[Clinical study of anaerobic respiratory infection]

This clinical study involved 35 cases, anaerobic bacteria were detected by TTA (transtracheal aspiration) or percutaneous lung aspiration, or pleural puncture. These cases were treated over the last 8 years in our department. There were 9 empyema, 9 pneumonitis, 5 lung abscess, 1 necrotizing pneumonia and 11 chronic lower airway infection. In 13 cases (37%), anaerobic bacteria alone were detected, whereas both anaerobic and aerobic bacteria were observed in the other 22 cases (63%). Of all bacteria detected. Bacteroids and Peptostreptococcus were the most common. With respect to host factors involved in the pathogenesis of pleural and parenchymal infection, aspiration was though to be a major trigger in only 11 out of the 24 cases (46%). The other 13 cases (54%) showed no evidence of aspiration, indicating that some other triggers was responsible. In further study, these 13 cases were found either to be heavy smokers with Brinkman index of more than 600, or to show sign of chronic lower airway infection. Both conditions were characterized by an inhibition of the mucociliary transport in the lower airway. Therefore, this study suggested that in the case without apparent aspiration the failure of local defense mechanisms in the airway, as a result of heavy smoking and/or chronic lower airway infection are involved in the pathogenesis of anaerobic respiratory infection.