Definition

Pneumonia is an infection that affects the small airways and air sacs in the lungs.

Pneumonia is sometimes described by where and how you were infected. Types of pneumonia include:

• Community-acquired—from the community, such as a school, gym, or at work
• Nosocomial—in a hospital or healthcare setting
• Aspiration—happens when foreign matter is inhaled into the lungs, such as food, liquid, saliva, or vomit

Causes

Pneumonia may be caused by:

• Infection from specific types of:
  • Bacteria
  • Viruses
  • Fungi
• Aspiration
• Other specific germs
• Chemical exposure and irritation

Risk Factors

Pneumonia is more common in older adults. Other factors that may increase your chance of pneumonia include:

• Living in crowded living conditions, such as dormitories or nursing homes
• Smoking
• Alcohol use disorder or drug abuse
• Trouble swallowing or coughing
• Having certain lung conditions, such as chronic obstructive pulmonary disease (COPD) or cystic fibrosis
• Allergies or asthma
• Sleep apnea
• Being on a ventilator
• Heart disease
• Diabetes
• Weakened immune system
• Malnutrition
• Exposures to respiratory inhalants at work, such as:
  • Ammonia
  • Chlorine
  • Minerals
  • Vegetable dusts

Symptoms

Pneumonia may cause:

• Cough
• Chest pain
• Increased mucus production
• Fever and chills
• Trouble breathing
• Weakness

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. Your doctor may suspect pneumonia based on your symptoms, and breath and lung sounds. Tests can confirm diagnosis and determine the specific germ causing the pneumonia.

Your bodily fluids may be tested with:

• Blood tests and/or cultures
• Sputum culture
• Urine tests

Pulse oximetry measures blood oxygen levels.

Images may be taken of your lungs. This can be done with:

• A chest x-ray
• A lung ultrasound

Treatment

Treatment of pneumonia depends on:

• What caused the pneumonia
• Severity of symptoms
• Other factors, like your overall health

People with severe pneumonia may need to be hospitalized.

Prevention

Certain vaccines may prevent pneumonia:

• Flu vaccine—pneumonia may be a complication of the flu for people at high risk of infection, especially aged 50 years and older
• Pneumococcal vaccine:
  • All adults who are aged 65 years or older
  • Adults of any age who are at high risk of infection or have a suppressed immune system

Other preventive measures include:

• If you smoke, talk to your doctor about how you can successfully quit. Smoke weakens the lungs’ resistance to infection and increases recovery time.
• Avoid close contact with people who have the cold or flu.
• Wash your hands often, especially after coming into contact with someone who is sick..
• Protect yourself on jobs that include chemicals or other lung irritants.
• Maintain good control of any chronic disease, such as asthma and diabetes.

Family Doctor—American Academy of Family Physicians http://www.familydoctor.org

The Lung Association http://www.lung.ca

Blasi F, Aliberti S, et al. 100 years of respiratory medicine: Pneumonia. Respir Med. 2007;101(5):875-881.

Braunwald E, Harrison TR, et al. Harrison’s Principles of Internal Medicine. 17th ed. Columbus, OH: McGraw-Hill; 2008.

Carpenter CC, Andreoli TE, et al. Cecil Essentials of Medicine. Philadelphia, PA: Elsevier Science; 2003.

Community-acquired pneumonia in adults. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed
Updated December 5, 2014. Accessed February 18, 2014.

De Roux A, Marcos MA, et al. Viral community-acquired pneumonia in non-immunocompromised adults. Chest. 2004;125(4):1343-1351.

Explore pneumonia. National Heart Lung Blood Institute (NHLBI) website. Available at:
http://www.nhlbi.nih.gov/health/health-topics/topics/pnu
Updated March 1, 2011. Accessed February 18, 2015.

Niederman MS. Recent advances in community-acquired pneumonia inpatient and outpatient. Chest. 2007;4:1205-1215.

Niederman MS. Review of treatment guidelines for community-acquired pneumonia. Am J Med. 2004;117:Suppl 3A:51S-57S.

10/29/2009 DynaMed Systematic Literature Surveillance
http://www.ebscohost.com/dynamed:
Hemila H, Louhiala P. Vitamin C for preventing and treating pneumonia. Cochrane Database Syst Rev. 2009;(3):CD005532.

10/21/2013 DynaMed’s Systematic Literature Surveillance
http://www.ebscohost.com/dynamed:
Hemilä H, Louhiala P. Vitamin C for preventing and treating pneumonia. Cochrane Database Syst Rev. 2013;8:CD005532.

3/10/2014 DynaMed’s Systematic Literature Surveillance
http://www.ebscohost.com/dynamed:
Su VY, Liu CJ, et al. Sleep apnea and risk of pneumonia: A nationwide population-based study. CMAJ. 2014;186(6):415-421.

6/17/2014 DynaMed’s Systematic Literature Surveillance
http://www.ebscohost.com/dynamed:
Reissig A, Copetti R, et al. Lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia: A prospective, multicenter diagnostic accuracy study. Chest. 2012;142(4):965-972.

2/3/2015 DynaMed’s Systematic Literature Surveillance
http://www.ebscohost.com/dynamed:
Rantala A, Jaakkola JJ, et al. Respiratory infections in adults with atopic disease and IgE antibodies to common aeroallergens. PLoS One. 2013;8(7):e68582.