Mycoplasma genitalium (MG) presents similar symptoms to chlamydia and is more resistant to antibiotics.
It can lead to pelvic inflammatory disease and ultimately infertility in women if left untreated, doctors have warned.
For women it can cause pain or bleeding during sex and a burning sensation when urinating.
In men it causes watery discharge from the penis and painful urination.
Around one to two per cent of men and women are thought to be infected with the disease in the UK.
The British Association of Sexual Health and HIV has launched new guidelines on how to treat and diagnose the disease.
It is best treated by a seven day course of the antibiotic doxycycline, followed by a course of azithromycin.
It can also be treated by an antibiotic called macrolides, but the guidelines warned that MG is becoming increasingly resistant to it.
Although tests for MG have been developed they are not currently available at all clinics.
If a doctor wishes to test for the disease they can send samples to Public Health England's laboratory to get a diagnostic result.
A survey carried out by BASHH on 125 out of 152 public health commissioners in England revealed that only one in ten plan to provide testing for the superbug in their local areas within the next year.
As the symptoms of the disease are similar to chlamydia it can often be misdiagnosed and go untreated, doctors have claimed.
Dr Paddy Horner, consultant senior lecturer in sexual health at Bristol University and one of the authors of the new guideline told the BBC: “This is not curing the infection and is causing antimicrobial resistance in MG patients.
"If practices do not change and the tests are not used, MG has the potential to become a superbug within a decade, resistant to standard antibiotics."
The best way to prevent the disease is to practice safe sex as it is transmitted by having intercourse with someone who is already infected.
Dr Helen Fifer, consultant microbiologist at Public Health England welcomed the new guidelines on the disease.
She said: “The new BASHH guideline on MG is a positive step forward to improving testing and diagnosis.
“If you have symptoms of an STI, we recommend you get tested at your local sexual health clinic. Everyone can protect themselves from STIs by consistently and correctly using condoms with new and casual partners.”