Mycoplasma Genitalium: Symptoms, Testing & Treatment Guide

Quick Answer

Mycoplasma genitalium (M. gen) is a sexually transmitted bacterial infection that affects an estimated 3.3 million Americans. It often causes no symptoms at all, which means most people carry it without knowing. Left untreated, it can lead to urethritis in men and pelvic inflammatory disease in women. If you think you may have been exposed, ask your healthcare provider specifically for an M. gen test — standard STI panels do not include it.

What Is Mycoplasma Genitalium?

Mycoplasma genitalium is a small, slow-growing bacterium that infects the urogenital tract. It was first identified as a cause of sexually transmitted infection in 1981, but for decades it flew under the radar because it is extremely difficult to culture in a lab. Only in recent years have reliable diagnostic tests become widely available, and what we've learned has been eye-opening.

In my experience, most patients who come in with M. gen have never heard of it. They know about chlamydia and gonorrhea — but not the infection that causes up to 30% of urethritis cases in men and has been linked to serious reproductive complications in women. According to CDC-supported research, the general population prevalence of M. genitalium in the United States is approximately 1.7% among adults aged 14 to 59 — roughly 3.3 million people at any given time (Torrone et al., CDC/NHANES, 2021). Among patients visiting STI clinics, that number jumps to 16.6% (Manhart et al., MyGeniUS Study, 2023).

The CDC now lists M. genitalium on its Watch List of Antimicrobial Resistance Threats, putting it alongside drug-resistant gonorrhea as a pathogen of serious public health concern.

How Does Mycoplasma Genitalium Spread?

M. gen spreads through sexual contact — vaginal, anal, and possibly oral sex, though the evidence for oral transmission is still evolving. It is not spread through casual contact, kissing, sharing utensils, or toilet seats.

The patients I see most often with M. gen tend to fall into a few patterns: sexually active adults under 30, individuals with multiple partners, and people who do not consistently use condoms. However, any sexually active person can contract it. Key risk factors include:

• Unprotected vaginal or anal sex

• Multiple sexual partners

• A current or recent diagnosis of another STI (chlamydia coinfection is common)

• Age under 25

One thing I always tell patients: M. gen does not require "risky" behavior. A single unprotected sexual encounter with an infected partner is enough.

What Are the Symptoms?

This is what makes M. genitalium so tricky — most infections are completely asymptomatic. Research shows that roughly 9% of asymptomatic men and 15% of asymptomatic women tested at STI clinics carry the bacterium without any symptoms at all.

Symptoms in men (when present):

• Burning or pain during urination

• Watery or thin discharge from the penis

• Urethral irritation or itching

• Pain or swelling in the testicles (less common)

Symptoms in women (when present):

• Abnormal vaginal discharge

• Bleeding between periods or after sex

• Pain during intercourse

• Lower abdominal or pelvic pain

• Burning during urination

What I typically see in patients who present to our clinic is frustration: they were already treated for chlamydia or gonorrhea, but symptoms persisted. That's often the point where M. gen testing finally happens — and in my view, it should happen sooner.

How Long Can You Have Mycoplasma Genitalium Without Knowing?

This is one of the most common questions patients ask, and the honest answer is: potentially months to years. Unlike gonorrhea, which tends to produce noticeable symptoms within days, M. genitalium can persist silently in the urogenital tract for extended periods.

There is no definitive research on maximum duration, but clinical experience and published case data suggest that untreated asymptomatic infections can persist indefinitely. This is a significant concern because during all that time, the person can unknowingly transmit the infection to sexual partners.

How Is Mycoplasma Genitalium Diagnosed?

Diagnosing M. gen requires a nucleic acid amplification test (NAAT), which detects the bacterium's genetic material from a urine sample or urogenital swab. This is the same type of technology used for chlamydia and gonorrhea testing.

Here's the critical issue: most standard STI panels do not include M. genitalium. If your provider doesn't specifically order it, you won't be tested for it. The FDA cleared the first commercially available M. gen test (Hologic Aptima) in 2019, and availability has improved since then — but it is still far from routine.

Current CDC and international guidelines recommend M. gen testing in these situations:

• Urethritis symptoms that persist after treatment for chlamydia and gonorrhea

• Recurrent cervicitis in women

• Pelvic inflammatory disease

• Sexual partners of someone diagnosed with M. gen

When testing is ordered, resistance testing (specifically for macrolide resistance mutations) should ideally be included. This matters enormously for treatment decisions. If you're unsure how to bring this up with your doctor, a direct request is always appropriate.

How Is Mycoplasma Genitalium Treated?

Treatment for M. gen has become significantly more complicated in recent years due to rapidly rising antibiotic resistance. This is not a condition where a single prescription reliably fixes the problem.

Current standard of care (CDC 2021 Guidelines):

The CDC recommends a two-step sequential therapy approach. This is critical — single-drug therapy is no longer considered adequate:

Step 1: Doxycycline 100 mg twice daily for 7 days. This reduces the bacterial load but does not reliably cure the infection on its own (cure rate approximately 30–60% as monotherapy).

Step 2 (resistance-guided):

• If macrolide-sensitive: Azithromycin 1g on day 1, then 500 mg daily for 3 additional days

• If macrolide-resistant or resistance unknown: Moxifloxacin 400 mg daily for 7 days

This sequential approach achieves cure rates of approximately 92–95% in clinical studies.

Why resistance matters: The MyGeniUS surveillance study found that 59.1% of M. genitalium strains in U.S. STI clinics carried macrolide resistance mutations — meaning azithromycin alone will fail in the majority of cases. This is why resistance testing, when available, directly improves treatment success.

Test of cure: A follow-up NAAT should be performed at least 21 days after completing treatment to confirm the infection has cleared.

Can Mycoplasma Genitalium Cause Long-Term Complications?

Yes. While the bacterium itself is treatable, delayed or missed diagnosis can lead to significant complications:

In women:

• Pelvic inflammatory disease (PID) — which can cause chronic pelvic pain

• Tubal-factor infertility

• Increased risk of preterm delivery during pregnancy

• Cervicitis

In men:

• Persistent or recurrent urethritis

• Epididymitis (less well-established, but reported)

The relationship between untreated M. gen and female infertility is supported by sero-epidemiologic studies, even after accounting for prior chlamydial infection. This is why I consider early detection critically important, even in asymptomatic individuals who have known risk factors.

When to Seek Urgent Care

Seek emergency care immediately if you experience:

• Severe lower abdominal pain with fever above 101°F (may indicate PID or another acute infection)

• Testicular swelling with fever and inability to urinate

• Signs of systemic infection: high fever, chills, rapid heart rate

Call your doctor within 24 hours if:

• You have persistent burning during urination after completing antibiotic treatment

• You notice abnormal discharge that returns after treatment

• A sexual partner has been diagnosed with M. genitalium

• You experience bleeding between periods or after sex

Frequently Asked Questions

Can mycoplasma genitalium go away on its own?

There is no reliable evidence that M. gen clears spontaneously. While some infections may eventually resolve without treatment, the timeline is unpredictable, and you remain contagious during that entire period. Antibiotic treatment is the recommended approach.

Can you get mycoplasma genitalium from oral sex?

M. genitalium has been detected in oropharyngeal specimens, but pharyngeal infection appears to be uncommon, and the bacterium does not seem to cause pharyngitis. Oral-to-genital transmission is theoretically possible but is not considered a primary transmission route based on current evidence.

What is the difference between mycoplasma genitalium and ureaplasma?

Both are small bacteria from the Mycoplasmataceae family, and both can infect the urogenital tract. However, they are distinct organisms. M. genitalium is more clearly linked to clinical syndromes like urethritis and PID. Ureaplasma is more commonly part of normal genital flora, though it can also cause problems in certain situations.

Can mycoplasma genitalium be dormant?

"Dormant" is not the precise clinical term, but asymptomatic infection — where the bacterium is present and detectable but causes no symptoms — is extremely common. You can carry M. gen for months or longer without any signs of infection while still being able to transmit it to partners.

Why isn't mycoplasma genitalium included in standard STI testing?

Several factors contribute: the FDA-cleared test has only been available since 2019, awareness among providers is still growing, and there is ongoing debate in the medical community about whether routine screening of asymptomatic individuals does more good or harm, given antibiotic resistance concerns. Current guidelines reserve testing for symptomatic patients and partners of confirmed cases.

Is mycoplasma genitalium more common than chlamydia?

In the general U.S. population, M. gen prevalence (1.7%) is lower than chlamydia. However, among young women aged 21–24, the prevalence of M. gen approaches that of chlamydia. In STI clinic populations, M. gen prevalence can reach 16–17%, making it one of the most common bacterial STIs detected.

The Bottom Line

Mycoplasma genitalium is an increasingly recognized STI that most people have never heard of. It often produces no symptoms, is not included in routine testing, and has become increasingly resistant to common antibiotics. The most important thing to know is that if you have persistent urethritis, unexplained pelvic symptoms, or a partner who has tested positive — ask your provider for a specific M. gen test. Early detection and resistance-guided treatment offer the best outcomes.

If you're concerned about M. gen or any STI, getting tested is the single most important step you can take. Confidential testing is available in New York City, Los Angeles, Chicago, Houston, and Miami.

Related reading: Can You Have an STD With No Symptoms? · The Rise of Antibiotic-Resistant STDs · How Often Should You Get Tested? · Chlamydia: Why Regular Testing Matters · STI Epidemic: Why Rates Are Surging