Atypical Pneumonia
Pneumonia is an infection that causes inflammation of the lungs. Atypical pneumonia is a kind that isn't caused by the bacteria that causes typ...

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What Is Atypical Pneumonia?

Pneumonia is an infection that causes inflammation of the lungs. Atypical pneumonia is a pneumonia that isn’t caused by the bacteria that causes typical pneumonia. Typical pneumonia tends to be more serious than atypical pneumonia.

This type of pneumonia is also sometimes referred to as “walking pneumonia” because it rarely requires bed rest or hospitalization.

What Are the Types of Atypical Pneumonia?

Atypical pneumonia is caused by one of three types of bacteria:

  • Legionella pneumophila (L. pneumophila)
  • Mycoplasma pneumoniae (M. pneumoniae)
  • Chlamydophila pneumonia (C. pneumoniae)

Mycoplasma Pneumonia

Mycoplasma pneumonia tends to affect people under the age of 40. It’s estimated that at least 2 million cases happen every year.

This condition most often occurs in people working or living in heavily populated areas such as schools, prisons, homeless shelters, and group homes. However, many people are diagnosed without any specific risk factors.

Legionella Pneumonia

Legionella pneumonia is also known as Legionnaires’ disease. It can occur when you breathe in water vapors infested with L. pneumophila. This bacteria is usually found in the water supply of buildings or cooling towers. It can be much more severe than the other types of walking pneumonia.

Outbreaks of this condition occur when two people get sick and seem to have contracted it from the same place. Local health departments investigate potential outbreaks.

Not everyone who is exposed to the infection becomes sick. Risk factors that put you at a higher risk for this condition include:

  • smoking
  • older age
  • a weak immune system
  • other chronic illness

Pontiac fever is a less severe infection caused by this bacteria. People who have Pontiac fever don’t have pneumonia. The symptoms of Pontiac fever include a headache, fever, and body aches.

You should see your doctor if you think you’ve been exposed to this bacteria.

Chlamydophila Pneumonia

This type of pneumonia occurs throughout the year. It presents very mild symptoms and rarely causes serious cases.

This condition is most common in school-age children. It’s estimated that 50 percent of adults have had this condition by age 20.

What Are the Symptoms of Atypical Pneumonia?

The symptoms associated with atypical pneumonia are generally mild. They may include:

  • chills
  • cough
  • headache
  • fever
  • muscle aches
  • muscle stiffness
  • loss of appetite
  • shortness of breath
  • rapid breathing

Mycoplasma pneumonia is also associated with a rash.

If you have Legionella pneumonia in particular, you also may have diarrhea and confusion.

When to See Your Doctor

It can be very difficult to tell the difference between a bad cold and atypical pneumonia. See your doctor if you’re recovering from a cold, but then you suddenly get worse and develop frequent coughing, fever, or chills.

You should also see your doctor if:

  • you have chest pain when you cough or breathe
  • you become short of breath
  • your cough is preventing you from sleeping

How Is Atypical Pneumonia Diagnosed?

Your doctor will perform a physical exam. You may also need a chest X-ray for diagnosis. A chest X-ray can distinguish between pneumonia and other respiratory illness, such as acute bronchitis.

Depending on your symptoms, you may need other tests. Some tests use to diagnose pneumonia include:

  • a culture of mucus from your lungs, which is called sputum
  • a sputum gram stain study
  • a throat swab
  • a complete blood count (CBC)
  • blood tests for specific antibodies
  • blood cultures

How Is Atypical Pneumonia Treated?

Antibiotics are used to treat the specific bacteria causing your condition. For mild cases, you will take antibiotics by mouth. In more severe cases, you may get them through an IV.

Some people with severe atypical pneumonia may need supplemental oxygen.

What Can Be Expected in the Long Term?

Most people who have walking pneumonia recover completely with antibiotics. However, it’s important to take your entire prescription. There’s a risk that the infection may return if the antibiotics are stopped early.

Complications can happen if atypical pneumonia is not treated quickly.

Most atypical pneumonia causes only mild symptoms. 

Written by: Elly Dock and Elizabeth Boskey, PhD
Edited by:
Medically Reviewed by: [Ljava.lang.Object;@5212f4b8
Published: Jul 25, 2012
Published By: Healthline Networks, Inc.
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