Management of bacterial lung abscess in adults

Most lung abscesses result from aspiration and are polymicrobial, composed of oral flora (eg, microaerophilic streptococci and anaerobes, such as Peptostreptococcus, Prevotella, Bacteroides, and Fusobacterium spp). Less commonly, lung abscesses arise from complications of pneumonia caused by pyogenic bacteria (eg, Klebsiella pneumoniae, Staphylococcus aureus), from direct extension (eg, traumatic inoculation), or endobronchial obstruction. The majority of lung abscesses can be treated with antibiotic therapy alone. Empiric antibiotic selection varies based on the suspected route and suspected pathogen. For most lung abscesses that result from aspiration, a regimen that targets oral flora is appropriate (refer to Inset). Modifications to the regimen may be needed when drug-resistant or other less common pathogens are suspected. Refer to UpToDate topic on lung abscess for details.