Quorum-sensing activity and related virulence factor expression in clinically pathogenic isolates of Pseudomonas aeruginosa.
Respiratory isolates of Pseudomonas aeruginosa were collected from 58 critically-ill patients with ventilator-associated pneumonia. Expression of elastase and pyocyanin was assessed semi-quantitatively, while quorum-sensing activity was assessed by quantifying the levels of the autoinducers N-3-oxododecanoyl-L-homoserine lactone (C12-HSL) and N-butanoyl-L-homoserine lactone (C4-HSL). Correlations were sought between quorum-sensing activity and the expression of these two virulence factors, and all results were compared to those obtained with the laboratory reference strains PA103, a strain defective in quorum-sensing, and PAO1, a functional quorum-sensing strain. More than two-thirds of clinically pathogenic isolates had increased levels of elastase and/or pyocyanin, and high quorum-sensing activity, as assessed by autoinducer levels. However, a strong correlation between quorum-sensing activity and virulence factor production was revealed only for elastase and not for pyocyanin (C12-HSL/elastase, r = 0.7, p 2 x 10(-9); C4-HSL/elastase, r = 0.7, p 2 x 10(-9)). These data suggest that the pathogenicity of P. aeruginosa isolates from critically-ill patients with ventilator-associated pneumonia is caused, at least in part, by an increase in elastase production regulated by quorum-sensing, while increased pyocyanin production in these isolates may be regulated predominantly by mechanisms other than quorum-sensing.
Le Berre
R
R
Laboratoire de Recherche en Pathologie Infectieuse, Faculté de Médecine de Lille, Lille, France.
Nguyen
S
S
Nowak
E
E
Kipnis
E
E
Pierre
M
M
Ader
F
F
Courcol
R
R
Guery
B P
BP
Faure
K
K
D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000378:metabolism; D001426:Bacterial Proteins; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D010196:Pancreatic Elastase / Q000235:genetics / Q000378:metabolism; D053717:Pneumonia, Ventilator-Associated / Q000382:microbiology*; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000302:isolation & purification / Q000472:pathogenicity*; D011710:Pyocyanine / Q000235:genetics / Q000378:metabolism; D053038:Quorum Sensing; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D037521:Virulence Factors; C088386:homoserine lactone; D011710:Pyocyanine; D010196:Pancreatic Elastase; D015107:4-Butyrolactone