Mgen Symptoms in Women: Discharge, Bleeding & Pain

Mycoplasma genitalium (Mgen) in women most often causes cervicitis, inflammation of the cervix, which shows up as abnormal vaginal discharge, bleeding after sex, spotting between periods, and pelvic pain or pain during urination. But many women have no symptoms at all, which lets the infection persist and sometimes climb into the upper reproductive tract.

What Mycoplasma genitalium is and how common it is

Mycoplasma genitalium is one of the smallest free-living bacteria known, and it has an unusual quirk: it lacks a cell wall. That single fact drives almost everything that makes it frustrating to treat, because beta-lactam antibiotics, penicillins and cephalosporins, kill bacteria by attacking the cell wall, so they do nothing here CDC STI Guidelines, 2021. Learn more about mycoplasma genitalium and how it behaves differently from other STIs.

It's an emerging, sexually transmitted cause of urethritis in men and cervicitis in women, spread through vaginal, anal, and likely oral contact. It's not rare. Estimated general-population prevalence is around 1.3% in higher-development countries and closer to 3.9% in lower-development settings prevalence review, which puts it in the same ballpark as more familiar infections. In men, it accounts for a meaningful share of urethritis cases; in women, it raises the risk of cervicitis and its complications CDC EID, 2022.

Symptoms of Mgen in women

When Mgen does cause symptoms in women, they come from the cervix being inflamed and irritated. The signs overlap heavily with chlamydia and gonorrhea, which is exactly why a clinician can't tell them apart by looking, testing settles it.

Cervicitis

Cervicitis is inflammation of the cervix, the lower part of the uterus that opens into the vagina. With Mgen, the immune response to the bacteria makes the cervical tissue red, swollen, and friable, meaning it bleeds easily when touched. A clinician may see this on exam even when a woman feels nothing. Cervicitis is the hallmark female presentation of Mgen.

Abnormal discharge

Inflamed cervical glands produce more mucus, often mixed with pus, so the discharge may be heavier than usual, change color toward yellow or gray, or develop an unfamiliar odor. There's no single "Mgen discharge": it looks like the discharge of other cervical infections, so it's a reason to test, not a diagnosis on its own.

Bleeding after sex and between periods

Because the inflamed cervix is fragile, friction during intercourse can cause post-coital bleeding, light spotting or pink discharge after sex. Some women also notice spotting between periods. This bleeding is one of the more specific clues to cervicitis and shouldn't be brushed off as normal, especially if it's new.

Pelvic pain and painful urination

A dull ache or pressure low in the pelvis can develop, sometimes with pain during sex (dyspareunia) or a burning feeling when urinating (dysuria) if the urethra is involved. Worsening or one-sided pelvic pain, fever, or pain deep with intercourse can signal the infection has spread upward and warrants prompt care.

Often, no symptoms at all

This is the part worth sitting with: Mgen is frequently silent, and that's particularly true in women. A woman can carry it for months with nothing to feel, while it quietly drives inflammation. Silent infection is part of why it spreads and why complications sometimes appear before anyone knew there was an infection to treat.

Complications: PID, infertility risk, and pregnancy

The reason untreated Mgen matters is what happens when it ascends from the cervix into the uterus and fallopian tubes.

• Pelvic inflammatory disease (PID): infection and inflammation of the uterus, fallopian tubes, and surrounding tissue. Mgen is associated with a roughly twofold increased risk of PID. PID can cause lasting pelvic pain and scarring of the tubes.
• Infertility, scarred or blocked fallopian tubes from tubal inflammation can prevent egg and sperm from meeting. Mgen carries about a twofold higher risk of female infertility, which is why catching and treating it matters even when symptoms are mild.
• Preterm delivery: in pregnancy, Mgen is linked to a higher risk of delivering early, before the lungs and other organs are fully ready.

Why Mgen is hard to treat: macrolide resistance

For years, a single dose of azithromycin cleared Mgen. That era is ending. The bacteria readily acquire mutations in their 23S rRNA, at base positions 2058 and 2059, that make azithromycin and other macrolides stop working macrolide-resistance study. These resistance markers correlate closely with treatment failure, and in the United States, Canada, Western Europe, and Australia they're now found in 44% to 90% of infections, exceeding 50% in many areas and topping 62% in one US STI clinic.

Worse, hitting a susceptible strain with a single 1-g azithromycin dose actually breeds resistance in roughly 10% to 12% of cases, the drug knocks back the weak bacteria and leaves resistant ones to flourish. That's the central reason single-dose azithromycin is no longer recommended. The full picture, including newer fluoroquinolone resistance, is covered in our guide to mgen cure.

How Mgen is diagnosed

Mgen is not on the standard STD panel. Most chlamydia/gonorrhea tests won't detect it, so it's commonly missed unless someone specifically orders the right test, typically after symptoms persist or recur. Diagnosis uses a nucleic acid amplification test (NAAT) designed for this organism; the Aptima Mycoplasma genitalium assay was FDA-approved in 2019 and is the only NAAT cleared for it in the US AAFP, 2021.

In practice, testing is simple. It's usually a self-collected vaginal swab, a urine sample, or a quick clinic exam, with results back in a few days. Many health departments, Planned Parenthood, and Title X clinics offer it free or low-cost. Because Mgen needs a dedicated test, ask for it by name if you have ongoing symptoms. See get tested to start, and if you're timing things around an exposure, check when to test after exposure. Note that routine screening of people without symptoms isn't recommended.

Resistance-guided treatment

Treatment now follows a two-step, resistance-guided approach rather than a one-and-done pill. Doxycycline goes first: on its own it only clears Mgen about 30% to 40% of the time, but it sharply lowers the bacterial load and sets up the second drug to succeed CDC Mgen Guidelines, 2021. The second drug depends on whether the strain is macrolide-susceptible or resistant, which is why the molecular resistance result on the NAAT is so useful.

This approach works. In a resistance-guided therapy trial, doxycycline-then-azithromycin cured 95.4% of susceptible infections and doxycycline-then-moxifloxacin cured 92.0%, with new macrolide resistance emerging in only 4.6% Read et al., 2019. Real-world rollout in Australia pushed cure rates above 90% even where quinolone resistance ran 15% to 20% Australian implementation. The catch is that fluoroquinolone resistance is rising too, pretreatment parC and gyrA mutations were found in an Asia-Pacific cohort, with combined macrolide and fluoroquinolone resistance in 8.6% of specimens CDC EID, 2017, and the first moxifloxacin failures traced to a specific parC mutation called S83I NYSDOH/Hopkins guideline. Don't forget partners: a current partner needs evaluation and the same regimen, or you'll pass it back. See mgen partner treatment for how that works.

When to see a clinician

Get checked if you notice new or unexplained vaginal discharge, bleeding after sex or between periods, pelvic pain, or burning with urination: especially if a previous STI treatment didn't resolve your symptoms, which is a classic flag for Mgen. A diagnosis here is common and treatable; clinics handle it daily, and it says nothing about you as a person. Seek same-day care for worsening pelvic pain, fever, or pain deep with intercourse, which can point to PID.

Keep exploring on EasySTD: what STD testing costs, your risk of an STD and Mycoplasma genitalium testing.