Mycoplasma Genitalium (MGen) and Sexual Health: UK Diagnosis and Treatment

Mycoplasma Genitalium, commonly known as MGen, is a bacterium that was first identified in the early 1980s. While it is less widely known than Chlamydia or Gonorrhoea, it is a significant cause of sexually transmitted infections (STIs) in the United Kingdom. MGen specialises in attaching to the cells of the urogenital tract, leading to inflammation and discomfort.

According to NICE (National Institute for Health and Care Excellence) and BASHH (British Association for Sexual Health and HIV) guidelines, MGen is a common cause of Non-Gonococcal Urethritis (NGU) in men and Pelvic Inflammatory Disease (PID) in women. Despite its prevalence, it was not routinely tested for in the UK until relatively recently, meaning many cases went undiagnosed or were incorrectly treated as other STIs.

Like many other STIs, MGen is frequently asymptomatic, meaning many people carry and spread the bacteria without knowing. However, when symptoms do occur, they can be distressing.

Symptoms in Men

• Urethral discharge: A watery or pus-like discharge from the penis.
• Dysuria: A stinging or burning sensation when passing urine.
• Urethritis: Inflammation and irritation at the tip of the penis.

Symptoms in Women

• Vaginal discharge: An unusual change in the consistency or smell of discharge.
• Intermenstrual bleeding: Spotting or bleeding between periods or after sex.
• Pelvic pain: Persistent discomfort in the lower abdomen.
• Dyspareunia: Pain during sexual intercourse.

Diagnosis of MGen relies on a Nucleic Acid Amplification Test (NAAT). Standard laboratory cultures do not work for MGen because the bacteria grow extremely slowly. In a UK clinical setting, the following methods are used:

• For Men: A First Void Urine (FVU) sample, which must be the very first stream of urine passed in the morning or after not urinating for at least one hour.
• For Women: A vaginal swab (often self-taken) or a cervical swab.

Under current BASHH guidelines, if MGen is detected, the laboratory should also test for macrolide resistance. This is crucial because many strains of MGen are now resistant to azithromycin, which was previously the first-line treatment. Knowing the resistance profile allows your doctor to prescribe the most effective antibiotic immediately.

Antibiotic resistance is a major challenge in treating MGen. Because the bacteria lack a cell wall (unlike most other bacteria), common antibiotics like penicillin are completely ineffective. The medical community has seen a rise in 1-stage and 2-stage mutations that make the bacteria resistant to standard treatments.

If you have been treated for suspected Chlamydia but your symptoms persist, it may be because MGen was the actual culprit. This is why targeted testing is essential. Following NHS recommendations, GPs and sexual health clinics now use specific, often multi-day antibiotic regimens to ensure the infection is cleared entirely and to prevent further resistance from developing.

Speaking to an online GP in the UK is a convenient and confidential way to manage your sexual health concerns. If you are experiencing symptoms or have been notified by a partner, an online consultation can provide a pathway to testing and treatment.

An online doctor can:

• Assess your symptoms and determine if an MGen test is necessary.
• Provide a referral for private testing kits or clinic visits.
• Review your test results, including macrolide resistance data.
• Prescribe the appropriate course of antibiotics (often involving doxycycline followed by azithromycin or moxifloxacin) in line with NICE guidelines.
• Issue a sick note if your symptoms are severe enough to require time off work.

It is standard practice to avoid all sexual contact—including oral sex—until you and your partner(s) have finished the full course of treatment and a 'test of cure' has been confirmed if necessary.

Leaving MGen untreated is not recommended due to long-term health risks. In women, the infection can ascend to the uterus and fallopian tubes, causing Pelvic Inflammatory Disease (PID). PID can lead to chronic pelvic pain, ectopic pregnancy, and in some cases, infertility. In men, MGen has been linked to epididymitis (inflammation of the tubes behind the testicles), though the evidence for its impact on male fertility is still being researched. Both genders are at a higher risk of contracting other STIs, such as HIV, if MGen has already caused inflammation in the genital tract.