Mycoplasma Genitalium — The STI Koh Samui Clinics Often Do Not Test For

Clinically reviewed by Dr. Ponlawat Pitsuwan, Physician, Doctor Samui. Last reviewed: September 2026

You got tested after unprotected sex. The results came back negative for chlamydia and gonorrhoea, but something still feels wrong. The burning when you urinate has not gone away. Or you were given antibiotics for suspected chlamydia at a pharmacy near Chaweng, finished the course, and the symptoms are still there two weeks later.

This is one of the most common situations we see at our Chaweng clinic, and Mgen is behind it more often than people expect. It is a sexually transmitted infection that most standard STI tests in Thailand simply do not check for. Chlamydia, gonorrhoea, HIV, syphilis: those are the four on the usual panel. Mgen is not on that list unless you ask for it specifically. That gap is why people stay symptomatic, keep receiving antibiotics that do not work, and sometimes develop complications that take months to resolve.

What Mycoplasma Genitalium Actually Is

Mgen is a bacterium that infects the urinary and reproductive tract. It spreads through unprotected vaginal or anal sex. Reliable testing has only become widely available in recent years, which is one reason many clinics still leave it off their routine screens.

A large proportion of people who carry Mgen have no symptoms at all. That makes it easy to miss and easy to pass on without knowing. When symptoms do appear, they look almost identical to chlamydia or a UTI, which is exactly where the confusion starts.

Symptoms That Are Easily Mistaken for Chlamydia or a UTI

In men, the most common signs are a burning or stinging sensation when urinating, a clear or white discharge from the penis, and discomfort in the urethra that can last for weeks. Some men develop epididymo-orchitis, which is swelling and pain in the testicles, if the infection is not treated. This is less common but does happen, and it is a reason not to wait.

In women, symptoms include unusual vaginal discharge, pelvic pain, pain during sex, and bleeding between periods or after sex. These are the same symptoms that prompt a diagnosis of cervicitis (inflammation of the cervix) or pelvic inflammatory disease (PID). Many women are treated for those conditions without anyone testing for Mgen as the underlying cause.

If your symptoms fit either picture and your chlamydia result came back negative, or you were treated for chlamydia and did not improve, Mgen deserves a proper test.

Does a Standard STD Test on Koh Samui Include Mycoplasma Genitalium?

No. Most standard STI panels at walk-in clinics and pharmacies across Koh Samui test for chlamydia, gonorrhoea, HIV, and syphilis only. Mgen requires a PCR test that detects the bacteria’s genetic material. This test has to be requested by name.

Some clinics list Mgen in a premium package with no explanation of why it matters. Others do not offer it at all. Our sexual health screening at Doctor Samui includes Mgen as a named option, available at our Chaweng walk-in clinic or during a hotel or villa visit anywhere on the island.

If you are booking an STI screen anywhere on Koh Samui, ask directly: "Does this test include a PCR for Mycoplasma genitalium?" If the answer is unclear, it probably does not.

Testing: When to Test and What to Expect

The window period for Mgen is roughly one to two weeks after exposure. Testing before that point can give a false negative even if the infection is present. If you had unprotected sex less than two weeks ago and you are already symptomatic, come in for an assessment. We can review your situation clinically while waiting for the right window to pass.

The test itself is simple. For men, we use a first-catch urine sample. For women, a vaginal swab, either self-collected or taken during examination. Results usually come back within a few days. We screen for co-infections at the same time, because chlamydia, gonorrhoea, and ureaplasma can all produce the same symptoms, and having more than one infection at once is not unusual.

Why the Right Antibiotic Matters for Mycoplasma Genitalium

This is where most online advice gets it wrong, and it matters particularly on Koh Samui where antibiotic courses from pharmacies are common.

Azithromycin used to be the standard treatment for Mgen. It is also the antibiotic most often given for suspected chlamydia or urethritis. The problem is that azithromycin resistance in Mgen is now documented in a significant and growing proportion of cases across Southeast Asia. Using azithromycin on a resistant strain does not clear the infection, and it may make follow-up treatment harder.

Current guidance follows a stepped approach. A short course of doxycycline comes first to reduce the bacterial load. This is followed by azithromycin or, if resistance is likely, moxifloxacin. The choice of antibiotic should be guided by your clinical history, not a pharmacy shelf. This is not a condition to self-treat.

What Happens If Mycoplasma Genitalium Is Left Untreated

In women, untreated Mgen is a recognised cause of PID, which can lead to scarring of the fallopian tubes, infertility, ectopic pregnancy, and complications in pregnancy. The damage can happen slowly and without obvious pain, which is why early testing matters.

In men, persistent urethritis is the most common long-term problem. Epididymo-orchitis can develop and may, in some cases, affect fertility. The infection can sit quietly for months before it becomes obvious.

Because Mgen is asymptomatic in many people, complications can build before anyone thinks to test for it. A proper STI test that includes Mgen is the only reliable way to know it is there.

Getting Tested on Koh Samui: Walk-In or Hotel Visit

You do not need to fly to Bangkok or Phuket for a proper Mgen test. Doctor Samui offers sexual health testing including PCR for Mgen at our walk-in clinic in Chaweng. If you are staying in Bophut, Lamai, Maenam, Choeng Mon, or anywhere else on the island, our 24/7 hotel and villa visit service means a doctor can come to you.

Testing is discreet and confidential. Many patients, tourists and long-stay expats alike, prefer that to walking into a clinic in a busy resort area. We also talk through partner notification during the consultation, a step that matters and one that is easy to put off without support.

If you test positive, we explain the resistance picture as it applies to your case and arrange a test of cure two to four weeks after you finish antibiotics. That follow-up PCR confirms the infection has actually cleared. With Mgen resistance rates where they are, skipping it is not a good idea.