Mycoplasma Infections

Mycoplasma (my-ko-PLAZ-muh) infections are caused by a type of very small bacteria. These infections usually involve the lungs or the urinary and genital tracts.

What Are Mycoplasma Infections?

Scientists have identified at least 16 species of these tiny bacteria; three have been linked to disease in humans, and researchers have explored possible relationships between other species and a variety of diseases.

Mycoplasma pneumoniae is the cause of atypical or “walking” pneumonia. The illustration shows the bacteria in the lung.

Mycoplasma pneumoniae is the cause of atypical or “walking” pneumonia. The illustration shows the bacteria in the lung.
Monica Schroeder/Science Source.

Mycoplasma pneumoniae (my-ko-PLAZ-muh nu-MO-nye) is the cause of atypical pneumonia (called “walking pneumonia”) (nu-MOnyah, inflammation in the lungs), a form of pneumonia that is characterized by symptoms similar to those of the flu and is generally less serious than other types of pneumonia. Widespread outbreaks of mycoplasma pneumonia occur every four to eight years. Most people recover without lasting effects, but elderly patients and people with weak immune systems may experience complications from the infection.

Commonly found in the genital and urinary tracts of adults, Mycoplasma hominis (HAH-mih-nis) and Ureaplasma urealyticum (yoo-REE-uh-plaz-muh yoo-ree-uh-LIH-tih-kum) are known as the genital mycoplasmas. These organisms can cause urethritis * and contribute to vaginitis * in women. They have been associated with sexually transmitted infections (STIs) and with chronic infections in people with weakened immune systems. Up to 50 percent of sexually active women are colonized * with U. urealyticum, which can spread to newborn babies during delivery. In premature infants, U. urealyticum may contribute to pneumonia and other infections, as well as to chronic lung disease.

Because these organisms are also found in healthy people and infants, their presence in someone who is sick does not necessarily mean mycoplasma is the culprit behind that particular infection. Although mycoplasma species such as U. urealyticum or M. hominis may be responsible for some infections, in many cases, it appears that they help start or worsen an illness that is actually caused by another infectious organism.

Mycoplasma Pneumonia

The Centers for Disease Control and Prevention estimates that two million people contract mycoplasma pneumonia in the United States each year. Of these, 100,000 require hospitalization. Fatal cases are rare and usually occur in the elderly and in people with sickle cell disease * .

Mycoplasma pneumonia most frequently affects people between the ages of 5 and 40; it is rarely seen in children under the age of 5. Outbreaks are common in groups of young adults, often in places where people are crowded together, such as in military facilities and college dormitories.

Mycoplasma is contagious, spreading through tiny drops of moisture from the nose and throats of infected people when they cough, sneeze, laugh, or talk. Sharing drinking glasses or eating utensils can spread the bacteria as well. Engaging in sexual activity without the use of a condom invites infection from sexually transmitted bacteria. In all cases, to become infected, someone must have close contact with the sick person.

* will protect a person from re-infection, but this immunity * does not last for life.

Signs and symptoms

Symptoms of mycoplasma pneumonia infection come on gradually. Many people have symptoms similar to those of the flu, such as sore throat, headache, weakness, fever, cough, and chills. Less common symptoms include earaches, eye pain, muscle aches, joint stiffness, skin rash, swollen lymph nodes * in the neck, and difficulty breathing. Some people have only a mild illness, whereas others develop the more full-blown classic walking pneumonia.


The physical exam is an important part of diagnosing mycoplasma pneumonia. A school-age child with fever, a cough, and wheezing or crackling sounds in the lungs may have mycoplasma. A chest x-ray helps confirm the diagnosis. Doctors do not usually order cultures * on samples of fluid from the nose or throat because the mycoplasma bacteria do not grow easily in cultures.

Although blood tests are not helpful in making a diagnosis early on, after about a week of illness, a blood test known as cold agglutinins (uh-GLOO-tuh-nins) is positive in half to three-fourths of all patients. This test is not specific for M. pneumoniae (other infections can also give a positive test result), but information from it can help support a diagnosis of suspected walking pneumonia. Tests for specific antibodies produced by the body in response to mycoplasma require at least two blood samples over time to show the body's response to the infection.


Antibiotics * , along with rest and fluids, help most patients recover. Some people get better without medicine, especially those who have only a mild illness. In severe cases, patients may need to be hospitalized so they can receive oxygen and other breathing support.

Symptoms usually last from one to four weeks, although the dry cough and extreme tiredness may linger for several more weeks.


Few people die from mycoplasma pneumonia, but the elderly are most at risk. Complications are not common but can include acute respiratory distress (extreme difficulty in breathing) and respiratory failure.

Other complications are even rarer: pericarditis (per-ih-kar-DYE-tis, inflammation of the sac around the heart); anemia (uh-NEE-me-uh, a deficiency of red blood cells); and diseases of the central nervous system * , including Guillain-Barré syndrome (gee-YAH ba-RAY SIN-drome, a temporary inflammation of the nerves that causes muscle weakness and paralysis * ), encephalitis (en-seh-fuh-LYE-tis, inflammation of the brain), and meningitis (meh-nin-JY-tis, inflammation of the membranes lining the brain and spinal cord).


The best defenses against mycoplasma pneumonia are frequent, thorough hand washing and not sharing food, drinks, or eating utensils.

Genital Mycoplasma Infection

M. hominis infects up to 30 to 50 percent of sexually active men and women. U. urealyticum may infect more than half of sexually active women and 5 to 20 percent of sexually active men. The habitual use of condoms during sexual activity helps prevent infection from these bacteria.

Twenty percent of newborns are colonized with these bacteria, but colonization rates drop significantly by three months of age. Premature infants have the greatest risk of colonization; up to half of all premature infants less than 34 weeks of gestational * age whose mothers are colonized may pick up the bacteria during birth. Genital mycoplasmas spread through direct contact during all forms of sexual intercourse. Mothers also can pass the bacteria to their babies during pregnancy and delivery.

Signs and symptoms

Most people with genital mycoplasma infection have no symptoms. Those who do may have a discharge (flow of fluid) from the urethra and pain or difficulty urinating. In rare cases, symptoms can include respiratory problems and joint pain, usually in people with weak immune systems.

Occasionally, women develop urethritis from mycoplasma infection, and although genital mycoplasma does not cause vaginitis, it may contribute to infections caused by other vaginal organisms, resulting in vaginal discharge. Pelvic (lower belly) pain may be a symptom of pelvic inflammatory disease * brought on by mycoplasma, alone or with other STIs. In pregnant women, U. urealyticum can cause inflammation of the membranes and fluid surrounding the unborn baby called asymptomatic chorioamnionitis (a-simp-toh-MAH-tik kor-ee-o-am-nee-ahn-EYE-tis), which has been linked to a greater risk of stillbirth * and premature birth * .

The symptoms of infection in newborns can be subtle. Fever, changes in blood pressure and heart rate, and difficulty breathing may be the first signs of a problem.


Samples are taken from the areas of suspected infection (such as a swab of discharge from the vagina), and the organism is grown with special culture techniques.


Antibiotics are prescribed to treat genital mycoplasma infections in people who have symptoms. In cases in which mycoplasma is found along with other disease-causing organisms, these other infections must be treated as well.

Genital mycoplasma infections generally respond to treatment within one to two weeks, although these infections commonly return.


Complications are rare in healthy adults but may include inflammation of other parts of the genital tract. Some adults, especially those with weakened immune systems, may have bone and joint infections, skin infections, and lung disease. The bacteria also have been linked to infertility * in women. Infected newborns, especially premature babies, may develop pneumonia or chronic lung disease and are at risk for meningitis and for spread of the disease throughout their bodies.


Because many people carry genital mycoplasma bacteria but do not know they are infected, preventing their spread is difficult. Regular use of condoms helps prevent the spread of many genital infections, including this one. However, abstaining from all forms of sex (not having sex) is the only sure way to prevent infection.

See also Bacterial Infections • Pneumonia • Sexually Transmitted Infections (STIs): Overview • Urinary Tract Infections


Books and Articles

Waites, Ken B. “Mycoplasma Infections.” Medscape, October 16, 2014. (accessed October 28, 2015).


Centers for Disease Control and Prevention. “Mycoplasma Pneumoniae Infection.” (accessed November 21, 2015).

Green, Nicole A. “Walking Pneumonia.” Nemours Children's Health System. (accessed November 21, 2015).

MedlinePlus. “Mycoplasma Pneumonia.” U.S. National Library of Medicine, National Institutes of Health. (accessed October 28, 2015).


Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329. Toll-free: 800-232-4636. Website: (accessed October 28, 2015).

* urethritis (yoo-ree-THRY-tis) is inflammation of the urethra (yooREE-thra), the tube through which urine passes from the bladder to the outside of the body.

* vaginitis (vah-jih-NYE-tis) is inflammation of the vagina (vahJY-nah), the canal, or passageway, in a woman that leads from the uterus to the outside of the body.

* colonized means that a group of organisms, particularly bacteria, are living on or inside the body without causing symptoms of infection.

* sickle cell disease, also called sickle cell anemia, is a hereditary condition in which the red blood cells, which are usually round, take on an abnormal crescent shape and have a decreased ability to carry oxygen throughout the body.

* antibodies (AN-tih-bah-deez) are protein molecules produced by the body's immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses.

* immunity (ih-MYOON-uh-tee) is the condition of being protected against an infectious disease. Immunity often develops after a germ has entered the body. One type of immunity occurs when the body makes special protein molecules called antibodies to fight the disease-causing germ. The next time that germ enters the body, the antibodies quickly attack it, usually preventing the germ from causing disease.

* lymph nodes (LIMF) are small, bean-shaped masses of tissue containing immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.

* cultures (KUL-churz) are tests in which a sample of fluid or tissue from the body is placed in a dish containing material that supports the growth of certain organisms. Typically, within days the organisms will grow and can be identified.

* antibiotics (an-tie-by-AH-tiks) are drugs that kill or slow the growth of bacteria.

* central nervous system (SEN-trul NER-vus SIS-tem) is the part of the nervous system that includes the brain and spinal cord.

* paralysis (pah-RAHL-uh-sis) is the loss or impairment of the ability to move some part of the body.

* gestational (jes-TAY-shun-al) means relating to pregnancy.

* pelvic inflammatory disease refers to an infection of a woman's internal reproductive organs, including the fallopian tubes, uterus, cervix, and ovaries.

* stillbirth is the birth of a dead fetus.

* premature birth (pre-ma-CHUB) means born too early. In humans, it means being born after a pregnancy term lasting less than 37 weeks.

* infertility (in-fer-TIH-lih-tee) is the inability of females to become pregnant or of males to cause pregnancy.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)