Pneumonia

  • Medical Author:
    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.

  • Medical Editor: Charles Patrick Davis, MD, PhD
    Charles Patrick Davis, MD, PhD

    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.

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. Health-care-associated pneumonia is acquired from other health-care settings, like dialysis centers, outpatient clinics, or nursing homes.

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. Continue Reading
Reviewed on 4/22/2016
References
REFERENCES:

American Lung Association. "Pneumonia Fact Sheet." <http://www.lung.org/lung-disease/influenza/in-depth-resources/pneumonia-fact-sheet.html>.

"Healthcare-Associated Pneumonia." Medscape.com. <http://www.medscape.org/viewarticle/558518>.

United States. Centers for Disease Control and Prevention. "Pneumonia." Feb. 25, 2015. <http://www.cdc.gov/pneumonia/index.html>.

United States. Centers for Disease Control and Prevention. "Pneumococcal Vaccination: Who Needs It?" June 19, 2015. <http://www.cdc.gov/vaccines/vpd-vac/pneumo/vacc-in-short.htm>.

United States. National Heart, Lung, and Blood Institute. "Types of Pneumonia." Mar. 1, 2011. <http://www.nhlbi.nih.gov/health/health-topics/topics/pnu/types.html>.

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