The treatment of choice for lung abscesses is conservative medical management, with the length of therapy dictated by the patient's clinical course and documented radiographic improvement. Radiographic resolution of an abscess cavity may take up to 2 months. Current first-line therapy for lung abscess is antibiotic therapy directed at anaerobes or mixed aerobic and anaerobic bacteria. This is effective in 80 to 90 percent of patients. 15
In earlier studies, most patients with lung abscess responded to oral or parenteral doses of penicillin or tetracycline. 11 However, over the past two decades several strains of anaerobic bacteria have evolved resistance to penicillin and tetracycline. Although penicillin has long been the antibiotic of choice, recent trials show clindamycin to be superior.11 Clindamycin should now be considered the first-choice therapy for anaerobic lung abscess unless otherwise specified by culture results. The adult dosage for clindamycin is 60o mg IV every 6 to 8 h until a clinical response is achieved. Oral clindamycin 300 mg tid or qid can be started once an initial clinical response is noted. Depending on the microbiologic characteristics of the specimens obtained, other antibiotics, such as aminoglycosides, imipenem, chloramphenicol, antipseudomonal penicillins, and cefoxitin, may be effective.
Patients who display no radiographic improvement, show signs of persistent sepsis, or develop complications, such as hemoptysis, bronchopleural fistula, and empyema, require external drainage or resection.15 The incidence of operative management of lung abscesses has decreased dramatically over the last 40 years and is now less than 10 percent.11
Most lung abscesses communicate with the tracheobronchial tree fairly early in the course of the infection and drain spontaneously. Unfavorable conditions, such as a large cavity (greater than 6 cm), necrotizing pneumonia with multiple small abscesses, an elderly or immunocompromised patient, an associated bronchial obstruction, or aerobic bacterial pneumonia may require surgical management despite adequate medical therapy.11 External drainage or resection of a lung abscess is indicated if fever and toxicity persist despite adequate antibiotic therapy and internal drainage. External drainage is the preferred method of treatment for pleural-based abscesses, particularly in patients with a high risk of surgical mortality. 15
Overall, surgical and image-guided percutaneous drainage has been successfully used for treatment of lung abscesses. The patient must be placed in a gravity-dependent position whenever possible in order to avoid soiling the normal lung. Placement of a relatively large-bore catheter (12-French or greater outer diameter) is essential in establishing adequate external drainage and maintaining catheter patency. The catheter is positioned in the abscess cavity, aspirated manually, and subsequently irrigated with saline solution.15 The drainage catheter is irrigated daily in order to maintain patency and placed at -20 cm of water suction.
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