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 causes pneumonia?

Streptococcus pneumoniae, a type of bacteria, is the most common cause of pneumonia. Legionella pneumophila is the bacterial type that causes the pneumonia known as Legionnaires' disease. Other bacteria types that can cause pneumonia include the bacteria that cause so-called "atypical" pneumonia, Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydophila pneumonia.

The most common cause of viral pneumonia in adults is the influenza virus. A number of different respiratory viruses cause pneumonia in children, such as respiratory syncytial virus (RSV). While viral pneumonia tends to be less severe than bacterial pneumonia, there is a risk of developing secondary bacterial pneumonia when viral pneumonia is present. Other virus types that can cause pneumonia include measles and varicella (chickenpox) viruses. Rarely, certain viruses may develop lethal pneumonias such as SARS (severe acute respiratory syndrome) or MERS (Middle East respiratory syndrome); both diseases are caused by different coronaviruses.

Fungi that cause pneumonia include Cryptococcus, Histoplasma, and Coccidioides. In most cases, these organisms don't cause illness, but they can cause pneumonia in some people. Fungal infections are most common in those with weakened immune systems due to HIV/AIDS or those taking medications that suppress immune function. Another infection that is considered a fungal type of pneumonia is Pneumocystis jiroveci, formerly known as Pneumocystis carinii. This organism became known as a frequent cause of pneumonia in patients with HIV/AIDS. 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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