(Community-Acquired Pneumonia; CAP; Pneumonitis; Bronchopneumonia)
Pneumonia is an infection of the lungs. It affects the lower respiratory tract. This includes small bronchi (airways) and air sacs in the lungs.
Development of Pneumonia in the Air Sacs of the Lungs
There are three main causes:
- Bacterial pneumonia—caused by bacteria, most commonly Streptococcus pneumoniae
- Viral pneumonia—caused by a virus (responsible for half of all pneumonias)
- Atypical bacterial pneumonia
—often called "walking pneumonia but can cause a more serious or potentially fatal pneumonia; caused by:
- Other tiny infectious agents that have traits of both bacteria and viruses
Other causes of pneumonia include:
Fungal infections, such as
Pneumocystis carinii pneumonia(PCP)—a fungal infection common in people with AIDS
Pneumonias are sometimes described by where it was acquired and how you were exposed to it:
- Community-acquired pneumonia—acquired in the community (eg, at school, work, gym)
Nosocomial pneumonia—acquired during a hospitalization
- Can be very dangerous, especially for patients on a ventilator
Aspiration pneumonia—happens when a foreign matter (often stomach content) is inhaled
Factors that increase your chance of pneumonia include:
- Age: 65 or older
Symptoms of pneumonia may include some or all of the following:
|Bacterial Pneumonia||Viral Pneumonia||Atypical Pneumonia|
|Fever||Fever||Fever, often low-grade|
|Cough that produces green, yellow, or rust-colored mucus||Dry cough||Coughing; may be violent at times; produces white mucus|
|Chest pain||Headache||Possible nausea or vomiting|
|Profuse sweating||Muscle pain||Weakness|
|Bluish color of the nails or lips due to diminished oxygen in the blood||Bluish color of the nails or lips due to diminished oxygen in the blood|
|Confused mental state||Weakness|
The doctor will ask about your symptoms and medical history. A physical exam will be done. Diagnosis is based on symptoms and listening to your chest. Tests may include:
- Chest x-ray —a test that uses radiation to take pictures of structures inside the body, in this case the chest
CT scan—a type of x-ray that uses a computer to make pictures of structures inside the chest
- Blood tests
Bronchoscopy—direct examination of airways
- Sputum culture—testing mucus coughed up from deep in the lungs
- Pulse oximetry—measures the amount of oxygen in the blood
- Arterial blood gas—measures oxygen, carbon dioxide, and acid in the blood
Treatment of pneumonia depends on:
- Type of pneumonia
- Severity of symptoms
- Other factors
Common methods of treatment include:
- Rest and fluids
- Antiviral medicines—may be prescribed for young children and patients with weakened immune systems
- Note: Antibiotics are ineffective for treating viral pneumonia
- Over-the-counter medicines to reduce fever and aches, and soothe cough
- Hospitalization, for people with very severe symptoms
It is very important to take the medicine as prescribed. Stopping medicine early may cause a relapse. It may also create a strain of drug resistant bacteria.
If you are diagnosed with pneumonia, follow your doctor's instructions .
Certain vaccines may prevent pneumonia:
- Flu shot —for people at high risk, particularly the elderly, because pneumonia may be a complication of the flu
Pneumococcal vaccine—recommended for:
Other preventive measures include:
- Avoid smoking. Smoke weakens the lungs' resistance to infection.
- Avoid close contact with people who have the cold or flu.
- Wash hands often. This is very important when coming in contact with infected people.
- Protect yourself on jobs that affect the lungs.
- Eat a healthy diet.
- Get adequate rest.
- Exercise regularly.
American Academy of Family Physicians
American Lung Association
The Canadian Lung Association
Blasi F, Aliberti S, Pappalettera M, Tarsia P. 100 years of respiratory medicine: pneumonia. Respir Med . 2007 Mar 21; [Epub ahead of print].
Braunwald E, Harrison TR, Fauci AS, Kasper DL, Hauser SL, Jameson JL, et al. Harrison's Principles of Internal Medicine . 15 th ed. Columbus, OH: McGraw-Hill; 2001.
Carpenter CC, Andreoli TE, Griggs RC. Cecil Essentials of Medicine . Philadelphia, PA: Elsevier Science; 2003.
Fleming CA, Balaguera HU, Craven DE. Risk factors for nosocomial pneumonia. Focus on prophylaxis. Med Clin North Am . 2001 Nov;85(6):1545-63. Review.
Niederman MS. Review of treatment guidelines for community-acquired pneumonia. Am J Med . 2004 Aug 2;117 Suppl 3A:51S-57S. Review.
Last reviewed February 2009 by
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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