Conditions InDepth: Pneumonia

Pneumonia is a serious infection of the lungs that causes the air sacs in the lungs to fill with pus and other liquid. The infection may be caused by any of the following causative agents: bacteria, virus, fungi, mycoplasma, or chemicals. In general, pneumonia is divided into two types: community-acquired or hospital or nursing home-acquired.


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You may get pneumonia simply because you encounter an organism that you breathe into your lungs. Whether or not you get sick depends on the contagiousness of the organism, the number of organisms you inhaled, and the ability of your immune system to fight infections. Or, you may have another infection, which travels through your bloodstream to infect your lungs. (This is very rare, however.)

In the United States, pneumonia is a very common illness, with about 5 million cases occurring every year. The economic burden for the nation is approximately $39 billion a year. Over 67,000 Americans die each year from pneumonia, making pneumonia the eighth most common cause of death in the US.

What are the risk factors for pneumonia?
What are the symptoms of pneumonia?
How is pneumonia diagnosed?
What are the treatments for pneumonia?
Are there screening tests for pneumonia?
How can I reduce my risk of pneumonia?
What questions should I ask my doctor?
Where can I get more information about pneumonia?


American Lung Association website. Available at: . July 17, 2008.

DynaMed. Available at: Accessed on July 17, 2008

Koulenti D, Rello J. Hospital-acquired pneumonia in the 21st century: a review of existing treatment options and their impact on patient care. Expert Opin Pharmacother. 2006;7:1555-1569.

National Heart, Lung, and Blood Institute website. Available at: . Accessed July 17, 2008.

Primary Care Medicine . 4th ed. Lippincott Williams and Wilkins; 2000.

Last reviewed July 2008 by Marcin Chwistek, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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