Expectorated sputum is not appropriate because the mouth normally contains anaerobic organisms that contaminate the specimen during passage through the upper airways. The attribution of disease to anaerobes usually requires a specimen obtained by transtracheal aspiration, transthoracic aspiration, or fiberoptic bronchoscopy with a protected brush and quantitative cultures, but these procedures are not performed often. Bronchoscopy is unnecessary if response to antibiotics is adequate and if a foreign body or tumor is not suspected. Repeated clinical evaluation and the procedures described above can usually differentiate these disorders from simple lung abscess. Prognosis and Treatment Prompt, complete healing of a lung abscess depends on adequate antibiotic treatment.
Most patients recover without surgery.
Antibiotics should be started as soon as sputum and blood have been collected for culture and sensitivity. The preferred drug is clindamycin, initially 600 mg IV tid, then 300 mg po qid. 500 to 750 mg qid. Antibiotics are changed to oral when the patient is afebrile and subjectively improved. Some authorities prefer to combine penicillin with oral metronidazole 500 mg qid.