SIGNIFICANCE OF PYOCINE TYPING IN CHRONIC PULMONARY DISEASE

Abstract

While pulmonary infection in cystic fibrosis (CF) is most often initially due to S.aureus, P.aeruginosa often emerges as the major pathogen. The latter may be typed by susceptibility to pyocines, antibacterial substances produced by certain P.aeruginosa and active only against certain other P.aeruginosa. To understand the role of this organism in the bacterial ecology of the respiratory tract, pyocine typing, utilizing NIH indicator strains, was performed on multiple P.aeruginosa isolates from 100 chronic pulmonary disease patients with and without CF, classified according to clinical condition. No specific types were characteristic of non-CF patients, but N-7, N-9, N-ll, N-13, and N-27 were most common to CF patients. Types N-7 and N-ll were found most frequently in those with severe impairment or exacerbation of pulmonary disease, while N-1 and/or N-4 was associated with improvement. Of CF patients in good clinical condition, 33% had N-1 and/or N-4, compared to only 15% of CF patients with severe impairment. Pyocines produced by N-1 and N-4 P.aeruginosa in vitro inhibit N-7 and N-11, but pyocines produced by N-7, N-9, N-11, N-13, and N-27 do not inhibit N-1 and N-4. It is concluded, therefore, that the presence of N-1 and/or N-4 P.aeruginosa may inhibit colonization by P.aeruginosa characteristic of more severe disease as can occur among staphylococci in other clinical conditions.