Medical experts have warned that a little known sexually transmitted infection could become the next superbug unless people become more vigilant.
Mycoplasma genitalium (MG) often has no symptoms but can cause pelvic inflammatory disease, which can leave some women infertile.
MG can be missed – and if it is not treated correctly, it can develop resistance to antibiotics.
The British Association of Sexual Health and HIV is launching new advice.
Mycoplasma genitalium is a bacterium that can cause inflammation of the urethra in men, causing discharge from the penis and making it painful to urinate.
In women, it can cause inflammation of the reproductive organs (womb and fallopian tubes) too, causing pain and possibly a fever and some bleeding.
You can get it by having unprotected sex with someone who has it. Condoms can prevent this spread.
It was first identified in the UK in the 1980s and is thought to affect 1-2% of the general population.
MG does not always cause symptoms and will not always need treatment, but it can be missed or mistaken for a different sexually transmitted infection, such as Chlamydia.
Tests for MG have recently been developed but are not available in all clinics yet.
It can be treated with antibiotics – but the infection is developing resistance to some of these drugs.
Eradication rates of MG following treatment with one family of antibiotics, called macrolides, are decreasing globally. Macrolide resistance in the UK is estimated at about 40%, say the guidelines.
One particular macrolide antibiotic, azithromycin, still works in most cases however.
Dr Peter Greenhouse, a sexual consultant in Bristol and BASHH member, urged people to take precautions.
“It’s about time the public learned about Mycoplasma genitalium,” he said.
“It’s yet another good reason to pack the condoms for the summer holidays – and actually use them.”