You probably haven't heard of mycoplasma genitalium, or MG and, until recently, very few clinics, even sexual health specialists, could test for it.

Researchers say it carries many of the same health risks as chlamydia and studies have estimated it has a prevalence of 1 to 3 per cent of the population in high income countries, including Australia.

Testing has been limited to research laboratories but that looks set to change in Australia, which recently became one of the first countries to approve commercial tests for MG.

The Australian creator and sponsor of one of the tests, NSW-based SpeeDx, which received approval from the Therapeutic Goods Administration in January - hopes it will be included in routine sexual health screening in the future.

MG was first discovered in the early 1980s but is still listed as "recently identified" in the Australian STI management guidelines for use in primary care and considered an "emerging issue" by the US Centers for Disease Control.

"Many doctors don't really know about it, most doctors aren't testing for it, it's extraordinarily unrecognised," said Catriona Bradshaw, a sexual heath academic at Monash University and senior clinician at The Alfred hospital's Melbourne Sexual Health Centre.

"It has all of the same clinical consequences that chlamydia does.

"It has taken a lot longer to recognise its role in disease, particularly in women, and it's taken a lot longer to accumulate the evidence that it does cause these diseases."

It has been found to cause pelvic inflammatory disease, which involves pain, discharge and bleeding after sex in women; and urethritis in men, which involves pain and burning when urinating, Associate Professor Bradshaw said.

There is still debate within the scientific community about early research that has also linked MG to spontaneous miscarriage, infertility and premature birth.

Like chlamydia, most infected people won't have any symptoms, and it's this lack of awareness and testing that Associate Professor Bradshaw believes has helped fuel the infection's incredible resistance to drugs.

"This resistance to frontline therapy has occurred over the last decade, has largely gone unnoticed because of the lack of availability of testing and the lack of surveillance," she said.

"Now approximately 50 per cent of infections are resistant to frontline therapy.

"Our second line treatment, which was 100 per cent effective in 2006, is also now failing in 12 to 15 per cent of cases."

The Australian test screens for MG but also for drug resistance.  Associate Professor Bradshaw said widespread testing would reduce the use of antibiotics that don't stand a chance against the half of infections already resistant to drugs.

A study on drug resistant gonorrhea and MG recently published in the Nature Reviews Urology journal called for urgent "enhanced local, national and international surveillance" of resistant bacteria and research into new treatments.

Professor Basil Donovan, a sexual health expert from the Kirby Institute, said the speed with which MG had become drug resistant was "unusual in terms of any infection".

"It's got this incredible propensity to develop resistance and it's not just the first line antibiotics it's the second and third line antibiotics as well," he said.

Professor Donovan said little was known about MG because the STI field was already overcrowded and there were still questions over the severity of its implications for those infected.

"It's walked into a crowded room and we're not entirely sure of just how nasty it is," he said.