(Community-Acquired Pneumonia; CAP; Pneumonitis; Bronchopneumonia)
Pronounced: Noo-MO-NEE-yahEn Español (Spanish Version)More InDepth Information on This Condition
Pneumonia is an infection of the lungs. There are several different organisms that may cause it.
Development of Pneumonia in the Air Sacs of the Lungs
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Pneumonia affects the lower respiratory tract (small bronchi and air sacs in the lungs). There are three main causes:
- Bacterial pneumonia—caused by bacteria, most commonly Streptococcus pneumoniae
Viral pneumonia—caused by a virus
- Viruses cause half of all pneumonias.
- Atypical bacterial pneumonia
—caused by mycoplasmas, chlamydias, or other tiny infectious agents that have traits of both bacteria and viruses
- This type of pneumonia, often called "walking pneumonia," is thought of as a milder pneumonia. However, each of these infectious agents has the potential to cause a more serious or potentially fatal pneumonia.
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 etc.)
Nosocomial pneumonia—acquired during a hospitalization
- It can be very dangerous, especially for patients on a ventilator.
- Aspiration pneumonia —happens when a foreign matter (often stomach content) is inhaled
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A risk factor is something that increases your chance of getting a disease or condition.
Risk factors include:
- Age: 65 or older
- Flu or other respiratory illness
- Chronic illness, such as heart or lung disease
- Stroke (aspiration pneumonia due to difficult swallowing)
- Weakened immune system caused by AIDS or chemotherapy treatment
- Chronic bronchitis
- Infants and very young children
- Alcohol or drug abuse
- Chronic exposure to certain chemicals (eg, work in construction or agriculture)
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, and perform a physical exam. Diagnosis is based on symptoms and listening to your chest with a stethoscope. 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 medicine exactly as prescribed. Stopping medicine midway may cause a relapse, or create a strain of bacteria resistant to drug treatment.
Certain vaccines may prevent pneumonia:
Flu shot —for people at high risk, particularly the elderly, because pneumonia may be a complication of the flu
Other preventive measures include :
- Avoid smoking. Smoking weakens the lungs' resistance to infection.
- Avoid close contact with people who have respiratory infections.
- Wash hands often when coming in contact with infected people.
- Protect yourself from exposures on the job 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 March 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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