Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 9-11: Pneumonia + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ History of or predisposition to aspiration Indolent symptoms, including fever, weight loss, malaise Poor dentition Foul-smelling purulent sputum (in many patients) Opacity in dependent lung zone, with single or multiple areas of cavitation or pleural effusion +++ General Considerations ++ Nocturnal aspiration of small amounts of oropharyngeal secretions is typically not pathologic Larger aspirations may cause Nocturnal asthma Chemical pneumonitis Bronchiectasis Mechanical obstruction Pleuropulmonary infection Predisposing factors include Drug or alcohol use Seizures Anesthesia CNS disease Trachea or nasogastric tubes Periodontal disease and poor oral hygiene are associated with a greater likelihood of pleuropulmonary infection Disease usually occurs in dependent lung zones Most infections include multiple anaerobic bacteria Prevotella melaninogenica Peptostreptococcus Fusobacterium nucleatum Bacteroides + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ Onset is insidious; necrotizing pneumonia, abscess, or empyema may be apparent at presentation Constitutional symptoms of fever, malaise, and weight loss are common Cough with foul-smelling expectorant suggests anaerobic infection Poor dentition is typical; patients are rarely edentulous Occurrence in an edentulous patient suggests an obstructing bronchial lesion +++ Differential Diagnosis ++ Other causes of cavitary lung disease Tuberculosis Fungal infection Bronchogenic cancer Pulmonary infarction Granulomatosis with polyangiitis Cavitary bacterial pneumonia Fungal infection, eg, histoplasmosis Bronchiectasis + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests ++ Culture of expectorated sputum is not useful due to contamination with oral flora +++ Imaging Studies ++ Chest radiograph in a lung abscess shows a thick-walled cavity surrounded by consolidation, occasionally with an air-fluid level Chest radiograph in necrotizing pneumonia demonstrates multiple areas of cavitation within an area of consolidation Empyema is characterized by purulent pleural fluid and may accompany the findings of abscess or necrotizing pneumonia Ultrasonography may identify loculations or help localize fluid for safe thoracentesis +++ Diagnostic Procedures ++ Representative material for culture can be obtained only by Transthoracic aspiration Thoracentesis Bronchoscopy with a protected brush + Treatment Download Section PDF Listen +++ +++ Medications ++ Clindamycin (600 mg every 8 hours intravenously, then 300 mg every 6 hours orally after initial improvement) Amoxicillin-clavulanate (875 mg/125 mg every 12 hours orally) Penicillin (amoxicillin 500 mg every 8 hours orally or penicillin G 1–2 million units every 4–6 hours intravenously) plus metronidazole 500 mg every 8–12 hours orally or intravenously Penicillin alone is inadequate treatment Therapy should be continued until the chest radiograph improves, usually for a month or more +++ Surgery ++ Open pleural drainage is sometimes needed because of loculations associated with a parapneumonic effusion +++ Therapeutic Procedures ++ Thoracentesis Thoracostomy tube drainage for empyema in anaerobic pleuropulmonary infection + Outcome Download Section PDF Listen +++ +++ Follow-Up ++ Monitor with chest radiography; if radiograph does not improve, consider other causes +++ Prevention ++ Good dental hygiene +++ Prognosis ++ Excellent with appropriate antimicrobial therapy +++ When to Refer ++ Refer to infectious disease expert, pulmonary specialist, or thoracic surgeon if no response to antibiotic therapy or concern about the presence of another process (eg, cancer) +++ When to Admit ++ Hypoxemia Severe malnutrition Marked systemic symptoms + References Download Section PDF Listen +++ + +Makhnevich A et al. Aspiration pneumonia in older adults. J Hosp Med. 2019 Jul 1;14(7):429–35. [PubMed: 30794136] + +Rolston KVI et al. Post-obstructive pneumonia in patients with cancer: a review. Infect Dis Ther. 2018 Mar;7(1):29–38. [PubMed: 29392577]