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Atypical pneumonia

  • Definition
    • Pneumonia is an infection of the lung.

      With atypical pneumonia, the infection is caused by different bacteria than the ones that cause typical pneumonia. These include Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydophila pneumoniae. Atypical pneumonia also tends to have milder symptoms than typical pneumonia.

  • Alternative Names
    • Walking pneumonia; Community-acquired pneumonia - atypical

  • Causes
    • Mycoplasma pneumonia is a type of atypical pneumonia. It is caused by the bacteria M. pneumoniae. It often affects people younger than age 40. Pneumonia due to chlamydia bacteria occurs year round. It is usually mild.

      Pneumonia due to Legionella is seen more often in middle-aged and older adults, smokers, and those with chronic illnesses or a weak immune system. It can be more severe. This type of pneumonia is also called Legionnaire disease.

  • Symptoms
    • Pneumonia due to mycoplasma and chlamydophila bacteria is usually mild.

      • Pneumonia due to Legionella pneumophila gets worse during the first 4 to 6 days, and then improves over 4 to 5 days.
      • Even though symptoms will improve, it may take a while for them to go away completely.

      The most common symptoms of pneumonia are:

      • Chills
      • Cough (with Legionella pneumonia, you may cough up bloody mucus)
      • Fever, which may be mild or high
      • Shortness of breath (may only occur when you exert yourself)

      Other symptoms include:

      • Chest pain that gets worse when you breathe deeply or cough
      • Confusion, especially in older people or those with Legionella pneumonia
      • Headache
      • Loss of appetite, low energy, and fatigue
      • Muscle aches and joint stiffness
      • Sweating and clammy skin

      Less common symptoms include:

      • Diarrhea (especially with Legionella pneumonia)
      • Ear pain (with mycoplasma pneumonia)
      • Eye pain or soreness (with mycoplasma pneumonia)
      • Neck lump (with mycoplasma pneumonia)
      • Rash (with mycoplasma pneumonia)
      • Sore throat (with mycoplasma pneumonia)
  • Exams and Tests
    • People with suspected pneumonia should have a complete medical evaluation. It may be hard for your health care provider to tell whether you have pneumonia or bronchitis, so you may need a chest x-ray. Depending on how severe the illness is, other tests may be done, including:

      Urine tests or a throat swab may also be done.

  • Treatment
    • To feel better, you can take these self-care measures at home:

      • Control your fever with aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen or naproxen), or acetaminophen. DO NOT give aspirin to children.
      • DO NOT take cough medicines without first talking to your doctor. Cough medicines may make it harder for your body to cough up the extra sputum.
      • Drink plenty of fluids to help loosen secretions and bring up phlegm.
      • Get a lot of rest. Have someone else do household chores.

      Antibiotics are used to treat atypical pneumonia.

      • You may be able to take antibiotics by mouth at home.
      • If your condition is severe, you will likely be admitted to a hospital. There, you will be given antibiotics through a vein (intravenously), as well as oxygen.
      • Antibiotics are used for 2 weeks or more
  • Outlook (Prognosis)
    • Most patients with pneumonia due to mycoplasma or chlamydophila get better with the right antibiotics. Legionella pneumonia can be severe. It can lead to problems, especially in patients with kidney failure, diabetes, COPD, or a weak immune system. It can also lead to death.

  • Possible Complications
      • Brain and nervous system infections, such as meningitis, myelitis, and encephalitis
      • Hemolytic anemia, a condition in which there are not enough red blood cells in the blood because the body is destroying them
      • Severe lung damage
  • When to Contact a Medical Professional
    • Contact your health care provider if you develop fever, cough, or shortness of breath. There are numerous causes for these symptoms. The doctor will need to rule out pneumonia.

  • Prevention
    • Wash your hands often and have other people around you do the same.

      If your immune system is weak, stay away from crowds. Ask visitors who have a cold to wear a mask.

      Do not smoke. If you do, get help to quit.

      Get a flu shot every year. Ask your doctor if you need a pneumonia vaccine.

  • References
    • Baum SG. Mycoplasma pneumonia and atypical pneumonia. In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2009:chap 184.

      Mandell LA, Wunderink RG, Anzueto A, et al. Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults. Clin Infect Dis. 2007;44:S27-S72. PMID: 17278083