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.
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Scientists have identified at least 16 species of these tiny bacteria; three have been linked to disease in humans, and researchers are looking at possible relationships between other species and a variety of diseases.
Mycoplasma pneumoniae (my-ko-PLAZ-muh nu-MO-nye) is the cause of atypical or “walking” pneumonia (nu-MO-nyah, 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 4 to 8 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 diseases (STDs) 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.
- (yoo-ree-THRY-tis) is inflammation of the urethra (yoo-REE-thra), which is the tube through which urine passes from the bladder out of the body.
- (vah-jih-NYE-tis) is inflammation of the vagina (vah-JY-nah), which is the canal in a woman that leads from the uterus to the outside of the body.
- means that a group of organisms, particularly bacteria, are living on or inside the body without causing symptoms of infection.
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.
The U.S. Centers for Disease Control and Prevention estimates that 2 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*.
- *sickle-cell disease
- 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.
Mycoplasma pneumonia most frequently affects people between the ages of 5 and 40; it is rarely seen in children under 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. To become infected, someone must have close contact with the sick person.
The time between exposure and the appearance of symptoms is relatively long (1 to 4 weeks), so the disease can spread for months within a home without family members realizing they are passing along the same infection. After a bout of Mycoplasma pneumoniae infection, antibodies* will protect a person from re-infection, but this immunity* does not last for life.
- (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.
- (ih-MYOON-uh-tee) is the condition of being protected against an infectious disease. Immunity often develops after a germ is introduced to 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.
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 will develop the more full-blown classic walking pneumonia.
- (LIMF) nodes are small, bean-shaped masses of tissue that contain immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.
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 will help 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.
- (KUL-churs) are tests in which samples of fluid or tissue from the body are placed in dishes containing material that supports the growth of certain organisms. Typically, within days the organisms will grow and can be identified.
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 also can 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 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, will 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 1 to 4 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-yan bah-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).
- (pah-RAH-luh-sis) is the loss or impairment of the ability to move some part of the body.
The best defenses against mycoplasma pneumonia are frequent, thorough hand washing and not sharing food, drinks, or eating utensils.
Mycoplasma hominis infects up to 30 to 50 percent of sexually active men and women. Ureaplasma urealyticum may infect more than half of sexually active women and 5 to 20 percent of sexually active men.
Twenty percent of newborns are colonized with these bacteria, but colonization rates drop significantly by 3 months of age. Premature infants have the greatest risk of colonization; up to half of all premature infants less than 34 weeks’ 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.
- (jes-TAY-shuh-nul) age is the length of time a fetus has remained developing within the womb.
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 STDs. 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-e-o-am-nee-ahn-EYE-tis), which has been linked to a greater risk of stillbirth* and premature delivery*.
- *pelvic inflammatory disease
- refers to an infection of a woman’s internal reproductive organs, including the fallopian tubes, uterus, cervix, and ovaries.
- is the birth of a dead fetus.
- *premature delivery
- is when a baby is born before it has reached full term.
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 where 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 1 to 2 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.
- (in-fer-TIH-lih-tee) is the inability of females to become pregnant or of males to cause pregnancy.
Because many people carry genital mycoplasma bacteria but do not know they are infected, preventing their spread is difficult. Abstaining from all forms of sex (not having sex) is the only sure way to prevent infection.
Sexually Transmitted Diseases
Urinary Tract Infections
U.S. Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, Atlanta, GA 30333. The CDC is the U.S. government authority for information about infectious and other diseases. It provides information about mycoplasma infections at its website. Telephone 800-311-3435 http://www.cdc.gov
KidsHealth.org. KidsHealth is a website created by the medical experts of the Nemours Foundation and is devoted to issues of children’s health. It contains articles on a variety of health topics, including mycoplasma pneumonia.
Mycoplasma are bacteria that lack a conventional cell wall. They are capable of replication. Mycoplasma cause various diseases in humans, animals, and plants.
There are seven species of mycoplasma that are known to cause disease in humans. Mycoplasma pneumoniae is an important cause of sore throat, pneumonia , and the inflammation of the channels in the lung that are known as the bronchi. Because of the atypical nature of the bacterium, mycoplasmainduced pneumonia is also referred to as atypical pneumonia. The pneumonia can affect children and adults. The symptoms tend to be more pronounced in adults. In fact, children may not exhibit any symptoms of infection. Symptoms of infection include a fever, general feeling of being unwell, sore throat, and sometimes an uncomfortable chest. These symptoms last a week to several months and usually fade without medical intervention.
Mycoplasma pneumoniae can also cause infections in areas of the body other than the lungs, including the central nervous system, liver, and the pancreas.
Another species, Mycoplasma genitalium, is associated with infections of the urethra, especially when the urethra has been infected by some other bacteria. The mycoplasma infection may occur due to the stress imposed on the immune system by the other infection.
A mycoplasma called Ureaplasma urealyticum is present in the genital tract of many sexually active women. The resulting chronic infection can contribute to premature delivery in pregnant women. As well, the mycoplasma can be transmitted from the mother to the infant. The infant can contract pneumonia, infection of the central nervous system, and lung malfunction.
A group of four mycoplasma species are considered to be human pathogens and may contribute to the development an immunodeficiency virus infection to the more problematic and debilitating symptoms of Acquired Immunodeficiency Syndrome (AIDS ). The species of mycoplasma are Mycoplasma fermentans, Mycoplasma pirum, Mycoplasma hominis, and Mycoplasma penetrans.
Mycoplasma have also been observed in patients who exhibit other diseases. For example, studies using genetic probes and the polymerase chain reaction technique of detecting target DNA have found Mycoplasma fermentans in upwards of 35% of those afflicted with chronic fatigue syndrome. The bacterium is present in less than 5% of healthy populations. Similar percentages have been found in soldiers of the Persian Gulf War who are exhibiting chronic fatigue-like symptoms. While the exact relationship between mycoplasma and the chronic fatigue state is not fully clear, the current consensus is that the bacteria is playing a secondary role in the development of the symptoms.
Over 20 years ago, mycoplasma was suggested as a cause of rheumatoid arthritis. With the development of molecular techniques of bacterial detection, this suggestion could be tested. The polymerase chain reaction has indeed detected Mycoplasma fermentans in a significant number of those afflicted with the condition. But again, a direct causal relationship remains to be established.
The association of mycoplasma with diseases like arthritis and chronic fatigue syndrome, which has been implicated with a response of the body's immune system against its own components, is consistent with the growth and behavior of mycoplasma. The absence of a conventional cell wall allows mycobacteria to penetrate into the white blood cells of the immune system. Because some mycoplasma will exist free of the blood cells and because the bacteria are capable of slow growth in the body, the immune system will detect and respond to a mycobacterial infection. But this response is generally futile. The bacteria hidden inside the white blood cells will not be killed. The immune components instead might begin to attack other antigens of the host that are similar in three-dimensional structure to the mycobacterial antigens. Because mycoplasma infections can become chronic, damage to the body over an extended time and the stress produced on the immune system may allow other microorganisms to establish infections.
The polymerase chain reaction is presently the best means of detecting mycoplasma. The bacteria cannot be easily grown on laboratory media. Labs that test using the polymerase technique are still rare. Thus, a mycoplasma infection might escape detection for years.
Strategies to eliminate mycoplasma infections are now centering on the strengthening of the immune system, and long-term antibiotic use (e.g., months or years). Even so, it is still unclear whether antibiotics are truly effective on mycoplasma bacteria. Mycoplasma can alter the chemical composition of the surface each time a bacterium divides. Thus, there may be no constant target for an antibiotic.
See also Bacteria and bacterial infection; Bacterial membranes and cell wall
Mycoplasma are the smallest of the free-living organisms. (Unlike viruses, mycoplasma can reproduce outside of living cells.) Many species within the genus Mycoplasma thrive as parasites in human, bird, and animal hosts. Some species can cause disease in humans.
Mycoplasma are found most often on the surfaces of mucous membranes. They can cause chronic inflammatory diseases of the respiratory system, urogenital tract, and joints. The most common human illnesses caused by mycoplasma are due to infection with M. pneumoniae, which is responsible for 10-20% of all pneumonias. This type of pneumonia is also called atypical pneumonia, walking pneumonia, or community-acquired pneumonia. Infection moves easily among people in close contact because it is spread primarily when infected droplets circulate in the air (that is, become aerosolized), usually due to coughing, spitting, or sneezing.
Causes and symptoms
Atypical pneumonias can affect otherwise healthy people who have close contact with one another. Pneumonia caused by M. pneumoniae may start out with symptoms of an upper respiratory infection, probably a sore throat progressing to a dry cough within a few days. Gradually, fever, fatigue, muscle aches, and a cough that produces thin sputum (spit or phlegm) will emerge. Nonrespiratory symptoms may occur too: abdominal pain, headache, and diarrhea ; about 20% of patients may have ear pain.
Another mycoplasma species, M. hominis, is common in the mucous membranes of the genital area (including the cervix), and can cause infection in both males and females. Its presence does not always result in symptoms.
Usually, mycoplasma pneumonia will be identified after other common diagnoses are set aside. For example, a type of antibiotic known as a beta-lactam might be prescribed for a respiratory infection producing fever and cough. If symptoms do not improve in 3-5 days, the organism causing the disease is not a typical one and not susceptible to these antibiotics. If a Gram's stain (a common test done on sputum) does not indicate a gram-positive pathogen, the doctor will suspect a gram-negative organism, such as mycoplasma. The actual underlying organism may not be identified (it is not in almost 50% of cases of atypical pneumonia). Although it is rare, a rash may appear along with pneumonia symptoms. This should trigger suspicion of mycoplasma pneumonia, even if laboratory tests are inconclusive.
Standard x rays may reveal a patchy material that has entered the tissue; this can be evident for months. Laboratory tests include cold agglutinins, complement fixation, culture, and enzyme immunoassay. The presence of infection with M. pneumoniae would be indicated by a fourfold rise in M. pneumoniae -specific antibody in serum, during the illness or convalescence. Highly sophisticated and specific polymerase chain reaction methods (PCR) have been developed for many respiratory pathogens, including M. pneumoniae. They are not readily available and are very expensive.
Community-acquired— Refers to an infectious disease that is passed among individuals who have close contact with one another.
A 2-3 week course of certain antibiotics (erythromycin, azithromycin, clarithromycin, dirithromycin, or doxycycline) is generally prescribed for atypical pneumonia. This disease is infectious for weeks, even after the patient starts antibiotics. A persistent cough may linger for 6 weeks.
Mycoplasma pneumonia may be involved in the onset of asthma in adults; other rare complications include meningoencephalitis, Guillain-Barré syndrome, mononeuritis multiplex, myocarditis, or pericarditis. This may increase the risk of acute arrhythmias leading to sudden cardiac death. However, with proper treatment and rest, recovery should be complete.
At this time, there are no vaccines for mycoplasma infection. It is difficult to control its spread, especially in a group setting. The best measures are still the simplest ones. Avoid exposure to people with respiratory infections whenever possible. A person who has a respiratory infection should cover the face while coughing or sneezing.
Cassell, Gail H., Gregory G. Gray, and K. B. Waites. "Mycoplasma Infections." In Harrison's Principles of Internal Medicine, edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1997.