History and exam
Key diagnostic factors
common
positive past medical history
Preceding pneumonia is reported in 17% to 40% of lung abscess cases.[8][15]
Aspiration of gastric contents can occur with conditions affecting the neurologic system (alcoholic stupor, seizures, stroke, bulbar dysfunction, general anesthesia) and esophageal disease (stricture, malignancy, reflux, diverticulum). Aspiration of oropharyngeal fluid can occur following dental and oropharyngeal surgery, and nasogastric and endotracheal tube insertion.
Gingival disease, poor dental hygiene, and tooth extraction promote high densities of oral anaerobic organisms.
Bronchial obstruction due to carcinoma, a foreign body, or extrinsic compression from enlarged lymph nodes impairs effective clearing of aspirated secretions and predisposes to infection distal to the site of obstruction.
Metastatic lung abscess may result from septic pulmonary emboli from a site of extrapulmonary infection (e.g., right-sided bacterial endocarditis, septic thrombophlebitis).
Immunosuppression due to chemotherapy, organ transplantation, corticosteroid therapy, or HIV infection, and some chronic diseases (e.g., COPD, bronchiectasis, diabetes mellitus, scleroderma, liver and kidney disease) are also major risk factors for the development of lung abscess.
fever
Acute onset of high fever (e.g., >101°F [>38.5°C]) in acute infection. In chronic infections, low-grade fever may be present for several weeks or longer.
productive cough
Usually productive of purulent sputum. Large amounts of purulent secretions are expectorated in the second or third week. Putrid sputum is present in about 50% of patients. This foul-smelling sputum is highly suggestive of an anaerobic infection.[2]
uncommon
cavernous (amphoric) breath sounds
May be heard over an abscess and resemble the sound made by blowing over the mouth of a bottle.
Other diagnostic factors
common
cardiac murmur
New or worsening cardiac murmurs are signs of bacterial endocarditis, which may cause lung abscess through septic embolism.
pleuritic chest pain
Acute symptom of lung abscess. Symptom of pulmonary embolism that precedes development of persistent fever in lung abscess secondary to infection of a pulmonary infarct.
constitutional symptoms
Night sweats, malaise, and weight loss are common in chronic abscess.
cachexia
In chronic abscess, poor nutritional state may be evident with cachexia and pallor (skin and subconjunctival).
pallor
In chronic abscess, poor nutritional state may be evident with cachexia and pallor (skin and subconjunctival) secondary to anemia of chronic disease.
gingival disease
Signs of gingival disease with associated halitosis may be present.
halitosis
Signs of gingival disease with associated halitosis may be present.
absence of gag reflex
May be absent in patients with an underlying neurologic disorder such as stroke.
uncommon
dyspnea
Symptom of pulmonary embolism that precedes development of persistent fever in lung abscess secondary to infection of a pulmonary infarct.
hemoptysis
May be present in chronic lung abscess and is usually minor, although can be massive.[25]
Symptom of pulmonary embolism that precedes development of persistent fever in lung abscess secondary to infection of a pulmonary infarct.
rigors
Although almost never reported, chills and rigors may be present in patients with lung abscess secondary to septic embolism from right-sided (e.g., tricuspid valve) bacterial endocarditis or septic thrombophlebitis due to bacteremia.
weakness
Nonspecific symptom of bacterial endocarditis, which may cause lung abscess through septic embolism.
arthralgia
Symptom of bacterial endocarditis, which may cause lung abscess through septic embolism.
hemorrhagic lesions
Lesions of skin and retina are signs of bacterial endocarditis, which may cause lung abscess through septic embolism.
inspiratory crackles
Heard in the presence of associated parenchymal consolidation.
bronchial breathing
Heard in the presence of associated parenchymal consolidation.
decreased breath sounds
Heard in the presence of associated empyema.
unilateral fixed rhonchus
Fixed rhonchus limited to 1 hemithorax indicates an airway obstruction, which may be due to a tumor or foreign body.
Risk factors
strong
predisposition to aspiration of gastric contents
Depressed consciousness and a suppressed gag reflex predispose to gastric content aspiration and are thus major risk factors for developing lung abscess.[4][8][15][22][23] Aspiration can result from alcoholic stupor, seizures, stroke, neurologic bulbar dysfunction, drug overdose, general anesthesia, dental or oropharyngeal surgery, esophageal disease (stricture, malignancy, reflux and diverticulum), and nasogastric or endotracheal tubes.
poor dental hygiene and tooth extraction
Gingival disease and poor dental hygiene are common, and they promote high densities of oral anaerobic organisms, particularly in the gingival crevices. By contrast, anaerobic lung abscesses are rare in edentulous patients. Tooth extraction is also a risk factor.
bronchial obstruction
Carcinoma, foreign body, or extrinsic compression from enlarged lymph nodes can cause obstruction that impairs effective clearing of aspirated secretions. Predisposes to infection distal to the site of obstruction.
immunosuppression
chronic illness
extrapulmonary sepsis
pneumonia
Preceding pneumonia is common and usually results in a monomicrobial abscess caused by aerobic bacteria (e.g., Staphylococcus aureus, Klebsiella pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, Escherichia coli, Pasteurella multocida, Burkholderia, Legionella species, Streptococcus pneumoniae, and group A streptococci).[8][15] Underlying pneumonia is also associated with increased mortality.
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