New aspirations: the debate on aspiration pneumonia treatment guidelines.

Aspiration pneumonia occurs most commonly in patients with a predisposition to aspiration (eg, those with neurological bulbar dysfunction). There is limited evidence regarding the involvement of anaerobes in most cases of aspiration pneumonia. Most patients respond to treatment for aspiration pneumonia without specific anti-anaerobic therapy such as metronidazole. Metronidazole has adverse side effects, and widespread use where not indicated can promote carriage of multiresistant intestinal flora such as vancomycin-resistant enterococci. Use of metronidazole may be appropriate in patients with aspiration pneumonia and evidence of a lung abscess, necrotising pneumonia, putrid sputum or severe periodontal disease.