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Medically Reviewed by:

Dr Danae Maragouthakis

Whilst advancements in medicine have proven successful in the prevention and treatment of many well known sexually transmitted infections (STIs), some relatively new and less common infections have begun to arise.

Enter Mycoplasma Genitalium (MG)! MG has been around since the 1980s, but it wasn’t until 2015 that the Center for Disease Control and Prevention (CDC) classed it as a cause for concern. Whilst it’s not as widely recognized as gonorrhoea or syphilis, MG portrays symptoms of the better known STI – chlamydia.

However, unlike chlamydia, there are only limited treatments available for MG. We’re here to shine some light on this emerging STI by breaking down what you need to know about Mycoplasma Genitalium, including how it’s transmitted, how it’s treated, and how you can get tested to prevent lasting complications.

What is Mycoplasma Genitalium (MG)?

Mycoplasma Genitalium is a sexually transmitted infection that can affect both men and women. It is transmitted by the exchange of bodily fluids during sexual intercourse. MG is just one strain of a group of bacteria known as Mycoplasma. There are over 100 different strains of Mycoplasma, characterised by their lack of cell wall and unusually small cell size.

Although relatively unknown due to limited data, studies show that up to 2% of the UK population have or have had MG, making it nearly as common as chlamydia. The large number of cases is partly due to the fact that MG - like many other STIs -  can stay in the body for long periods of time before causing any symptoms (incubation period), at which point the infection may have already been passed on to other individuals.

Mycoplasma Genitalium And Bacterial Resistance

Mycoplasma Genitalium recently gained widespread attention due to its increasing antibiotic resistance (the ability of the bacteria to resist the effects of antibiotics, meaning that the infections cannot be successfully treated with antibiotics). This emerging trend is especially troublesome in Asia, where resistance rates have been shown to exceed 90%. The spread of antibiotic-resistant MG since 2008 has occurred relatively quickly in comparison to other antibiotic-resistant STIs, such as Neisseria gonorrhoeae, thus prompting a change in UK treatment guidelines.

How is Mycoplasma Genitalium contracted?

Mycoplasma Genitalium can spread through penetrative vaginal or anal sex with an infected individual, even if they do not have any symptoms. Studies suggest that although it can sometimes occur, transmission of MG through oral sex is highly unlikely. However, you should always practice safe oral sex, as many STIs can still be transmitted by oral-to-genital contact.

As with most STIs, MG is more likely to infect people who do not use barrier methods during sex. According to one study, the factors increasing your risk of contracting MG are:

  • Having unprotected sex
  • Having sex with an infected partner
  • As a co-infection with another STI
  • Having multiple sexual partners
  • Smoking

Symptoms and Complications of Mycoplasma Genitalium

Much like many STIs, Mycoplasma Genitalium is usually asymptomatic. However, even if you are asymptomatic you can still spread the infection to others. More research is needed to accurately determine the exact incubation period for MG, but it is thought to range between 2 weeks and 3 months.

According to a number of studies, the most common symptoms of MG are:

If you or your partner display any of the above symptoms, we recommend you get tested as soon as possible and contact your nearest GUM clinic or GP for advice.

Complications in men

When left untreated, Mycoplasma Genitalium can develop into more complex infections. Men with untreated  MG may develop the following conditions:

Complications in women

Although more research is needed to determine the long-term implications of MG in women, studies published in the Journal of Microbiology suggest that women are more likely to develop the following complications when MG is left untreated:

  • Cervicitis (irritation or infection of the cervix)
  • Pelvic inflammatory disease (PID (an infection of the female reproductive organs that can result in pain, discharge, and fever)
  • Pregnancy complications (more is research is needed to confirm the correlation, but evidence suggests that prolonged infection with MG can cause preterm delivery, spontaneous abortion, and/or infertility)

Treatment of Mycoplasma Genitalium

Mycoplasma Genitalium is a bacteria, meaning that it can be treated successfully using a course of antibiotics (like tetracyclines and fluoroquinolones). However owing to the nature of the organism and its lack of a cell wall, certain antibiotics that normally act on the bacterial cell wall (like penicillins and cephalosporins), will be unable to elicit an effect.

That said, the CDC recommends a two-stage therapy approach to treatment. This helps to 1) reduce the rate of antimicrobial resistance of the bacteria, and 2) treat it effectively. The recommended treatment for Mycoplasma Genitalium is: 

  • If the bacteria is macrolide sensitive (can be destroyed by the use of a macrolide antibiotic): doxycycline followed by azithromycin
  • If the bacteria is macrolide-resistant (cannot be destroyed by the use of a macrolide antibiotic): doxycycline followed by moxifloxacin

A test for cure is not normally recommended for those who are asymptomatic. However, if someone has persistent symptoms following treatment, and a test for MG is available, then a  repeat test would be recommended along with any additional treatment (if required). 

How can we stop the spread of MG?

Staying up to date about new STIs and those developing bacterial resistance can help protect you and your partner(s). Given that Mycoplasma Genitalium has only recently emerged as a growing concern, many people may have never been tested for it, and thus many have unknowingly spread it to others.

So, what should you do? The CDC recommends you should get tested frequently—every 3-6 months or after every new sexual partner. The earlier you diagnose an STI, the sooner you can start treatment to prevent or reduce your risk of developing further complications! 

Why not try our window period calculator to help guide you on when to get tested?


Hassan Thwaini is a qualified Clinical Pharmacist who has completed his Master's degree at the University of Sunderland. Since then he has not only pursued community and clinical pharmacy, but has expanded to aid in humanitarian work across the less fortunate areas of the globe. Hassan is currently working as a medical writer and has successfully been published within various nutritional websites, produced unique content for his university board, and carried out research for renowned surgeons.



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