Project description:Colistin is a crucial last-line drug used for the treatment of life-threatening infections caused by multi-drug resistant strains of the Gram-negative bacteria, Acinetobacter baumannii. However, colistin resistant A. baumannii isolates can be isolated following failed colistin therapy. Resistance is most often mediated by the addition of phosphoethanolamine (pEtN) to lipid A by PmrC, following missense mutations in the pmrCAB operon encoding PmrC and the two-component signal transduction system PmrA/PmrB. We recovered an isogenic pair of A. baumannii isolates from a single patient before (6009-1) and after (6009-2) failed colistin treatment that displayed low/intermediate and high levels of colistin resistance, respectively. To understand how increased colistin-resistance arose, we genome sequenced each isolate which revealed that 6009-2 had an extra copy of the insertion sequence element ISAba125 within a gene encoding an H-NS-family transcriptional regulator. Consequently, transcriptomic analysis of the clinical isolates identified was performed and more than 150 genes as differentially expressed in the colistin-resistant, hns mutant, 6009-2. Importantly, the expression of eptA, encoding a second lipid A-specific pEtN transferase, but not pmrC, was significantly increased in the hns mutant. This is the first time an H-NS-family transcriptional regulator has been associated with a pEtN transferase and colistin resistance.
Project description:There is an urgent need for novel antibiotics against carbapenem and 3rd generation cephalosporin-resistant Gram-negative pathogens, for which the last-resort antibiotics have lost most of their efficacy. We describe here a novel class of synthetic antibiotics that was inspired from natural product-derived scaffolds. The antibiotics have an unprecedented mechanism of action, which targets the main component (BamA) of the Bam folding machinery required for folding and insertion of ß-barrel proteins into the outer membrane of Gram-negative bacteria. This OMPTA (outer membrane protein-targeting antibiotic) class shows potent activity against multidrug-resistant Gram-negative ESKAPE pathogens and overcomes colistin-resistance both in vitro and in vivo. A clinical candidate has the potential to address life threatening Gram-negative infections with high unmet medical need.
Project description:There is an urgent need for novel antibiotics against carbapenem and 3rd generation cephalosporin-resistant Gram-negative pathogens, for which the last-resort antibiotics have lost most of their efficacy. We describe here a novel class of synthetic antibiotics that was inspired from natural product-derived scaffolds. The antibiotics have an unprecedented mechanism of action, which targets the main component (BamA) of the Bam folding machinery required for folding and insertion of ß-barrel proteins into the outer membrane of Gram-negative bacteria. This OMPTA (outer membrane protein-targeting antibiotic) class shows potent activity against multidrug-resistant Gram-negative ESKAPE pathogens and overcomes colistin-resistance both in vitro and in vivo. A clinical candidate has the potential to address life threatening Gram-negative infections with high unmet medical need.
Project description:Colistin sulfate (polymixin E) is an antibiotic prescribed with resurging frequency for multidrug resistant gram negative bacterial infections. It is associated with nephrotoxicity in humans in up to 33% of cases. Little is known regarding genes involved in colistin nephrotoxicity. A murine model of colistin-mediated kidney injury was developed. C57/BL6 mice were administered saline or colistin at a dose of 16mg/kg/day in 2 divided doses. An Illumina gene expression array was performed on kidney RNA harvested 72 hours after first colistin dose to identify differentially expressed genes early in drug treatment. Array platform was MouseWG-6, 48,000 probes. Drug given intraperitoneal.
2013-11-05 | GSE46410 | GEO
Project description:Colistin-resistant Gram-negative bacteria isolated from the hospital water environment
Project description:Colistin sulfate (polymixin E) is an antibiotic prescribed with resurging frequency for multidrug resistant gram negative bacterial infections. It is associated with nephrotoxicity in humans in up to 33% of cases. Little is known regarding genes involved in colistin nephrotoxicity. A murine model of colistin-mediated kidney injury was developed. C57/BL6 mice were administered saline or colistin at a dose of 16mg/kg/day in 2 divided doses. An Illumina gene expression array was performed on kidney RNA harvested 72 hours after first colistin dose to identify differentially expressed genes early in drug treatment. Array platform was MouseWG-6, 48,000 probes. Drug given intraperitoneal. Total RNA was isolated from mouse kidneys which were harvested upon sacrifice. 12 total 10 week old C57 bl6 mice were analyzed. Six mice were administered 0.1% saline twice daily, six mice were given colistin at 16 mg/kg/day in 2 divided doses. The 2 groups were randomized to 2 different MouseWG-6_V2_0_R2_11278593 and groups were compared.
Project description:Polymyxins are increasingly used as the critical last-resort therapeutic options for multidrug-resistant gram-negative bacteria. Unfortunately, polymyxin resistance has increased gradually for the last few years. Although studies on mechanisms of polymyxin are expanding, system-wide analyses of the underlying mechanism for polymyxin resistance and stress response are still lacking. To understand how Klebsiella pneumoniae adapt to colistin (polymyxin E) pressure, we carried out proteomic analysis of Klebsiella pneumoniae strain cultured with different concentrations of colistin. Our results showed that the proteomic responses to colistin treatment in Klebsiella pneumoniae involving several pathways, including (i) gluconeogenesis and TCA cycle; (ii) arginine biosynthesis; (iii) porphyrin and chlorophyll metabolism; and (iv) enterobactin biosynthesis. Interestingly, decreased abundance of class A β-lactamases including TEM, SHV-11, SHV-4 were observed in cells treated with colistin. Moreover, we also present comprehensive proteome atlases of paired polymyxin-susceptible and -resistant Klebsiella pneumoniae strains. The polymyxin-resistant strain Ci, a mutant of Klebsiella pneumoniae ATCC BAA 2146, showed missense mutation in crrB. The crrB mutant Ci, which displayed lipid A modification with 4-amino-4-deoxy-L-arabinose (L-Ara4N) and palmitoylation, showed striking increases of CrrAB, PmrAB, PhoPQ, ArnBCADT and PagP. We hypothesize that crrB mutations induce elevated expression of the arnBCADTEF operon and pagP via PmrAB and PhoPQ. Moreover, multidrug efflux pump KexD, which was induced by crrB mutation, also contributed to colistin resistance. Overall, our results demonstrated proteomic responses to colistin treatment and the mechanism of CrrB-mediate colistin resistance, which may further offer valuable information to manage polymyxin resistance.