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Ureaplasma is a genus of bacteria that primarily infects the genitals and urinary tract. It can be passed through sexual contact but is not considered a sexually transmitted infection (STI) because of its low degree of pathogenicity (capacity to cause disease).
It is estimated that a large proportion of the sexually active population is infected with Ureaplasma without it causing any symptoms. However, when a person's immune system is low and the bacterium overgrows, it can cause urethritis (inflammation of the urethra) or bacterial vaginosis and possibly contribute to infertility.
Some infections will clear up on their own; others need to be treated with a course of antibiotics.
This article explains what Ureaplasma is, including the symptoms, modes of transmission, and methods of diagnosis. It also explains how infections are prevented and treated and the possible complications of an untreated infection.
Ureaplasma belongs to a class of bacteria known as mycoplasma. These are the smallest self-replicating organisms known in nature and ones that tend to be commensal in the human body (meaning cohabitate with other organisms without causing damage).
There are two major strains known as Ureaplasma urealyticum and Ureaplasma parvum .
Females (people with a vagina) appear more vulnerable to Ureaplasma infections than males (people with a penis). Studies suggest that infection rates may be as high as 40% to 80% in females and up to 50% in males.
Once infected, Ureaplasma will inhabit mucosal tissues of the genital and urinary tract but usually are well controlled by the immune system, causing little if any harm. As such, testing positive for the Ureaplasma in and of itself does not mean anything.
It is only when the bacteria overgrows and establishes a symptomatic infection that a person may need treatment. An active infection may also place a person of any sex at an increased risk of infertility.
If Ureaplasma is well-controlled and living in check with other organisms in the genital microbiome, it will not cause any symptoms. In fact, the vast majority of Ureaplasma infections are asymptomatic (without symptoms) and may never cause any symptoms.
However, if the immune system cannot control the bacterium, Ureaplasma can overgrow and establish a symptomatic infection in the urinary and/or genital tract. This can lead to infections known as nongonococcal urethritis (NGU) or bacterial vaginosis (BV).
Urethritis is inflammation of the urethra (the tube through which urine exits the body). Nongonococcal urethritis occurs when the inflammation is caused by something other than gonorrhea .
While STIs like chlamydia are the most likely causes, NGUs can also be caused by viruses, bacteria, fungi, and parasites that are not exclusively transmitted by sex.
Studies vary, but some suggest that the incidence of Ureaplasma in people with NGU ranges from 32% to 44%.
Common symptoms of NGU include:
People with a penis may also experience balanitis (inflammation of the penis head) or posthitis (inflammation of the foreskin), while people with a vagina may experience cervicitis (inflammation of the cervix) and vaginal bleeding.
Bacterial vaginosis is a common condition in which the balance of bacteria in the vagina gets out of sync. Symptoms tend to be mild but can be persistent and difficult to treat.
Common symptoms of BV include:
While many people with BV are asymptomatic, studies suggest that those with Ureaplasma are 4 times more likely to experience symptoms compared to other common bacteria types.
Ureaplasma can be passed through sexual contact, including vaginal, oral, and anal sex. Although the vagina and penis are common sites of infection, Ureaplasma can also inhabit the mouth and rectum, though they don't typically cause any symptoms.
Ureaplasma can also be passed to a fetus or newborn during pregnancy. This can occur while the fetus is in the uterus (womb) or as it passes through the birth canal during delivery. The rate of Ureaplasma transmission from birthing parent to child is 15% to 88%.
Ureaplasma infection can be diagnosed with a urine sample or a swab of fluid from the vagina or urethra. The bacteria can be detected with polymerase chain reaction (PCR), a test that is able to multiply even small amounts of an organism's genetic material (DNA) to detectable levels.
The test is highly accurate, with a sensitivity of 96.5% and specificity of 93.6%. (Sensitivity refers to a test's ability to return a true positive result, while specificity is the ability to return a true negative result.) Results can usually be returned within 36 hours.
The PCR can also be used to detect Ureaplasma in the mouth, throat, rectum, and eyes.
At-home tests are available to detect Ureaplasma alone or as part of a panel of STIs. The cost of these tests is between $100 and $250.
The tests allow you to take a genital swab in the privacy of your home and mail it to a lab for testing. The results are usually returned via a secure website within two to three business days.
If you test positive for Ureaplasma during a symptomatic infection, your partner can also be tested or simply be treated under the presumption that they have Ureaplasma.
Outside of a symptomatic infection, the Centers for Disease Control and Prevention (CDC) does not recommend routine testing as the implication of a positive result may be negligible. In the end, having Ureaplasma does not mean that you will ever have symptoms or any health concerns.
The only exceptions may be for males who experience unexplained recurrent NGUs or females with unexplained recurrent cervicitis. In such cases, testing can help determine if Ureaplasma is the cause and direct the appropriate course of treatment.
As with any acute bacterial infection, the primary form of treatment for a symptomatic Ureaplasma infection is antibiotics. Even so, the treatment can be challenging due to the unique structure of the bacteria, which lacks a cell wall.
This makes certain antibiotics, like penicillins, ineffective against Ureaplasma because they work by blocking the formation of the cell wall as a bacterium multiplies, causing it to collapse and die.
Because of this unique feature, Ureaplasma and other mycoplasma bacteria require specific antibiotics to control the infection. These are taken orally (by mouth) and dosed in milligrams (mg).
The CDC currently recommends the following treatment regimens for mycoplasma-induced NGU and cervicitis, including Ureaplasma:
| Condition | Recommendation | Antibiotic Therapy |
|---|---|---|
| Urethritis | Preferred | Doxycycline 100 mg twice daily for seven days |
| Alternative | Azithromycin 1 gram (1,000 mg) in a single dose or azithromycin 500 mg in a single dose, followed by 250 mg daily for four days | |
| Cervicitis | Preferred | Doxycycline 100 mg twice daily for seven days |
| Alternative | Azithromycin 1 gram (1,000 mg) in a single dose |
In newborns, azithromycin can also be used. To prevent transmission of the bacterium, the drug may also be given to the pregnant person during the pregnancy either by mouth or intravenously (into a vein). Consultation with a specialist obstetrician is needed to make an informed choice.
Oftentimes, Ureaplasma infections will go away on their own without treatment, though antibiotics may be prescribed to speed the process.
With that said, studies have shown that certain mutations of the bacteria can evade immune detection and either persist or recur. Because of this, people with recurrent unexplained urinary tract infections should undergo testing to determine if Ureaplasma is the cause.
There is even evidence, though not conclusive, that Ureaplasma may cause unexplained infertility in some people. ("Infertility" is defined as the inability to conceive after trying for 12 months.)
This has been verified in studies in which Ureaplasma urealyticum is seen more frequently in females with unexplained infertility. Although study findings are inconsistent, Ureaplasma is also linked to pelvic inflammatory disease (PID), a condition that can also increase the risk of infertility.
In males, Ureaplasma (particularly Ureaplasma parvum) appears to lower not only the sperm count but also the proportion of forward-moving sperm cells.
Whether the infection alone is the cause of infertility is unknown. What is known is that recurrent NGU or cervicitis can independently increase the risk of infertility despite the type of causative agent.
Ureaplasma can affect a pregnancy, causing preterm birth (meaning birth before 32 weeks of gestation). Ureaplasma parvum is the species most commonly associated with this.
A 2014 study from the University of Maryland School of Medicine found that nearly half of all preterm births involved birthing parents with Ureaplasma. In such cases, the transmission occurred in utero (while in the uterus), causing infection in either the respiratory tract, nervous system, digestive tract, or multiple organ systems of the fetus.
Infection in these organs can lead to potentially severe complications in preterm babies, including:
While exposure to Ureaplasma on its own does not cause these complications—other factors such as low birth weight and being born before 29 weeks can contribute—an infection in newborns is independently linked to a fourfold increased risk of BPD, a three-fold increased risk of NEC, and a 2.5-fold increased risk of HH.
In adults, it is uncommon for Ureaplasma to disseminate (spread) and cause complications outside of the urinary and genital tracts. Even so, people who are severely immunocompromised are vulnerable to complications.
Among this group, rare complications have been reported, such as :
Severely immunocompromised people who experience these events—including organ transplant recipients and those with advanced, untreated human immunodeficiency virus (HIV)—should be tested for Ureaplasma to ensure the correct treatment is delivered.
Because Ureaplasma often causes no symptoms, it is possible to be reinfected without knowing. It is unclear if repeated infection poses any health concerns in the absence of symptoms.
On the other hand, recurrent NGU and cervicitis do pose health risks. So, the avoidance of reinfection is essential—particularly if you are trying to get pregnant.
If you have been diagnosed with Ureaplasma, you can take steps to reduce your risk of reinfection:
Safer sex is important as Ureaplasma is closely linked to the human papillomavirus (HPV). A 2018 International Journal of Infectious Diseases suggests that one in four females with Ureaplasma have a high-risk type of HPV (the types linked to an increased risk of cervical cancer).
Ureaplasma is a bacteria that can be passed through sex but is not a sexually transmitted infection because it can reside in the urinary and genital tracts without causing any symptoms. It can also be passed from birthing parent to child during pregnancy or delivery.
On occasion, Ureaplasma can overgrow and cause infections like nongonococcal urethritis or cervicitis. Possible complications include infertility and preterm birth.
Ureaplasma can be detected with a urine sample or swab of vaginal or urethral fluid. The infection may clear on its own or with a course of antibiotics, typically doxycycline or azithromycin.
30 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
By James Myhre & Dennis Sifris, MD
Dr. Sifris is an HIV specialist and Medical Director of LifeSense Disease Management. Myhre is a journalist and HIV educator.
