[Management of Lung Abscess]

A lung abscess is an infectious pulmonary disease characterised by the presence of a pus-filled cavity within the lung parenchyma. The content of an abscess often drains into the airways spontaneously, leading to an air-fluid level visible on chest X-rays and CT scans. Primary lung abscesses occur in patients who are prone to aspiration or in otherwise healthy individuals; secondary lung abscesses typically develop in association with a stenosing lung neoplasm or a systemic disease that compromises immune defences, such as AIDS, or after organ transplantation. The organisms found in abscesses caused by aspiration pneumonia reflect the resident flora of the oropharynx. The most commonly isolated organisms are anaerobic bacteria (Prevotella, Bacteroides, Fusobacterium, Peptostreptococcus) or streptococci; in alcoholics with poor oral hygiene, the spectrum of pathogens includes Staphylococcus aureus, Streptococcus pyogenes and Actinomyces. Chest radiography and computed tomography (CT) are mandatory procedures in the diagnostic algorithm. Standard treatment for a lung abscess consists of systemic antibiotic therapy, which is based on the anticipated or proven bacterial spectrum of the abscess. In most cases, primary abscesses are successfully treated by calculated empiric antibiotic therapy, with an estimated lethality rate of less than 10 %. Secondary abscesses, despite targeted antimicrobial therapy, are associated with a poor prognosis, which depends on the patient's general condition and underlying disease; lethality is as high as 75 %. Negative prognostic factors are old age, severe comorbidities, immunosuppression, bronchial obstruction, and neoplasms. Surgical intervention due to failure of conservative treatment is required in only 10 % of patients, with a success rate of up to 90 % and postoperative mortality rates ranging between 0 and 33 %. Treatment success after endoscopic or percutaneous drainage is achieved in 73 to 100 % of cases, with an acceptable mortality rate (0-9 %).