PURPOSE: To understand the importance of Pseudomonas aeruginosa quorum-sensing systems in the development of corneal infection, the genotypic characteristics and pathogenesis of seven ocular isolates with low-protease and acyl homoserine lactone (AHL) activity and quorum-sensing mutants of PAO1 deficient in lasI, lasR, or rhlR were investigated in the study. METHODS: The possession of the quorum-sensing genes lasI, lasR, rhlI, rhlR, and the quorum-sensing controlled genes lasB, aprA, and rhlAB in the clinical isolates were determined by polymerase chain reaction and Southern blot hybridization. Elastinolytic activity, controlled by the las system, was assayed using elastin Congo red and rhamnolipid production controlled by the rhl system was assessed using agar plates containing methylene blue/cetyltrimethyl ammonium bromide. Induction of keratitis was examined in a scarified inbred BALB/c mouse model. RESULTS: The clinical isolates Paer1 and -3 were lasI and lasR negative, and the isolates Paer2 and -4 were rhlR and rhlAB negative. The isolates Paer17, Paer26, 6294 and 6206 possessed all the genes examined. There was no rhamnolipid production in clinical isolates Paer2 and -4. The isolates Paer1 and -3 were virtually avirulent in the scarified mouse corneas. Using isogenic PAO1 mutants, strain lasI showed a markedly reduced virulence in the corneal infection model. The remainder of the clinical isolates and the lasR or rhlR mutant strains caused severe keratitis. CONCLUSIONS: These results indicate that quorum-sensing deficiency may occur naturally in clinical isolates, and the possession of lasI and hence a functional Las quorum-sensing system may be important in development of corneal infection.
PURPOSE: To understand the importance of Pseudomonas aeruginosa quorum-sensing systems in the development of corneal infection, the genotypic characteristics and pathogenesis of seven ocular isolates with low-protease and acyl homoserine lactone (AHL) activity and quorum-sensing mutants of PAO1 deficient in lasI, lasR, or rhlR were investigated in the study. METHODS: The possession of the quorum-sensing genes lasI, lasR, rhlI, rhlR, and the quorum-sensing controlled genes lasB, aprA, and rhlAB in the clinical isolates were determined by polymerase chain reaction and Southern blot hybridization. Elastinolytic activity, controlled by the las system, was assayed using elastin Congo red and rhamnolipid production controlled by the rhl system was assessed using agar plates containing methylene blue/cetyltrimethyl ammonium bromide. Induction of keratitis was examined in a scarified inbred BALB/c mouse model. RESULTS: The clinical isolates Paer1 and -3 were lasI and lasR negative, and the isolates Paer2 and -4 were rhlR and rhlAB negative. The isolates Paer17, Paer26, 6294 and 6206 possessed all the genes examined. There was no rhamnolipid production in clinical isolates Paer2 and -4. The isolates Paer1 and -3 were virtually avirulent in the scarified mouse corneas. Using isogenic PAO1 mutants, strain lasI showed a markedly reduced virulence in the corneal infection model. The remainder of the clinical isolates and the lasR or rhlR mutant strains caused severe keratitis. CONCLUSIONS: These results indicate that quorum-sensing deficiency may occur naturally in clinical isolates, and the possession of lasI and hence a functional Las quorum-sensing system may be important in development of corneal infection.
Authors: David A D'Argenio; Manhong Wu; Lucas R Hoffman; Hemantha D Kulasekara; Eric Déziel; Eric E Smith; Hai Nguyen; Robert K Ernst; Theodore J Larson Freeman; David H Spencer; Mitchell Brittnacher; Hillary S Hayden; Sara Selgrade; Mikkel Klausen; David R Goodlett; Jane L Burns; Bonnie W Ramsey; Samuel I Miller Journal: Mol Microbiol Date: 2007-04 Impact factor: 3.501
Authors: David A Stoltz; Egon A Ozer; Peter J Taft; Marilyn Barry; Lei Liu; Peter J Kiss; Thomas O Moninger; Matthew R Parsek; Joseph Zabner Journal: J Clin Invest Date: 2008-09 Impact factor: 14.808
Authors: Pholawat Tingpej; Lucas Smith; Barbara Rose; Hua Zhu; Tim Conibear; Khaled Al Nassafi; Jim Manos; Mark Elkins; Peter Bye; Mark Willcox; Scott Bell; Claire Wainwright; Colin Harbour Journal: J Clin Microbiol Date: 2007-03-28 Impact factor: 5.948
Authors: Lucas R Hoffman; Anthony R Richardson; Laura S Houston; Hemantha D Kulasekara; Willm Martens-Habbena; Mikkel Klausen; Jane L Burns; David A Stahl; Daniel J Hassett; Ferric C Fang; Samuel I Miller Journal: PLoS Pathog Date: 2010-01-08 Impact factor: 6.823