What causes aspiration pneumonia?

Updated: Aug 15, 2018
  • Author: Justina Gamache, MD; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
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Answer

Answer

This article concentrates on chemical pneumonitis and aspiration pneumonia.

Aspiration pneumonia is caused by bacteria that normally reside in the oral and nasal pharynx. Historically, aspiration pneumonia referred to an infection caused by less virulent bacteria, primarily oral pharyngeal anaerobes, after a large volume aspiration event. It is now recognized that many common community-acquired and hospital-acquired pneumonias result from small-volume aspiration of more virulent pathogens from the oral cavity or nasopharynx, such as Streptococcus pneumoniae,Haemophilus influenza, Staphylococcus aureus, and gram-negative bacteria.

For patient education information, see the Infections Center, as well as Chemical Pneumonia, Bacterial Pneumonia and Bronchoscopy.

For more information, see the following:

The images below depict aspiration pneumonia in two different patients.

Aspiration pneumonia in an 84-year-old man in gene Aspiration pneumonia in an 84-year-old man in generally good health who had fever and cough. This posteroanterior radiograph demonstrates a left lower lobe opacity.
Chest radiograph of a patient with aspiration pneu Chest radiograph of a patient with aspiration pneumonia of the left lung after a benzodiazepine overdose. The patient was probably positioned to the left at the moment of aspiration

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