Thoracic empyema requires prompt and effective drainage combined with appropriate antibiotics. The clinical circumstances resulting in development of an empyema may give a clue to the infecting organism, although microbiological examination of the pleural fluid can assist in the choice of antibiotic therapy. In the majority of cases, infection of the plural space is associated with a pneumonia or lung abscess. Inhalation of oropharyngeal secretions can play an important role: this occurs if there is bulbar dysfunction or vomiting, especially associated with loss of consciousness. Bronchial obstruction due to carcinoma or an inhaled foreign body may also predispose to secondary infection. Other sources of infection include penetrating chest injury or direct spread fropm subdiaphragmatic infection.

Although Streptococcus pneumoniae remains a major cause, especially when viewed in a global setting, anaerobic organisms are isolated from a significant proportion of empyemas. The spectrum of infecting agents most frequently encountered in the United Kingdom is listed in Table 1 542. Multiple isolates, often mixed anaerobes, occur in approximately 25 per cent of cases.

The initial choice of antibiotic has to be made without micro-biological guidance; this needs to be revised on the basis of the clinical response and subsequent laboratory identification of infecting organisms. Ampicillin or cefuroxime will eliminate the more common aerobic organisms and can be combined with metronidazole if infection by anaerobes is suspected. If a staphylococcal infection seems likely, flucloxacillin is an appropriate choice. Antibiotics penetrate the pleural space well and intra-pleural instillation is unnecessary. The duration of treatment depends on clinical response but 14 days is usually adequate, providing the patient has made a good clinical response and there is no reaccumulation of pleural fluid.

Antibiotic treatment alone is ineffective and it must therefore be combined with pleural drainage. There is no clear consensus as to the best approach: both needle aspiration and intercostal tube drainage can be effective. Repeated aspiration through a wide bore needle can be used, especially if loculated collections of fluid can be identified with ultrasound guidance. An alternative and more conventional approach involves the insertion of a large intercostal tube. Positioning of the tube is important: ultrasound or fluoroscopy is helpful. The tube can be removed once drainage has ceased, although clinical or radiological evidence of residual fluid is an indication for reinsertion. If the pus is very viscid, and loculated collections prove difficult to drain, surgical intervention with decortication may be necessary.

Delikari PG, Conlan AA, Abramer E, Hurnitz SS, Studi R. Empyema thoracis—a prospective study on 73 patients. S Afr Med J 1984; 65: 47–9.

Varkey B, Rose HD, Cully CPK, Politis J. Empyema thoracis during a 10 year period: analysis of 72 cases in comparison to a previous study (1952–1967). Arch Intern Med 1981; 141: 1171–6.