title: Role of the quorum-sensing system in experimental pneumonia due to Pseudomonas aeruginosa in rats.
abstract: The virulence of Pseudomonas aeruginosa is partly controlled by the las quorum-sensing system. A rat model of acute pneumonia was used to investigate the pathophysiological impact of this system by comparing the virulence of the wild-type virulent laboratory strain PAO1 with that of its lasR-deleted mutant PAOR. In comparison with PAO1, PAOR was avirulent after an instillation of 106 cfu (mortality rates, 72 versus 0%, respectively; p < 0.0001). A ten-fold higher inoculum slightly increased the mortality rate induced by PAOR (25%), which remained lower than that induced by PAO1 (75%, p = 0.0001). In addition, with both inocula lung and bronchoalveolar lavage bacterial counts were significantly lower in rats infected with PAOR than with PAO1 (p </= 0.01). Histopathological analysis showed that PAO1 induced a drastic vascular congestion and neutrophil infiltration of the lungs, whereas lung injury in rats infected with PAOR was mild with predominantly macrophage infiltration. This study adds evidence that the quorum-sensing system has an important role in the pathophysiology of P. aeruginosa pulmonary infection.
authors.affiliation: Service d'Immunologie Clinique, Hôpital Henri Mondor, 51 avenue du Maréchal de Lattre, 94010 Créteil, France. phillipe.lesprit@hmn.ap-hop-paris.fr
authors.forename: Philippe
authors.initials: P
authors.lastname: Lesprit
authors.forename: Francois
authors.initials: F
authors.lastname: Faurisson
authors.forename: Olivier
authors.initials: O
authors.lastname: Join-Lambert
authors.forename: Francoise
authors.initials: F
authors.lastname: Roudot-Thoraval
authors.forename: Maryline
authors.initials: M
authors.lastname: Foglino
authors.forename: Christiane
authors.initials: C
authors.lastname: Vissuzaine
authors.forename: Claude
authors.initials: C
authors.lastname: Carbon
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D008168:Lung / Q000382:microbiology; D008297:Male; D009154:Mutation; D018410:Pneumonia, Bacterial / Q000235:genetics / Q000382:microbiology* / Q000503:physiopathology; D011552:Pseudomonas Infections / Q000235:genetics* / Q000503:physiopathology; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000472:pathogenicity; D051381:Rats; D017207:Rats, Sprague-Dawley; D014774:Virulence