AlgR is a key Pseudomonas aeruginosa transcriptional response regulator required for virulence. AlgR activates alginate production and twitching motility but represses the Rhl quorum-sensing (QS) system, including rhamnolipid production. The role of AlgR phosphorylation is enigmatic, since phosphorylated AlgR (AlgR-P) is required for twitching motility through the fimU promoter but is not requi...

Whole-genome shotgun sequencing was used to study the sequence variation of three Pseudomonas aeruginosa isolates, two from clonal infections of cystic fibrosis patients and one from an aquatic environment, relative to the genomic sequence of reference strain PAO1. The majority of the PAO1 genome is represented in these strains; however, at least three prominent islands of PAO1-specific sequenc...

The Pseudomonas aeruginosa PAO1 gene pvdQ encodes an acyl-homoserine lactone (AHL) acylase capable of degrading N-(3-oxododecanoyl)-L-homoserine lactone by cleaving the AHL amide. PvdQ has been proven to function as a quorum quencher in vitro in a number of phenotypic assays. To address the question of whether PvdQ also shows quorum-quenching properties in vivo, an infection model based on the ...

Exposure of Pseudomonas aeruginosa to aminoglycosides frequently selects for recalcitrant subpopulations exhibiting an unstable, "adaptive" resistance to these antibiotics. In this study, we investigated the implication in the phenomenon of MexXY-OprM, an active efflux system known to export aminoglycosides in P. aeruginosa. Immunoblotting experiments demonstrated that the transporter MexY, but...

Induction of the MexCD-OprJ multidrug efflux pump was investigated in wild-type Pseudomonas aeruginosa PAO1. MexCD-OprJ was induced by clinically important disinfectants such as benzalkonium chloride and chlorhexidine gluconate, and by some cytotoxic agents such as tetraphenylphosphonium chloride, ethidium bromide and rhodamine 6G. MexCD-OprJ was not induced by norfloxacin, tetracycline, chlora...

The role of piliation in the development and course of acute pulmonary infection was examined using infant BALB/cByJ mice inoculated by intranasal instillation of isogenic Pil+ and Pil- mutants of Pseudomonas aeruginosa PA1244, PAK, and PAO1. The piliated strains caused more cases of pneumonia, bacteremia, and mortality than the nonpiliated strains (chi-square analysis, alpha = 0.001). The pili...

BACKGROUND Quorum sensing (QS) plays an important role in the production of virulence factors and pathogenicity in Pseudomonas aeruginosa, and the interruption of QS will be a hopeful pathway to combat bacterial infection. OBJECTIVE In this study, we selected Forsythia suspense (Thunb.) Vahl from traditional Chinese herbal medicines for its anti-QS activity. MATERIALS AND METHODS Anti-QS of...

Although Pseudomonas aeruginosa is an opportunistic pathogen that does not often naturally infect alternate hosts, such as plants, the plant-P. aeruginosa model has become a widely recognized system for identifying new virulence determinants and studying the pathogenesis of the organism. Here, we examine how both host factors and P. aeruginosa PAO1 gene expression are affected in planta after i...