Project description:The present study examines changes in global gene expression patterns and in virulence factor-associated genes in an extended spectrum beta-lactamase (ESBL)-producing UPEC (ESBL019) during the morphologic transitions induced by an ineffective antibiotic and in the presence of human primary bladder epithelial cells. The morphological shifts induced by ineffective antibiotics are associated with significant transcriptional virulence alterations in ESBL-producing UPEC, which may affect survival and persistence in the urinary tract.
Project description:While ESBL and AmpC beta-lactamases barely degrade carbapenems, they are able to bind them and prevent them from interacting with penicillin binding proteins thereby preventing their effect. When these beta-lactamases are expressed at a high level and combined with a decreased influx of carbapenems due to a decrease in membrane permeability, Enterobacterales can become resistant to carbapenems. In this study we developed a LC-MS/MS assay for the detection of the E. coli porins OmpC and OmpF, it’s chromosomal AmpC beta-lactamase and the plasmid-mediated CMY-2 beta-lactamase. Subsequently, we cultured CMY-2 positive E. coli isolates in the presence of meropenem and analyzed mutants that showed increased resistance to meropenem using our developed assay and western blot. In all five selected strains, a decrease in OmpC and/or OmpF was the first event towards an increase in meropenem minimum inhibitory concentrations (MICs). Subsequently, in four of the five isolate series, MICs increased further after an increase in CMY-2-like production.
Project description:The study investigated the impact of acquired AmpC β-lactamases on global gene expression and cellular physiology in Enterobacterales. Isogenic Escherichia coli MG1655 strains carrying empty vector (p0) or plasmids encoding CMY-2, CMY-42, or CMY-145 β-lactamase variants were grown to mid-log phase in minimal M9 medium with kanamycin. Total RNA was extracted in three biological replicates, ribosomal RNA was depleted, and strand-specific libraries were sequenced. Reads were mapped to the E. coli K-12 reference genome and differential expression analysis was performed. Comparative transcriptomics revealed large gene expression changes associated with AmpC variant production, including consistent deregulation of genes involved in flagellar biosynthesis, motility, and additional metabolic functions. These RNA-seq data provide a transcriptomic framework to understand how distinct AmpC variants differentially reshape bacterial regulatory networks beyond β-lactam resistance.
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 global surge in multi-drug resistant bacteria, including extended-spectrum β-lactamase (ESBL)-producing Escherichia coli has led to a growing need for new antibacterial compounds. Despite being promising, the potential of fish-derived antimicrobial peptides (AMPs) in combating ESBL-E. coli is largely unexplored. In this study, native peptides were extracted from the skin mucus of farmed African Catfish, Clarias gariepinus, using a combination of 10 % acetic acid solvent hydrolysis, 5 kDa ultrafiltration, and C18 hydrophobic interactions. Peptides were then sequenced using Orbitrap Fusion Lumos Tribrid Mass Spectrometry. The identified peptides were screened for potential antibacterial activity using Random Forest and AdaBoost machine learning algorithms. The most promising peptide was then chemically synthesized and evaluated in vitro for safety on Rabbit red blood cells and activity against ESBL-E. coli (ATCC 35218) utilizing the spot-on-lawn and broth dilution methods. Eight short peptides were identified with 13 - 22 amino acid residues and molecular weight range of 968.42 to 2434.11 Da. Peptide, FACAP-II was non-hemolytic to rabbit erythrocytes (p>0.05), with Zone of Inhibition (ZOI) of 22.7 mm and Minimum Inhibitory concentration (MIC) of 91.3 μg/mL. The peptide is thus a candidate antibacterial compound with enormous potential applications in the pharmaceutical industry. However, further studies are still required to establish the upscale production strategy and optimize its activity and safety in vivo.
