Anaerobic Bacterial Infections of the Lung

Abstract

Anaerobic bacteria are relatively common pulmonary pathogens and they are especially frequent with aspiration pneumonia and its suppurative sequelae: lung abscess and empyema. The clinical features and bacteriology of this condition have been well described with extensive studies done in two periods. The first period was the turn of the century when anaerobic bacteria were initially discovered as important causes of empyema1 through the period of 1927–30 when David Smith at Duke completed classical studies of lung abscess.2–4 The second period of study extended from approximately 1968 through 1980 when there was extensive use of transtracheal aspiration as a mechanism to obtain uncontami-nated specimens from the lower respiratory tract; access to this culture source combined with a renewed interest in cultivating oxygen-sensitive bacteria permitted clinical and bacteriological features to be redefined to include therapeutic implications. Despite these advances, it should be acknowledged that the role of anaerobic bacteria as pulmonary pathogens is commonly overlooked. It is still rare to have the bacteriologic diagnosis established at the present time and there continues to be considerable controversy regarding antibiotic options. The present review is based on the author’s experience with 193 bacteriologically confirmed cases studied in the 1970s5,6 combined with some of the more recent work dealing with taxonomic changes, definition of virulence factors of anaerobic bacteria, and the potential role of newer antimicrobial agents.