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Pneumonia Facts

  • Pneumonia is a lung infection that can be caused by different types of microorganisms, including bacteria, viruses, fungi, and parasites.
  • Symptoms of pneumonia may include
    • cough with sputum production,
    • fever,
    • sharp chest pain on inspiration (breathing in), and
    • shortness of breath.
  • Children and babies who develop pneumonia often do not have any specific signs of a chest infection but develop a fever, appear quite ill, and can become lethargic.
  • Pneumonia is suspected when a doctor hears abnormal sounds in the chest, and the diagnosis is confirmed by a chest X-ray.
  • Bacteria and fungi causing pneumonia can be identified by sputum culture. In some cases, detection of bacteria causing pneumonia can be done with urine tests (for example, Legionella, Pneumococcus). In others, blood tests demonstrate the body's immune response to certain infections. The results of these blood tests often identify the organism after the patient has recovered.
  • A pleural effusion is a fluid collection around the inflamed lung. This often results when the pneumonia is close to the chest wall and causes inflammation in the pleurae surrounding the lung.
  • Bacterial and fungal (but not viral) pneumonia can be treated with antibiotics and antifungal agents, respectively.

What Is the Definition of Pneumonia?

Pneumonia is an infection of one or both lungs that is usually caused by bacteria, viruses, fungi, or parasites. There are many different manifestations of pneumonias based on the type of microbe causing it. In some cases, a microbe can cause different kinds of pneumonia. Sometimes pneumonia affects a portion of one lung, and in other cases, the infection is diffuse throughout both lungs. Some cases of pneumonia can develop associated fluid collections. Some causes, like Staphylococcus aureus, can be very destructive to lung tissue. Prior to the discovery of antibiotics, one-third of all people who developed pneumonia subsequently died from the infection. Currently, over 3 million people develop pneumonia each year in the United States. Over a half a million of these people are admitted to a hospital for treatment. Although most of these people recover, approximately 5% will die from pneumonia. Pneumonia is the sixth leading cause of death in the United States.

Last Reviewed 8/30/2017

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Pneumonia - Diagnosis

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Pneumonia - Treatment

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Pneumonia - Progression and Prognosis

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Pneumonia Risk Factors

You are more likely to get pneumonia if you:

  • Smoke. Cigarette smoking is the strongest risk factor for pneumonia in healthy young people.
  • Have another medical condition, especially lung diseases such as chronic obstructive pulmonary disease (COPD) or asthma.
  • Are younger than 1 year of age or older than 65.
  • Have an impaired immune system.
  • Take medicine called a proton pump inhibitor (such as Prilosec or Protonix) that reduces the amount of stomach acid.
  • Drink excessive amounts of alcohol.
  • Recently had a cold or the flu.


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