Mycoplasma Genitalium (MGen): Symptoms, Testing, and Treatment in the UK

Mycoplasma genitalium, frequently referred to as MGen, is a bacterium that can be passed on through unprotected vaginal or anal sex. While it was only discovered in the 1980s, it is now recognised as a significant cause of urinary and sexual health issues in the UK. In many cases, it behaves similarly to Chlamydia but requires different medical management due to its unique structure—it lacks a cell wall, which makes many common antibiotics, like penicillin, completely ineffective.

According to the British Association for Sexual Health and HIV (BASHH), MGen is a major contributor to inflammation of the urethra (urethritis) in men and inflammation of the cervix or pelvic organs in women. Because it is often asymptomatic, many people unknowingly carry the infection for months or even years.

Many individuals with Mycoplasma genitalium do not experience any symptoms. However, when symptoms do occur, they can be distressing and are often mistaken for other STIs. In the UK, MGen is frequently suspected when a patient has symptoms that persist even after being treated for Chlamydia.

Symptoms in Men

• Penile discharge: A watery or mucoid discharge from the tip of the penis.
• Dysuria: A painful or stinging sensation when passing urine.
• Urethral irritation: Itching or discomfort inside the penis.

Symptoms in Women

• Vaginal discharge: An unusual change in discharge.
• Pelvic pain: Discomfort in the lower abdomen or durante intercourse (dyspareunia).
• Intermenstrual bleeding: Bleeding between periods or after sex.

One of the biggest challenges with MGen in the UK is that it is not typically part of a "standard" STI screen at every GP surgery or sexual health clinic. Routine tests usually focus on Chlamydia, Gonorrhoea, Syphilis, and HIV. If you have persistent symptoms but your tests for these common infections have come back negative, MGen is a likely culprit.

Diagnosis requires a specific Nucleic Acid Amplification Test (NAAT). For men, this usually involves a first-void urine sample (the very first part of the stream). For women, a vaginal swab is preferred as it is more sensitive than a urine test. Because MGen is slow-growing and difficult to culture, these high-tech molecular tests are the only reliable way to confirm an infection.

Treatment for MGen is more complex than for many other STIs. In recent years, Public Health England and NICE have noted a significant rise in antibiotic resistance. The bacteria have become increasingly resistant to azithromycin, which was once the first-line treatment. Following the current BASHH guidelines, UK doctors now often prescribe a multi-stage antibiotic course.

The treatment usually begins with a week of doxycycline to reduce the bacterial load, followed immediately by a more potent antibiotic such as moxifloxacin. It is vital to complete the entire course exactly as prescribed, even if symptoms vanish early, to prevent the bacteria from developing further resistance. You must also avoid any sexual contact—including oral sex—until you and any partners have finished treatment and, in some cases, received a 'test of cure' several weeks later.

If you are experiencing symptoms of an STI or have been informed by a partner that they have tested positive for MGen, seeking medical advice is essential. Many patients find the convenience of an online doctor in the UK helpful for discussing confidential sexual health concerns without the wait for an in-person appointment.

An online GP consultation can help you:

• Discuss persistent symptoms that Haven't cleared up with standard treatments.
• Understand your test results and the implications of an MGen diagnosis.
• Receive a referral or advice on where to obtain specialist MGen testing.
• Discuss the appropriate antibiotic protocols aligned with UK national guidelines.
• Get advice on partner notification and future prevention.

While MGen is a specialist area of sexual health, an online GP serves as an excellent first point of contact to ensure you are on the right pathway for diagnosis and recovery.

Leaving MGen untreated can lead to long-term health complications. In women, the infection can spread to the reproductive organs, causing Pelvic Inflammatory Disease (PID). PID can lead to chronic pelvic pain and, in severe cases, increases the risk of ectopic pregnancy or infertility. In men, although complications are rarer, it can lead to acute epididymitis (inflammation of the testicles).

Furthermore, having an active MGen infection can make it easier to contract or transmit other STIs, including HIV, because the inflammation compromises the natural protective barriers of the genital tract.