Pneumonia (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
The normal exchange of gases is interrupted by the build up of fluids.
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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:
Mycoplasmahis Chlamydias Other tiny infectious agents that have traits of both bacteria and viruses
Other causes of pneumonia include:
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
—happens when a foreign matter (often stomach content) is inhaled
Aspiration pneumonia Aspiration
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Factors that increase your chance of pneumonia include:
or other respiratory illness
Chronic illness, such as heart or lung disease
(aspiration pneumonia due to difficult swallowing)
Weakened immune system caused by
chemotherapy Chronic bronchitis Malnutrition Pregnancy Infants and very young children Alcohol or drug abuse Smoking 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 Shaking chills Chills Chills 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:
—a test that uses radiation to take pictures of structures inside the body, in this case the chest
—a type of x-ray that uses a computer to make pictures of structures inside the chest
CT scan Blood tests
—direct examination of airways
Bronchoscopy 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
Certain vaccines may prevent pneumonia:
—for people at high risk, particularly the elderly, because pneumonia may be a complication of the flu
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.
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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
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Last reviewed February 2009 by
Rosalyn Carson-DeWitt, 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
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