Pneumonia is an infection of the lungs. Many different organisms can cause it, including bacteria, viruses, and fungi.
Pneumonia can range from mild to severe, and can even be deadly. The severity depends on the type of organism causing pneumonia, as well as your age and underlying health.
Pneumonia is a common illness that affects millions of people each year in the United States.
Bacterial pneumonias tend to be the most serious and, in adults, the most common cause of pneumonia. The most common pneumonia-causing bacterium in adults is Streptococcus pneumoniae (pneumococcus).
Respiratory viruses are the most common causes of pneumonia in young children, peaking between the ages of 2 and 3. By school age, the bacterium Mycoplasma pneumoniae becomes more common.
In some people, particularly the elderly and those who are debilitated, bacterial pneumonia may follow influenza or even a common cold.
People who have trouble swallowing are at risk of aspiration pneumonia. In this condition, food, liquid, or saliva accidentally goes into the airways. It is more common in people who have had a stroke, Parkinson's disease, or previous throat surgery.
It is often harder to treat pneumonia in people who are in a hospital, or a nursing facility.
Viral pneumonia (2 images)(Doctor-Reviewed information)
Viral pneumonia is an inflammation(irritation and swelling) of the lungs caused by infection with a virus.Reviewer: Benjamin Medoff, MD, Assistant Professor of Medicine, Harvard Medical School, Pulmonary and Critical Care Unit, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 09/24/2008
Atypical pneumonia (2 images)(Doctor-Reviewed information)
Atypical pneumonia refers to pneumonia caused by certain bacteria, including Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydophila pneumoniae.This article provides a general overview of atypical pneumonia.Reviewer: Benjamin Medoff, MD, Assistant Professor of Medicine, Harvard Medical School, Pulmonary and Critical Care Unit, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 09/24/2008
CMV - pneumonia (2 images)(Doctor-Reviewed information)
Cytomegalovirus(CMV) pneumonia is an infection of the lungs that can occur in people who have a suppressed immune system.Pneumonia- cytomegalovirus; Cytomegalovirus pneumonia; Troll of transplantation.CMV pneumonia is caused by a member of a group...Reviewer: Kenneth M. Wener, M.D., Department of Infectious Diseases, Lahey Clinic, Burlington, MA. Review provided by VeriMed Healthcare Network.Date: 11/01/2007
Psittacosis (2 images)(Doctor-Reviewed information)
Psittacosis is an infection caused by Chlamydia psittaci, a type of bacteria found in the droppings of birds. Birds spread the infection to humans.Psittacosis is a rare disease-- 100 to 200 cases are reported each year in the United States.Bird ow...Reviewer: Sean O. Stitham, MD, private practice in Internal Medicine, Seattle, Washington; and Benjamin Medoff, MD, Assistant Professor of Medicine, Harvard Medical School, Pulmonary and Critical Care Unit, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 08/29/2008
Legionnaire's disease (1 image)(Doctor-Reviewed information)
Legionnaire''s disease is an acute respiratory infection caused by Legionella bacteria.The bacteria that cause Legionnaire''s disease have been found in water delivery systems. They can survive in the warm, moist, air conditioning systems of large b...Reviewer: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 03/17/2009
Mycoplasma pneumonia (6 images)(Doctor-Reviewed information)
Mycoplasma pneumonia is an infection of the lungs caused by by the bacteria Mycoplasma pneumoniae(M. pneumoniae).Mycoplasma pneumonia is a type of atypical pneumonia. It is caused by the bacteria M. pneumoniae. Reviewer: Benjamin Medoff, MD, Assistant Professor of Medicine, Harvard Medical School, Pulmonary and Critical Care Unit, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 09/24/2008
Hospital-acquired pneumonia (2 images)(Doctor-Reviewed information)
Hospital-acquired pneumonia is an infection of the lungs contracted during a hospital stay.Nosocomial pneumonia; Ventilator-associated pneumonia.Pneumonia is a very common illness. It is caused by many different germs and can range in seriousness ...Reviewer: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 03/17/2009
Aspiration pneumonia (4 images)(Doctor-Reviewed information)
Aspiration pneumonia is inflammation of the lungs and airways to the lungs(bronchial tubes) from breathing in foreign material.Anaerobic pneumonia; Aspiration of vomitus; Necrotizing pneumonia; Aspiration pneumonitis; Chemical pneumonitis.Aspirati...Reviewer: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 03/17/2009
Pneumocystis carinii pneumonia (3 images)(Doctor-Reviewed information)
Pneumocystis carinii pneumonia(PCP) is a fungal infection of the lungs.PCP is a pneumonia caused by the fungal organism Pneumocystis carinii( now renamed Pneumocystis jiroveci). This organism is common in the environment and does not cause illness...Reviewer: Kenneth M. Wener, M.D., Department of Infectious Diseases, Lahey Clinic, Burlington, MA. Review provided by VeriMed Healthcare Network.Date: 11/01/2007
Pneumonia - weakened immune system (4 images)(Doctor-Reviewed information)
Pneumonia is a lung infection that can be caused by many different germs, including bacteria, viruses, and fungi.This article discusses describes pneumonia that occurs in a person whose ability to fight infection is greatly reduced because their i...Reviewer: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, PhD, MD, Instructor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 06/10/2009
Hydrocarbon pneumonia (1 image)(Doctor-Reviewed information)
Hydrocarbon pneumonia is caused by drinking or breathing in gasoline, kerosene, furniture polish, paint thinner, or other oily materials or solvents. These products cause fairly rapid changes in the lungs, including inflammation, swelling, and ble...Reviewer: John E. Duldner, Jr., MD, MS, Assistant Professor of Emergency Medicine, Department of Emergency Medicine, Samaritan Regional Health System, Ashland, Ohio. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 01/30/2009
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