Haemphilus influenzae呼吸器感染症に関する臨床的および基礎的検討

Abstract

The present study was performed to analyze the clinical features of respira- tory tract infection due to Hemophilus influenzae (H. influenzae) based on the study of bacteriology using the method of transtracheal aspiration (TTA) and that of outer membrane protein (OMP) profiles by SDS-PAGE. This study included an attempt to isolate the active moiety of cytotoxity against bronchial epithelial cells from H. influenzae. The following results were obtained : (1) In acute respiratory tract infection due to H. influenzae, polymicrobial infection with Streptococcus pneumonae (S. Pneumonae) and Neisseria sp., as well as immunological status of patients were involved in contraction of pneumonia. In bronchitis cases, although many cases were monomicrobial infection, polymicrobial with α-streptococcus was found in some cases. (2) In patients with chronic lower respiratory tract infection (CLRTI) due to H. influen- zae, changes in OMP of this pathogen were closely associated with acute exacerbation of CLRTI. (3) In patients with CLRTI due to H. influenzae, the administration of clarithromycin (CAM) resulted in decrease in serum IL-6 levels during the early phase of treatment. This effect lasted as long as treatment of CAM was continued. (4) The protein with a molecular weight of 14 kDa, as determined by SDS-PAGE, was purified by ion-exchange chromatography, gel-filtration and chromatofocusing, and was found to exhibit cytotoxity against cultured normal human bronchial epithelial cells. These results suggest that respiratory infection caused by H. influenzae includes a variety of clinicopathological features, and that this pathogen may directly cause bronchial epith- elial damage by releasing a cytotoxic protein. Moreover, treatment of CAM may relieve CLRTI patients from sustained inflammation in the airway by supressing IL-6 production.