Pneumonia Facts (cont.)
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Charles Patrick Davis, MD, PhD
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
In this Article
- Pneumonia facts
- What is pneumonia?
- What are the different types of pneumonia?
- What causes pneumonia? Is pneumonia contagious?
- What are risk factors for pneumonia?
- What are pneumonia symptoms and signs?
- How do doctors diagnose pneumonia?
- What is the treatment for pneumonia?
- What are complications of pneumonia?
- What is the prognosis of pneumonia?
- Is it possible to prevent pneumonia? Is there a pneumonia vaccine?
- Pneumonia FAQs
- Find a local Internist in your town
What is pneumonia?
Pneumonia is an inflammation of the airspaces in the lung most commonly caused by infections. Bacteria, viruses, or fungi can cause the infection. There are also a few noninfectious types of pneumonia that are caused by inhaling or aspirating foreign matter or toxic substances into the lungs. Around 50,000 people die each year of pneumonia in the U.S. Although anyone of any age can be affected, pneumonia is more common in elderly people and often occurs when the immune system becomes weakened via a prior infection or another condition.
Pneumonia is generally more serious when it affects older adults, infants and young children, those with chronic medical conditions, or those with weakened immune function.
What are the different types of pneumonia?
Pneumonia can be classified in different ways. Doctors often refer to pneumonia based upon the way that the infection is acquired, such as community-acquired pneumonia or hospital-acquired pneumonia.
- Community-acquired pneumonia (CAP), as the name implies, develops outside of the hospital or health-care environment. It is more common than hospital-acquired pneumonia. CAP is most common in winter and affects about 4 million people a year in the U.S.
- Hospital-acquired pneumonia (HAP) is acquired when an individual is already hospitalized for another condition. HAP is generally more serious because it develops in ill patients already hospitalized. Being on a ventilator for respiratory support increases the risk of acquiring HAP.
Other classification systems for pneumonia describe the way the inflammatory cells infiltrate the lung tissue or the appearance of the affected tissue (see the following examples).
- Bronchopneumonia causes scattered, patchy infiltrates of inflammation in the air sacs throughout the lungs. It is more diffuse than lobar pneumonia.
- Lobar pneumonia causes an inflammation of one lobe of a lung and typically involves all the airspaces in a single lobe.
- Lipoid pneumonia is characterized by the accumulation of fats within the airspaces. It can be caused by aspiration of oils or associated with airway obstruction.
Sometimes, types of pneumonia are referred to by the type of organism that causes the inflammation, such as bacterial pneumonia, viral pneumonia, or fungal pneumonia. The specific organism name may also be used to describe the types of pneumonia, such as pneumococcal (Streptococcus pneumoniae) pneumonia or Legionella pneumonia.
Other types of pneumonia that are commonly referenced include the following:
- Aspiration pneumonia develops as a result of inhaling food or drink, saliva, or vomit into the lungs. This occurs when the swallowing reflex is impaired, such as with brain injury or in an intoxicated person.
- Several types of bacteria, including Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydophila pneumoniae, cause atypical pneumonia. It is sometimes called "walking pneumonia" and is referred to as atypical because its symptoms differ from those of other types of bacterial pneumonia.
- Pneumonia that arises from being on a ventilator for respiratory support in the intensive-care setting is known as ventilator-associated pneumonia.
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