitted infections can lead to infertility and other serious health problems. The message is clear: whatever your age, you should always use a condom," a Department of Health spokesperson said.
"These figures must act as a wake-up call, not only to sexually active people but also to the government and public-health services," Lisa Power, from sexual-health charity the Terrence Higgins Trust, said.
"They represent a step backwards for the nation's sexual health. The emergence of drug-resistant strains of gonorrhoea is just one consequence of continued high rates," Power added.