The small, pathogenic bacterium is called mycoplasma genitalium (or MG for short) and it infects the urethra, cervix and anus. Symptoms in women include pain during urination and sex, but Professor Suzanne Garland from Melbourne's Royal Women's Hospital told the ABC that there are often no obvious signs of the STI.
Particularly scary considering that it has been linked to pelvic inflammatory disease, which can cause infertility and premature birth in pregnant women when left untreated.
"In sexual health clinics, 10-35 per cent of the people being tested have it," Professor Garland said.
However, their biggest concern about MG is that it is becoming resistant to antibiotics.
“It's essentially acting like a superbug, with research showing at least 50 per cent of people have a drug-resistant MG, limiting their treatment options," Professor Garland said.
Up until recently only a small number of GPs have had access to MG testing but fortunately, there is now a simple test, covered by Medicare, to screen people for it and determine a course of treatment that is likely to work.
A timely reminder that if it's not on, it's not on.