BRONCHIECTASIS & LUNG ABSCESS
Lung Abscess
LUNG ABSCESS • A localized area of destruction of lung parenchyma in which infection by pyogenic organisms results in tissue necrosis & suppuration. • Lung abscess formation usually reflects infection with an unusual microbial burden (e. g. , acute aspiration), an especially virulent organism (e. g. , Staphylococcus aureus), and/or a failure in microbial clearance mechanisms (e. g. , bronchial obstruction)
ETIOLOGY 1. Aspiration (unconsciousness, alcoholism, seizure, general anesthesia, cerebrovascular accident, drug addiction, dysphagia, GERD, and mechanical interference with the cardiac sphincter such as caused by nasogastric tubes and endotracheal intubation). 2. Periodontal disease, gingivitis, sinus infection. 3. Septic pulmonary embolism, most commonly with S. aureus and most commonly in intravenous drug user
ETIOLOGY 4. Any necrotizing pneumonia can also present with areas of abscess, which are commonly small and multiple. 5. Bronchial obstruction. 6. Immunocompromising conditions: diabetes, malignancy, and other.
PATHOGENESIS (STAGES OF PLEUROPULMONARY INFECTION) 1. Pneumonitis (the initial stage) 2. Necrotizing pneumonia (multiple cavities < 2 cm in diameter) 3. Lung abscess 4. Empyema Typical locations of abscesses: üposterior segments of the upper lobes üsuperior segments of the lower lobes.
CLINICAL MANIFESTATIONS I. Initial phase (formation of abscess) Symptoms progress over weeks to months: 1. Fever, night sweats 2. Cough and sputum production 3. Weight loss & anemia 4. Chest pain, dyspnea 5. Hemoptysis, pleurisy
CLINICAL MANIFESTATIONS I. Initial phase (formation of abscess) Physical signs include: ▫ Dullness to percussion ▫ Diminished breath sounds if abscess is large and situated near the surface of lung ▫ Dry rales or fine moist rales – not often
CLINICAL MANIFESTATIONS II. Phase of abscess drainage into the bronchus Symptoms: • Cough with production of purulent foul smell sputum • Fetor Physical signs: • Amphoric/cavernous breath sounds • Coarse moist (large bubbling) rales
DIAGNOSIS • X-ray: cavity with an air-fluid level and surrounding infiltrate. • CT can readily distinguish between lung abscess and an air-fluid level in an empyema cavity.
Lung abcess
Lung abcess
DIAGNOSIS • SPUTUM CULTURE: anaerobic flora (60%), mixed flora (40%) • BLOOD CULTURE • CBC: leukocytosis + shift to the left, anemia • Hypoalbuminemia, dysproteinemia (↑α 2 globulins and γ-globulins, decrease of albuminglobulin coefficient) • TRANSTRACHEAL ASPIRATION
TREATMENT üAntimicrobial therapy and drainage are the most important components of treatment. üPeriods of 1 to 3 months or more may be required
TREATMENT • Clindamycin 600 mg IV every 6 to 8 hours is the drug of choice • The primary alternative is a combination of β-lactam/βlactamase inhibitor: ▫ ampicillin/sulbactam 1 to 2 g IV every 6 h ▫ ticarcillin/clavulanate 3 to 6 g IV every 6 h ▫ piperacillin/tazobactam 3 g IV every 6 h • Metronidazole 500 mg every 8 h may be used but must be combined with penicillin 2 million units every 6 h IV. • Less seriously ill patients may be given oral antibiotics such as clindamycin 300 mg per os every 6 h or amoxicillin/clavulanate 875/125 mg per os every 12 h.
TREATMENT • Postural drainage • Bronchoscopy may help in effecting good drainage, removal of foreign bodies, and diagnosis of tumor. • When surgery is necessary, lobectomy is the most common procedure; segmental resection may suffice for small lesions (< 6 cm diameter cavity). Pneumonectomy may be necessary for multiple abscesses or for pulmonary gangrene unresponsive to drug therapy. • In patients who are poor surgical risks, percutaneous drainage via catheters may be useful.
COMPLICATIONS OF LUNG ABSCESS 1. Empyema 2. Bronchopleural fistula 3. Pneumothorax, pyopneumothorax 4. Metastatic cerebral abscess 5. Sepsis 6. Fibrosis, bronchiectasis, amyloidosis
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