Affiliation:
1. Department of Microbiology and Immunology1 and
2. Department of Surgery,2 Texas Tech University Health Sciences Center, Lubbock, Texas 79430, and
3. Department of Microbiology and Immunology, University of Rochester, Rochester, New York 146423
Abstract
ABSTRACT
The
Pseudomonas aeruginosa
quorum-sensing systems,
las
and
rhl
, control the production of numerous virulence factors. In this study, we have used the burned-mouse model to examine the contribution of quorum-sensing systems to the pathogenesis of
P. aeruginosa
infections in burn wounds. Different quorum-sensing mutants of
P. aeruginosa
PAO1 that were defective in the
lasR
,
lasI
, or
rhlI
gene or both the
lasI
and
rhlI
genes were utilized. The following parameters of the
P. aeruginosa
infection were examined: (i) lethality to the burned mouse, (ii) dissemination of the
P. aeruginosa
strain within the body of the infected mouse (by determining the numbers of CFU of
P. aeruginosa
within the liver and spleen), and (iii) spread of the
P. aeruginosa
strain within the burned skin (by determining the numbers of CFU of
P. aeruginosa
at the inoculation site and at a site about 15 mm from the inoculation site [distant site]). In comparison with that of PAO1, the in vivo virulence of
lasI
,
lasR
, and
rhlI
mutants was significantly reduced. However, the most significant reduction in in vivo virulence was seen with the
lasI rhlI
mutant. The numbers of CFU that were recovered from the livers, spleens, and skin of mice infected with different mutants were significantly lower than those of PAO1. At 8 and 16 h post burn infection, comparable numbers of CFU of PAO1 and
lasI
and
rhlI
mutants were obtained from both the inoculation and distant sites of the burned skin of infected mice. In contrast, CFU of the
lasR
mutant and the
lasI rhlI
double mutant were recovered only from the inoculation site of infected mice at 8 and 16 h post burn infection. The ability of a plasmid carrying either the
lasI
or
rhlI
gene or the
lasI
and
rhlI
genes to complement the defect of the
lasI rhlI
double mutant was also examined. The presence of any of these plasmids within the
lasI rhlI
double mutant significantly enhanced its in vivo virulence, as well as its ability to spread within the burned skin. These results suggest that the quorum-sensing systems play an important role in the horizontal spread of
P. aeruginosa
within burned skin and in the dissemination of
P. aeruginosa
within the bodies of burned-and-infected mice and contributed to the overall virulence of
P. aeruginosa
in this animal model.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
355 articles.
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