Project description:Chronic Pseudomonas aeruginosa infections evades antibiotic therapy and are associated with mortality in cystic fibrosis (CF) patients. We find that in vitro resistance evolution of P.aeruginosa towards clinically relevant antibiotics leads to phenotypic convergence towards distinct states. These states are associated with collateral sensitivity towards several antibiotic classes and encoded by mutations in antibiotic resistance genes, including transcriptional regulator nfxB. Longitudinal analysis of isolates from CF patients reveals similar and defined phenotypic states, which are associated with extinction of specific sub-lineages in patients. In depth investigation of chronic P.aeruginosa populations in a CF patient during antibiotic therapy revealed dramatic genotypic and phenotypic convergence. Notably, fluoroquinolone-resistant subpopulations harboring nfxB mutations were eradicated by antibiotic therapy as predicted by our in vitro data. This study supports the hypothesis that antibiotic treatment of chronic infections can be optimized by targeting phenotypic states associated with specific mutations to improve treatment success in chronic infections.
Project description:Pseudomonas aeruginosa chronically colonizes the lungs of individuals with CF, where it reaches high cell densities and produces a battery of virulence factors. Upon infection, a single strain of P. aeruginosa can colonize an individual’s lungs throughout his or her lifetime. To understand the evolution of P. aeruginosa during chronic lung infection, we conducted both genotypic and phenotypic analyses on clinical isogenic strains obtained from the lungs of three different individuals with CF. These strains were isolated over a period of approximately ten years and possess phenotypes that are commonly observed in isolates from the CF lung, such as the antibiotic resistant dwarf and mucoid phenotypes. Microarray analyses were carried out on isolates grown in a chemically defined medium that mimics the nutritional environment of the CF lung, synthetic CF sputum medium (SCFM).
2010-05-25 | GSE21966 | GEO
Project description:Pseudomonas aeruginosa Biofilm Developed in Chronic Wounds
Project description:Pseudomonas aeruginosa chronically colonizes the lungs of individuals with CF, where it reaches high cell densities and produces a battery of virulence factors. Upon infection, a single strain of P. aeruginosa can colonize an individualâs lungs throughout his or her lifetime. To understand the evolution of P. aeruginosa during chronic lung infection, we conducted both genotypic and phenotypic analyses on clinical isogenic strains obtained from the lungs of three different individuals with CF. These strains were isolated over a period of approximately ten years and possess phenotypes that are commonly observed in isolates from the CF lung, such as the antibiotic resistant dwarf and mucoid phenotypes. Microarray analyses were carried out on isolates grown in a chemically defined medium that mimics the nutritional environment of the CF lung, synthetic CF sputum medium (SCFM). 17 clinically isolated P. aeruginosa strains from three individuals with CF (5 strains from individual P1, 7 strains from individual P2, 5 strains from individual P3). Two reference strains PAO1 and PA14. All experiments were biologically duplicated.
Project description:Pseudomonas aeruginosa is a predominant pathogen in chronic lung infections in individuals with cystic fibrosis (CF). Epidemic strains of P. aeruginosa, such as the Liverpool Epidemic Strain (LES), are capable of transferring between CF patients and have been associated with increased hospital visits and antibiotic treatments. Comparative genomics and phenotypic assays have shown that antibiotic resistance profiles differ among LES isolates and that genotype–phenotype associations are difficult to establish for resistance phenotypes in clinical isolates of P. aeruginosa based on these comparisons alone. We compared two LES isolates, LESlike1 and LESB58, and the common laboratory strain P. aeruginosa PAO1 using label-free quantitative proteomics to more accurately predict functional differences between strains. The proteomes of the LES isolates were found to be more similar to each other than to PAO1. However, we also observed a number of differences in the abundance of proteins involved in quorum sensing, virulence, and antibiotic resistance, including in the comparison of LESlike1 and LESB58. Specifically, the proteomic data revealed a higher abundance of proteins involved in polymyxin and aminoglycoside resistance in LESlike1. Minimum inhibitory concentration assays confirmed that LESlike1 has higher resistance to antibiotics from these classes. These findings provide an example of the ability of proteomic data to complement genotypic and phenotypic studies to understand resistance in clinical isolates.
Project description:Pseudomonas aeruginosa (PA) is an opportunistic pathogen frequently isolated from cutaneous chronic wounds. How PA, in the presence of oxidative stress (OS), colonizes chronic wounds and forms a biofilm is still unknown. The purpose of this study is to investigate the changes in gene expression seen when PA is challenged with the high levels of OS present in chronic wounds. We used a biofilm-forming PA strain isolated from the chronic wounds of our murine model (RPA) and performed a qPCR to obtain gene expression patterns as RPA developed a biofilm in vitro in the presence of high levels of OS, and then compared the findings in vivo, in our mouse model of chronic wounds. We found that the planktonic bacteria under OS conditions overex-pressed quorum sensing genes that are important for the bacteria to communicate with each other, antioxidant stress genes important to reduce OS in the microenvironment for survival, biofilm formation genes and virulence genes. Additionally, we performed RNAseq in vivo and identified the activation of novel genes/pathways of the Type VI Secretion System (T6SS) involved in RPA pathogenicity. In conclusion, RPA appears to survive the high OS microenvironment in chronic wounds and colonizes these wounds by turning on virulence, biofilm-forming and survival genes. These findings reveal pathways that may be promising targets for new therapies aimed at dis-rupting PA-containing biofilms immediately after debridement to facilitate the treatment of chronic human wounds.
Project description:Characterization of the sRNA content of OMVs harvested from Pseudomonas aeruginosa strain PA14 LB cultue with and without tobramycin (1ug/mL)
Project description:Pseudomonas aeruginosa airway infection is the primary cause of death in Cystic Fibrosis (CF). During early infection P. aeruginosa produces multiple virulence factors, which cause acute pulmonary disease and are largely regulated by quorum sensing (QS) intercellular signalling networks. Longitudinal clinical studies have observed the loss, through adaptive mutation, of QS and QS-related virulence in late chronic infection. Although the mechanisms are not understood, infection with QS mutants has been linked to a worse outcome for CF patients. By comparing QS-active and QS-inactive P. aeruginosa CF isolates, we have identified novel virulence factors and pathways associated with QS disruption. In particular, we noted factors implicating increased intra-phagocyte survival. Our data present novel targets as candidates for future CF therapies. Some of these targets are already the subject of drug development programmes for the treatment of other bacterial pathogens and may provide cross-over benefit to the CF population. Refer to individual Series. This SuperSeries is composed of the following subset Series: GSE25128: Gene expression data from Pseudomonas aeruginosa strains isolated from cystic fibrosis lung infections GSE25129: Comparative genomic hybridisation data from Pseudomonas aeruginosa strains isolated from cystic fibrosis lung infections