Atypical pneumonia

Definition

Pneumonia is inflamed or swollen lung tissue due to infection with a germ.

With atypical pneumonia, the infection is caused by different bacteria than the more common ones that cause pneumonia. Atypical pneumonia also tends to have milder symptoms than typical pneumonia.

Alternative Names

Walking pneumonia; Community-acquired pneumonia - atypical

Causes

Bacteria that cause atypical pneumonia include:

Symptoms

Pneumonia due to mycoplasma and chlamydophila bacteria is usually mild. Pneumonia due to legionella gets worse during the first 4 to 6 days, and then improves over 4 to 5 days.

The most common symptoms of pneumonia are:

Other symptoms include:

Less common symptoms include:

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, bronchitis, or another respiratory infection, so you may need a chest x-ray. The evaluation is similar for people who have more typical pneumonia.

Depending on how severe the symptoms are, other tests may be done, including:

Treatment

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

If needed, you will be prescribed antibiotics.

Outlook (Prognosis)

Most people with pneumonia due to mycoplasma or chlamydophila get better with the right antibiotics. Legionella pneumonia can be severe. It can lead to problems, most often in those with kidney failure, diabetes, chronic obstructive pulmonary disease (COPD), or a weakened immune system. It can also lead to death.

Possible Complications

Complications that may result include any of the following:

When to Contact a Medical Professional

Contact your provider if you develop fever, cough, or shortness of breath. There are many causes for these symptoms. The provider will need to rule out pneumonia.

Also, call if you have been diagnosed with this type of pneumonia and your symptoms become worse after improving first.

Prevention

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

Avoid contact with sick people whenever possible.

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 appropriate vaccines like flu and COVID-19 shot as prescribed. Ask your provider if you need a pneumonia vaccine.

References

Baum SG, Goldman DL. Mycoplasma infections. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 301.

Holzman RS, Simberkoff MS, Leaf HL. Mycoplasma pneumoniae and atypical pneumonia. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 183.

Waxman MA, Moran GJ. Pneumonia. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 62.


Review Date: 7/31/2022
Reviewed By: Denis Hadjiliadis, MD, MHS, Paul F. Harron Jr. Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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