Project description:Unknown are the mechanisms of tolerance and persistence associated to several compounds in A.baumannii clinical isolates. Using transcriptomical and microbiological studies, we found a link between bacterial tolerance mechanisms to clorhexidine as well as the development of persistence in presence of imipenem in an A.baumannii strain belonging to ST-2 clinical clone (carbapenem-resistant with OXA-24 ß-lactamase and AbkAB TA system by plasmid). Interestingly, in A.baumannii ATCC17978 strain (carbapenem-susceptible isolate which carries AbkAB TA system by plasmid) showed persistence in presence of imipenem.
Project description:The emergence of colistin resistance in carbapenem-resistant and extended-spectrum ß-lactamase (ESBL)-producing bacteria is a significant threat to human health, and new treatment strategies are urgently required. Here we investigated the ability of the safe-for-human use ionophore PBT2 to restore antibiotic sensitivity in several polymyxin-resistant, ESBL-producing, carbapenem resistant Gram-negative human pathogens. PBT2 was observed to resensitize Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa to last-resort polymyxin class antibiotics, including a ‘next generation’ polymyxin derivative, FADDI-287. To gain additional insight into the potential mechanism of action of PBT2, we analyzed the transcriptome of K. pneumoniae and E. coli in the presence of sub-inhibitory concentrations of PBT2. Treatment with PBT2 was associated with multiple stress responses in both K. pneumoniae and E. coli. Significant changes in the transcription of transition metal ion homeostasis genes were observed in both strains.
Project description:The emergence of polymyxin resistance in carbapenem-resistant and extended-spectrum -lactamase (ESBL)-producing bacteria is a critical threat to human health, and new treatment strategies are urgently required. Here, we investigated the ability of the safe-for-human use ionophore PBT2 to restore antibiotic sensitivity in polymyxin-resistant, ESBL-producing, carbapenem-resistant Gram-negative human pathogens. PBT2 was observed to resensitize Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii and Pseudomonas aeruginosa to last-resort polymyxin class antibiotics, including the less-toxic next-generation polymyxin derivative, FADDI-287. We were unable to select for mutants resistant to PBT2 + FADDI-287 in polymyxin resistant E. coli containing a plasmid-borne mcr-1 gene or K. pneumoniae carrying a chromosomal mgrB mutation. Using a highly invasive K. pneumoniae strain engineered for polymyxin resistance through mgrB mutation, we successfully demonstrated the efficacy of PBT2 + FADDI-287 in vivo for the treatment of Gram-negative sepsis. These data present a new treatment modality to break antibiotic resistance in high priority polymyxin-resistant Gram-negative pathogens.
Project description:Pseudomonas aeruginosa (P. aeruginosa) lung infection is a significant cause of mortality in patients with cystic fibrosis (CF). Existing experimental data in our lab showed significantly different levels of virulence of "early" and "late" P. aeruginosa infection isolates in a C. elegans slow killing model. We wished to examine the expression profile of these isolates in order to explore genes that may be responsible for the observed differences. The expression profiles of two pairs of isolates (four isolates in total) were compared to each other using the Affymetrix P. aeruginosa PAO1 genome array, to gain insight into properties mediating virulence in these isolates. Data analysis was carried out using BIOCONDUCTOR software. Keywords: Comparative strain hybridization
Project description:The aim of this experiment was to determine if the development of resistance to antibiotics can be driven by the concentration and speciation of Cu. Experimental setup was designed to investigate two hypotheses for which two strains of Gram- bacteria have been selected: - Do TE enhance AR in resistant bacteria? Resistant strain: Bioluminescent Pseudomonas aeruginosa PAO1 (Xen41, Tetracycline resistant) - Do TE induce AR in sensitive bacteria? Sensitive strain: Pseudomonas aeruginosa PAO1 (Wild Type)
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).
Project description:The gene encoding elongation factor G, fusA1, is frequently mutated in clinical isolates of Pseudomonas aeruginosa from patients with cystic fibrosis. Recent work has shown that fusA1 mutants often display elevated aminoglycoside resistance due to increased expression of the aminoglycoside efflux pump, MexXY. We isolated a spontaneous gentamicin-resistant fusA1 mutant (FusA1-P443L) in which mexXY expression was increased. We compared the transcriptome of this fusA1 mutant (EMC1) with the P. aeruginosa PAO1-derived progenitor strain (EMC0) and complemented mutant strain expressing the wild-type fusA1 gene in trans (EMC1*).