Anaerobic pulmonary infections

Abstract

The main cause of anaerobic pulmonary infections is aspiration of saliva, upper airway secretions or gastric content. Predisposing conditions include prominent dental disease, chronic upper respiratory tract infections and reduced consciousness. Fusobacterium nucleatum, Bacteroides melaninogenicus and anaerobic Gram-positive cocci are the most frequently encountered organisms. The clinical presentations are lung abscess, lung gangrene and empyema, which all tend to take a slow and indolent course. Preferred localization are dependent lung segments, most often on the right side. For bacteriological examination in these infections, only transtracheal aspirate and aspirate from the lung or pleural space are considered adequate. In 26 cases of empyema treated in our hospital during the last 3 years, adequate specimens had been taken in 19. Fifteen had been adequately examined, and anaerobes were cultured in 6. Among 29 abscesses treated during the same period, adequate specimens had been taken in only 14, and 11 had been properly examined. Seven specimens grew anaerobes on culture. In prospective studies of transtracheal aspirate in 15 chronic bronchitics without emphysema, anaerobes were not demonstrated. In 11 patients with bronchiectasis, anaerobic bacteria were cultured in 3. Finally, no anaerobic bacteria could be demonstrated in the transtracheal aspirate from 76 patients with acute exacerbation of chronic bronchitis. Anaerobic, pulmonary infections do not represent an intriguing medical problem in our region. However, knowledge of these infections is necessary to secure adequacy in collection of specimens and in their bacteriological examination.