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Mycoplasma genitalium (or Mgen) is a sexually transmitted bacterial infection that’s often overlooked — but becoming increasingly important. It’s caused by a tiny, slow-growing bacterium that infects the genital and urinary tracts.
Mgen spreads through vaginal and anal sex, and possibly through oral-genital contact. Most people don’t realize they have it because symptoms are often mild or nonexistent.
What makes Mgen unique is how hard it is to detect — and how resistant it’s becoming to common antibiotics. Treatment isn’t as straightforward as it is for gonorrhea or chlamydia.
Is Mgen a real STI?
Yes. Mycoplasma genitalium is officially classified as a sexually transmitted infection. It’s been linked to urethritis in men and cervicitis and pelvic inflammatory disease (PID) in women.
How common is it?
Estimates vary, but studies suggest that around 1–2% of adults in the U.S. carry Mgen — and many don’t know it. It’s more common than gonorrhea in some groups.
What Are Symptoms of Mycoplasma Genitalium?
Most people with Mgen don’t have symptoms. When symptoms do occur, they often resemble other infections like chlamydia, gonorrhea, or a UTI.
In people with female biology:
- Unusual vaginal discharge
- Painful urination
- Pelvic pain or pain during sex
- Bleeding after sex or between periods
In people with male biology:
- Discharge from the penis (often clear or white)
- Burning or discomfort when peeing
- Itching or irritation in the urethra
In anyone:
- Rectal infections may cause discharge, bleeding, or discomfort — or no symptoms at all
- Throat infections are rare and usually asymptomatic
How long can you have Mgen without knowing?
You can carry Mgen for weeks, months, or even years without symptoms. That’s one reason it spreads silently — and why it’s often missed or misdiagnosed.
What Does Mycoplasma Genitalium Look Like?
There’s no visible way to recognize Mgen. It doesn’t cause sores or bumps — and symptoms, if they appear at all, tend to overlap with other STIs.
In people with vaginas, the main clues may be abnormal discharge, bleeding after sex, or persistent pelvic discomfort. In people with penises, it can look like a mild urethritis (inflammation of the urinary tract).
Because it mimics other conditions — like BV, chlamydia, or a UTI — you can’t know for sure unless you get tested.
How Is Mycoplasma Genitalium Transmitted?
Mgen spreads through unprotected vaginal or anal sex. Oral transmission is possible but considered rare.
You can get Mgen from:
- Vaginal sex (most common)
- Anal sex
- Possibly oral sex (rare)
- Sharing sex toys without cleaning or protection
Mgen isn’t transmitted through casual contact like hugging, kissing, toilet seats, or sharing food.
How to lower your risk:
- Use condoms during vaginal and anal sex
- Avoid sex if you or your partner have unexplained symptoms
- Get tested if you’ve had a new or multiple partners
- Don’t share unwashed sex toys
How Do You Test for Mycoplasma Genitalium?
Mgen testing is not included in standard STI panels — and that’s a big reason it goes undiagnosed.
How is Mgen diagnosed?
- NAAT (nucleic acid amplification test) is the most accurate method
- For people with vaginas: vaginal swab or urine sample
- For people with penises: first-catch urine sample
- Rectal or throat swabs may be used based on sexual practices
Who should get tested?
- People with persistent or unexplained genital symptoms
- Those who’ve tested negative for chlamydia or gonorrhea but still have symptoms
- People with recurring urethritis, cervicitis, or PID
- Partners of people diagnosed with Mgen
Are there home tests for Mgen?
Yes, but they’re not as widely available. Some labs and services include Mgen in advanced panels — always check what’s included.
How Is Mycoplasma Genitalium Treated?
Treating Mgen isn’t as simple as other STIs. The bacteria mutates easily and is increasingly resistant to antibiotics — especially azithromycin.
Current treatment guidelines (as of 2024):
- A course of doxycycline for 7 days (to reduce bacterial load)
- Followed by moxifloxacin for 7–10 days (to eliminate the infection)
Some cases require alternative regimens if resistance is confirmed.
What if it doesn’t go away?
If symptoms persist after treatment, your provider may do resistance testing or try a second-line medication. Do not re-treat without clinical guidance.
Can Mgen come back?
Yes. Reinfection is common — especially if partners aren’t treated at the same time. Follow-up testing is sometimes recommended 3–4 weeks after treatment.
Complications of Mycoplasma Genitalium
Left untreated, Mgen can cause serious complications — especially in people with vaginas:
- Pelvic inflammatory disease (PID)
- Infertility
- Chronic pelvic pain
- Increased HIV risk
- Pregnancy complications (miscarriage, preterm birth)
In people with penises, it may cause urethritis or — rarely — prostatitis or epididymitis.
Outlook & Prognosis
Mgen is treatable — but not always easy to cure. The outlook depends on early diagnosis, antibiotic resistance, and whether all partners are treated.
There’s no long-term immunity after treatment. You can get it again.
If you’re treated and symptoms persist, don’t guess or self-treat. See a provider who can evaluate for resistance.
Living With Mycoplasma Genitalium
Getting diagnosed with Mgen can feel confusing. You’ve likely never heard of it, and your doctor may not mention it unless you ask.
But it’s real, it’s common, and you’re not alone.
Living with Mgen means:
- Following through on treatment, even if it takes more than one try
- Making sure your partner(s) get tested and treated
- Asking your provider about retesting if symptoms don’t go away
The stigma around rare STIs can make this harder than it should be. But being informed — and proactive — is the best way to take control.
How to Tell Your Partner(s) You Have Mycoplasma Genitalium
This conversation might feel awkward, especially if they’ve never heard of Mgen. But being direct can help protect both of you.
You might say:
“I found out I have something called Mycoplasma genitalium. It’s a bacterial infection that spreads through sex. I’m getting treated and wanted to let you know so you can get tested too.”
Let them know:
- It’s a real STI, even if it’s not well-known
- It doesn’t always cause symptoms
- It’s important that both of you get treated — or you could pass it back and forth
Being upfront shows care and respect. And it gives you both the chance to move forward with trust.
Last reviewed: May 2025
This content is regularly reviewed and updated to reflect the latest medical guidelines.
- Caused by: Bacteria (Mycoplasma genitalium)
- Spread through: Vaginal or anal sex; possibly oral sex; shared sex toys
- Symptoms: Often none; may include discharge, burning, pelvic pain, or bleeding after sex
- Testing: NAAT (nucleic acid amplification test); urine or swab samples
- Treatment: Multi-step antibiotic regimen (e.g., doxycycline + moxifloxacin)
- Risk if untreated: PID, infertility, chronic pain, pregnancy complications
- How common: 1–2% of U.S. adults; underdiagnosed and increasing