Mycoplasma pneumoniae is a type of bacteria. Infection with this microbe usually creates a mild illness that is seen most in older children and young adults.
Most illnesses caused by M. pneumoniae are mild and will go away after a number of weeks without any treatment. Only the more serious cases of infection may need the attention of doctors.
M. pneumoniae is the cause of one of the "atypical pneumonias." These are forms of lung infections that do not get better in response to the usual antibiotic treatments for most pneumonias.
M. pneumoniae has been estimated to be responsible for 10 to 40 percent of all pneumonia cases contracted in the community: those that are not picked up in hospitals or clinics.
Contents of this article:
Who gets Mycoplasma pneumoniae?
M. pneumoniae infection affects young adults and older children the most. Some groups of people are more at risk of illness, such as older adults and people with weakened immune systems.
Older adults are more at risk of Mycoplasma pneumoniae infection than others.
Outbreaks of the infection are most likely to occur where groups of people mix closely. Such places include schools and nursing homes.
The spread of M. pneumoniae from person to person is a relatively gradual process but one that is seen commonly among the same members of a single household.
The bacteria do not spread as easily as other respiratory infections, and it can take as long as 3 weeks before symptoms appear. Infection spreads when droplets containing the bacteria are passed across in the air by coughing or sneezing.
This spread can only happen when people are in close contact because M. pneumoniae dries out easily - it needs to survive in water droplets.
When it gets into the upper airways, M. pneumoniae are very difficult to remove from the body. The bacteria have special adaptations that enable them to stick to cells. It is through this ability that they cause damage and trigger a fight with the immune system, creating the symptoms of illness.
Symptoms of Mycoplasma pneumoniae infection
Most cases of M. pneumoniae infection last in a mild form for several weeks.
The typical symptoms are those of a chest cold:
The symptoms of M. pneumoniae infection and many other respiratory infections are very similar. The key feature of M. pneumoniae infection is a lasting cough.
When M. pneumoniae causes an infection deeper in the lung, there is a range of possible symptoms that are more of a problem. In addition to the above symptoms, patients may also feel that breathing is affected. There may be some pain in the chest that feels worse with breathing or coughing.
Breathing may be more rapid, or shallow, which means less ability for deeper breaths. The heart rate may also be higher, and there may be a more general feeling of being unwell, perhaps with sweating, shivering, and loss of appetite.
M. pneumoniae infection may cause wheezing. Infection with the bacteria may also make asthma worse.
Complications of M. pneumoniae are rare. Doctors will be more alert to their possibility in people who already have a lung disease such as asthma or chronic obstructive pulmonary disease (COPD).
People over 65 years of age are more at risk than many. A weakened immune system also makes a person more at risk of complications.
Anyone with a long-term disease or who has been told by their doctor that they may be more vulnerable to illness should tell a doctor whenever they get an infection.
More severe disease as a complication of M. pneumoniae includes the examples of severe pneumonia and inflammation of the brain.
Anyone who has symptoms that make breathing difficult should see a doctor as soon as possible.
Diagnosis of Mycoplasma pneumoniae infection
Doctors diagnose M. pneumoniae based on the symptoms reported by the patient, including things such as how long symptoms have lasted.
Doctors will listen to a patient's lungs to help diagnose an infection.
The doctor will also listen to the chest and check the throat during a physical examination of the person overall.
Diagnosing an M. pneumoniae infection can be difficult because it can be more subtle than other forms of lung infection. Other infections tend to produce lung sounds for the doctor to hear, for example.
A pneumonia of any cause is generally diagnosed based on the symptoms, history, and other problems being ruled out. X-ray images may be ordered for more severe cases of pneumonia.
Diagnosing pneumonia as caused by M. pneumoniae usually only happens after other types of pneumonia have been ruled out. This might happen when the pneumonia has failed to respond to the usual treatment, which is designed to kill other types of bacteria.
Lab tests for Mycoplasma pneumoniae
It is difficult to do the biological tests to make certain of M. pneumoniae infection. Lab options are unreliable, expensive, not widely available, or take a long time.
It is often simpler to diagnose M. pneumoniae infection by ruling out other problems.
Testing for the bacteria is not usually recommended to diagnose a mild pneumonia infection. It is reserved for the more serious cases of illness that could benefit from drug treatment.
If a lab confirmation of the bacteria is needed, the sample tested can be from sputum, a swab of the throat, or a wash from the upper tubes of the lung. These tests are to detect the microbes directly.
Quicker tests are done using a sample of blood to find indirect evidence of the infection. These blood tests look for antibodies to the infection.
Treatment of Mycoplasma pneumoniae infection
Most cases of M. pneumoniae do not need any treatment. Most infections run their course without causing serious problems. Full health returns after a number of weeks, although the cough may last longer.
Resting and increasing fluid intake can help the immune system fight off an M. pneumoniae infection.
Resting at home when feeling unwell and drinking enough fluid helps the immune system, avoids problems such as losing too much fluid, and helps prevent spread.
Some symptoms such as headache or sore throat may be eased by over-the-counter medication.
Doctors may prescribe antibiotics if there is a case of infection deeper in the lungs. In children, pneumonia is usually treated first with antibiotics that do not work against M. pneumoniae. When this is discovered to have been the case, the drugs are then switched to a group of antibiotics known as macrolides.
Broader antibiotics are tried first and as soon as possible. The reason for this is that most cases of pneumonia turn out to respond well to these drugs. There is no reliable way to tell the more common pneumonia infections from ones caused by M. pneumoniae.
Anyone with complications of pneumonia will be treated for these, too. Some people may need to be treated intensively in a hospital if their blood pressure is low or they need help with breathing.
When a case of pneumonia is diagnosed as being caused by M. pneumoniae, treatment with macrolide antibiotics remains the recommendation even though there has been increasing resistance to the drug. This means that the drug has become ineffective in an increasing number of cases.
The potential problem is not relevant to most cases of M. pneumoniae infection, which resolve without medical intervention.
If an infection with M. pneumoniae does show resistance to macrolides, doctors can switch to other antibiotics. They may need to do this in younger children even if the particular antibiotic would not normally be recommended for their use.
Doctors try to be as sure as possible about the need for antibiotics before starting a course, which should be taken in full.
Prevention of Mycoplasma pneumoniae infection
As with any other upper respiratory tract infection, prevention may be helped by avoiding close contact with people known to have the infection already, or who are unwell or have a cough.
Because M. pneumoniae is spread by droplets in the air, people with a cough can help by keeping it from reaching other people.