Project description:Antimicrobials have been shown to select for changes in biofilm formation and multidrug susceptibility in common human pathogens. We investigated whether common food preservatives selected for these changes in the food pathogen Salmonella enterica serovar Typhimurium. Bacteria were exposed to four food preservatives in either planktonic cultures or biofilms grown on stainless steel beads. Cultures were passaged into fresh media supplemented with the food preservative every 72 hours. Following approximately 1000 generations of continuous preservative exposure, populations were sequenced to determine the single nucleotide polymorphisms that were selected for over evolutionary time.
Project description:Stenotrophomonas maltophilia is an emerging opportunistic multidrug-resistant pathogen frequently co-isolated with other relevant nosocomial pathogens in respiratory tract infections. S. maltophilia uses the endogenous DSF quorum sensing (QS) system to regulate virulence processes but can also respond to exogenous AHL signals produced by neighboring bacteria. A whole-transcriptome sequencing analysis was performed for S. maltophilia strain K279a in the exponential and stationary phases and in exponential cultures after a treatment with exogenous DSF or AHLs. Among the common top upregulated genes, the putative TetR-like regulator Smlt2053 was selected for functional characterization. This regulator was found to sense long-chain fatty acids, including the QS signal DSF, and activate a β-oxidation catabolic pathway.
Project description:Traditional vaccines are difficult to deploy against the diverse antibiotic-resistant, nosocomial pathogens that cause Hospital Acquired Infections (HAIs). We developed a unique, protein-free vaccine to present antibiotic-resistant HAIs. This vaccine protected mice from invasive infections caused by methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis, multidrug resistant Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, Rhizopus delemar, and Candida albicans. Protection persisted even in neutropenic mice infected with A. baumannii or R. delemar. Protection was already apparent after 24 hours and lasted for up to 21 days after a single dose, with a second dose restoring efficacy. Protection persisted without lymphocytes but was abrogated with macrophages depletion. This vaccine induced trained immunity by altering the macrophage epigenetic landscape and the inflammatory response to infection.
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:<p>Ceftazidime (CAZ) is a critically important broad-spectrum antibiotic widely used in clinical practice. However, the rapid emergence of bacterial resistance to CAZ poses a significant challenge in treating infections caused by multidrug-resistant pathogens. In this study, we employed a metabolism-reprogramming approach to characterize key features of laboratory-evolved CAZ-resistant Escherichia coli K12 and identified repressed glutamate metabolism as a reprogrammable target. Exogenous glutamate effectively resensitized both lab-evolved and clinically isolated multidrug-resistant E. coli strains to CAZ. The resensitization mechanism operates through two synergistic pathways driven by glutamate metabolic flux. First, glutamate conversion to inosine activates the inosine–CpxA–CpxR–OmpF regulatory axis, increasing outer membrane permeability. Second, glutamate entry into the pyruvate cycle restores the proton motive force (PMF), energizing the inner membrane. Together, increased outer membrane permeability and a restored PMF synergistically enhance intracellular accumulation of CAZ—by facilitating its entry through the widened OmpF porin and promoting its active uptake across the cytoplasmic membrane. This dual-mechanism strategy provides a novel two-pronged approach to overcoming CAZ resistance. Our findings underscore the potential of targeting bacterial metabolic pathways to restore susceptibility and extend the utility of existing antibiotics against resistant pathogens.</p><p>Keywords: Multidrug-resistant bacteria; E. coli; glutamate; CpxA/R-OmpF axis; proton motive force; metabolic state-reprogramming</p><p><br></p><p><br></p><p><br></p>
