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 purpose of this study is to determine whether the presence of pathogenic Escherichia coli in colon is associated with psychiatric disorders.
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.
