Project description:CF patients suffer from chronic and recurrent respiratory tract infections which eventually lead to lung failure followed by death. Pseudomonas aeruginosa is one of the major pathogens for CF patients and is the principal cause of mortality and morbidity in CF patients. Once it gets adapted, P. aeruginosa can persist for several decades in the respiratory tracts of CF patients, overcoming host defense mechanisms as well as intensive antibiotic therapies. P. aeruginosa CF strains isolated from different infection stage were selected for RNA extraction and hybridization on Affymetrix microarrays. Two batch of P. aeruginosa CF isolates are chosen : 1) isolates from a group of patients since 1973-2008 as described in ref (PMID: 21518885); 2) isolates from a group of newly infected children as described in ref (PMID: 20406284).
Project description:Antibiotic resistance is one of the most pressing threats to human health, yet recent work highlights how loss of resistance may also drive pathogenesis in some bacteria. In two recent studies, we found that in vitro beta-lactam antibiotic and nutrient stresses faced during infection selected for the genetic inactivation of the Pseudomonas aeruginosa (Pa) antibiotic efflux pump mexEFoprN. Unexpectedly, efflux pump mutations increased Pa virulence during infection; however, neither the prevalence of efflux pump inactivating mutations in real human infections, nor the mechanisms driving increased virulence of efflux pump mutants were known. We hypothesized that human infection would select for efflux pump mutations that drive increased virulence in Pa clinical isolates. Using genome sequencing of hundreds of Pa clinical isolates, we show that mexEFoprN efflux pump inactivating mutations are enriched in Pa cystic fibrosis isolates relative to Pa intensive care unit clinical isolates. Combining RNA-seq, metabolomics, genetic approaches, and infection models we show that efflux pump mutants increase expression of two key Pa virulence factors, elastase and rhamnolipids, which increased Pa virulence and lung damage during both acute and chronic infections. We show that increased virulence factor production was driven by increased Pseudomonas quinolone signal levels, and this mechanism of increased virulence held true in both a representative ICU clinical isolate and the notorious CF Pa Liverpool epidemic strain. Together, our findings suggest that mutations inactivating antibiotic resistance mechanisms could increase patient mortality and morbidity.
2024-11-12 | MSV000096391 | MassIVE
Project description:Pseudomonas aeruginosa strains from Intensive Care Unit environments and patients.