Aspiration pneumonia

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Aspiration pneumonia
Aspiration pneumonia (2).jpg
Microscopic image of aspiration pneumonia in an elderly person with a neurologic illness. Note foreign-body giant cell reaction.
Specialty Emergency medicine, pulmonology
Symptoms Fever, cough[1]
Complications Lung abscess[1]
Usual onset Elderly[2]
Risk factors Decreased level of consciousness, problems with swallowing, alcoholism, tube feeding, poor oral health[1]
Diagnostic method Based on presenting history, symptoms, chest X-ray, sputum culture[2][1]
Similar conditions Chemical pneumonitis, tuberculosis[1][2]
Medication Clindamycin, meropenem, ampicillin/sulbactam, moxifloxacin[1]
Frequency ~10% of pneumonia cases requiring hospitalization[1]

Aspiration pneumonia is a type of lung infection that is due to a relatively large amount of material from the stomach or mouth entering the lungs.[1] Symptoms often include fever and cough of relatively rapid onset.[1] Complications may include lung abscess.[1] Some include chemical pneumonitis as a subtype, which occurs from acidic but non-infectious stomach contents entering the lungs, while other do not.[1][2]

Infection can be due to a variety of bacteria.[2] Risk factors include decreased level of consciousness, problems with swallowing, alcoholism, tube feeding, and poor oral health.[1] Diagnosis is typically based on the presenting history, symptoms, chest X-ray, and sputum culture.[1][2] Differentiating from other types of pneumonia may be difficult.[1]

Treatment is typically with antibiotics such as clindamycin, meropenem, ampicillin/sulbactam, or moxifloxacin.[1] For those with only chemical pneumonitis antibiotics are not typically required.[2] Among people hospitalized with pneumonia, about 10% are due to aspiration.[1] It occurs more often in older people, especially those in nursing homes.[2] Both sexes are equally commonly affected.[2]


Aspiration pneumonia is often caused by a defective swallowing mechanism, often due to a neurological disease or as the result of an injury that directly impairs swallowing or interferes with consciousness. Examples of the former are stroke, Parkinson's disease, and multiple sclerosis, and examples of the latter are some types of dementia, seizures, intoxication, and general anaesthesia. For many types of surgical operations, patients are therefore instructed to take nothing by mouth (nil per os, abbreviated as NPO) for at least four hours before surgery.

Risk factors[edit]

  • Ethnicity
    • In the United States, African-Americans are hospitalized at a significantly higher rate than whites for aspiration pneumonia. Asians have a lower risk of death, and the risk of death for African-Americans is not significantly different from whites. Hispanics have a lower risk of death than non-Hispanics.[3]
  • Age, male gender, poor dental hygiene, lung disease, swallowing difficulties, diabetes mellitus, severe dementia, malnutrition, Parkinson's disease, use of antipsychotic drugs, proton pump inhibitors, and angiotensin-converting enzyme inhibitors.[4][5]
  • Reduced functional status, residence in an institutional setting, prolonged hospitalization or surgical procedures, impaired consciousness, chronic swallowing disorders, mechanical airway interventions, immunocompromised, history of smoking, antibiotic therapy, advanced age, reduced pulmonary clearance, diminished cough reflex, disrupted normal mucosal barrier, impaired mucociliary clearance, alter cellular and humoral immunity, obstruction of the airways, and damaged lung tissue.[6]

Whether aspiration pneumonia represents a true bacterial infection or a chemical inflammatory process remains the subject of significant controversy. Both causes may be present with similar symptoms.

Implicated bacteria[edit]

When bacteria are implicated, they are usually aerobic[verification needed]:

They may also be admixed with anaerobic bacteria oral flora:


The location is often gravity dependent, and depends on the patient position. Generally, the right middle and lower lung lobes are the most common sites affected, due to the larger caliber and more vertical orientation of the right mainstem bronchus. Patients who aspirate while standing can have bilateral lower lung lobe infiltrates. The right upper lobe is a common area of consolidation in alcoholics who aspirate in the prone position.[8]


Aspiration pneumonia in a ventilated person with a central line and nasogastric tube

Aspiration pneumonia is typically diagnosed by a combination of clinical circumstances (a debilitated or neurologically impaired person), radiologic findings (an infiltrate in the proper location), and sometimes with the help of microbiologic cultures. Some cases of aspiration pneumonia are caused by aspiration of food particles or other particulate substances like pill fragments; these can be diagnosed by pathologists on lung biopsy specimens.[9]

See also[edit]


  1. ^ a b c d e f g h i j k l m n o p DiBardino, DM; Wunderink, RG (February 2015). "Aspiration pneumonia: a review of modern trends.". Journal of critical care. 30 (1): 40–8. PMID 25129577. doi:10.1016/j.jcrc.2014.07.011. 
  2. ^ a b c d e f g h i Ferri, Fred F. (2017). Ferri's Clinical Advisor 2018 E-Book: 5 Books in 1. Elsevier Health Sciences. p. 1006. ISBN 9780323529570. Archived from the original on 2017-07-31. 
  3. ^ Oliver, N.M., Stukenborg, G.J., Wagner, D.P., Harrell, F.E., Kilbirdge, K.L., Lyman, J.A., Einbinder, J., & Connors, A.F. (2004). Ethnicity on In-Hospital Mortality from Aspiration Pneumonia. Journal of the National Medical Association, 96(11), 1462-1469.
  4. ^ Scannapieco, F.A., Mylotte, J.M. (1996). Relationship between periodontal disease and bacterial pneumonia. Journal of Periodontal, 67, suppl 10, 1114-1122.
  5. ^ van der Maarek-Wierink, C.D., Vanobbergen, J.N., Bronkhorst, E.M., Schols, J.M., & de Baat, C., (2011). Risk factors for aspiration pneumonia in frail older people: a systematic literature review. Journal of American Medical Directors Association, 12(5), 344-354.
  6. ^ Taylor, G.W., Loesche, W.J., & Terpenning, M.S. (2000). Impact of Oral Diseases on Systemic Health in the Elderly: Diabetes Mellitus and Aspiration Pneumonia. Journal of Public Health Dentistry, 60(4), 313-320
  7. ^ a b c d e f g h Table 13-7 in: Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K; Fausto, Nelson. Robbins Basic Pathology: With Student Consult Online Access. Philadelphia: Saunders. ISBN 1-4160-2973-7.  8th edition.
  8. ^ Anand Swaminathan, MD. " Pneumonia, Aspiration". Archived from the original on 2007-01-19.  Retrieved: 2007-01-20
  9. ^ Mukhopadhyay S, Katzenstein AL (2007). "Pulmonary disease due to aspiration of food and other particulate matter: a clinicopathologic study of 59 cases diagnosed on biopsy or resection specimens.". American Journal of Surgical Pathology. 31 (5): 752–759. PMID 17460460. doi:10.1097/01.pas.0000213418.08009.f9. 

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