A Clinical Study of Chronic Lower Respiratory Tract Infections with Pseudomonas aeruginosa by Transtracheal Aspiration

We investigated the yearly changes of the incidence of Pseudomonas aeruginosa (P. aeruginosa) isolated from chronic lower respiratory tract infections (CLRTI), and also performed a clinical study on CLRTI with P. aeruginosa by transtracheal aspiration (TTA) to clarify the recent trend of P. aeruginosa infection in CLRTI and the predisposing clinical factors to the acute exacerbation. The isolation rate of P. aeruginosa among the total isolated bacteria in CLRTI between December 1978 and March 1983 was 8.4%, but it increased to 23.1% between April 1988 and March 1993. In 69 episodes (40 cases) of P. aeruginosa isolated from CLRTI between April 1983 and March 1993, monomicrobial infections of P. aeruginosa were 42 episodes (60.9%) and polymicrobial infections were 27 episodes (39.1%). When the diseases were classified into acute exacerbated and non-exacerbated phases, polymicrobial infections were seen more in the former phase, and the principal organisms detected with P. aeruginosa were Haemophilus influenzae and Streptococcus pneumoniae. In the acute exacerbated cases, predisposing conditions concerning the exacerbation were divided into four patterns: 1. polymicrobial infections with H. influenzae or S. pneumoniae, 2. after acute upper respiratory tract infections due to viral superinfection, 3. early phase from bacterial replacement by P. aeruginosa, 4. immunocompromised states such as adrenal corticosteroid administration or systemic underlying diseases. These results suggest that the importance of P. aeruginosa in CLRTI is increasing year by year and we must pay attention to the fact that P. aeruginosa alone may also cause acute exacerbation in the latter 2 patterns of the condition.