Role of Pseudomonas aeruginosa quorum-sensing systems in a mouse model of chronic respiratory infection.

The role of quorum-sensing systems in a mouse model of chronic Pseudomonas aeruginosa infection was studied. A chronic P. aeruginosa respiratory infection model was established by placement of a tube pre-coated with strain PAO1 (wild-type) or a quorum-sensing mutant, namely PAO-JP1 (Delta lasI), PDO100 (Delta rhlI) or PAO-JP2 (Delta lasI/Delta rhlI), in the bronchus. At day 14 after infection, the numbers of viable bacteria in the quorum-sensing-mutant groups were lower than in the wild-type group. Histopathological examination showed milder inflammatory changes in the lungs infected with the mutant groups compared with the wild-type group. In the bronchoalveolar lavage fluid from the quorum-sensing-system-mutant groups the proportion of neutrophils was lower than in wild-type group. These findings indicate that the quorum-sensing system plays an important role in chronic P. aeruginosa respiratory infection.