Pathogenic Bacteria of the Enterobacteriaceae Family: Mechanisms of Adaptation to the Host Organism, Modern Trends in Overcoming Antibiotic Resistance, Taking Into Account the Role of G-Quadruplexes in the Bacterial Genome

Gram-negative bacteria of the ESKAPE group belonging to the Enterobacteriaceae family are in the top of the WHO list of priority pathogens that pose the greatest threat to human health. This is due not only to the fact that these bacteria have developed resistance to a single antibiotic or a single class of antibiotics, but also to the emergence of multiple drug resistance, which leads to the higher morbidity and mortality rates, as well as an increased burden on the healthcare system. Enterobacteria from the ESKAPE group (Klebsiella pneumoniae, Enterobacter spp.) demonstrate high ecological plasticity, actively exchange with genes of virulence and antimicrobial resistance, and also participate in the development of chronic inflammatory and oncological diseases of the intestine. This review summarizes modern data on the key factors of enterobacterial pathogenicity and the causes of antibiotic resistance. As a comparison, data on well-studied pathogenic Escherichia coli lines, which also belong to the Enterobacteriaceae family, are presented. Special attention is paid to G-quadruplexes (G4s)—non-canonical secondary structures of nucleic acids that can form in regulatory regions of genes and modulate the virulence factors expression and genes responsible for stress adaptation. The data on the occurrence of G4 motifs in the genomes of enterobacteria are reviewed. The results on the effect of G4 binding with low molecular weight ligands on the vital activity of a bacterial cell, including the efflux systems suppression and the antibiotic sensitivity restoration, are discussed. Promising directions for further research have been identified, including the validation of G4 targets in clinical strains and the development of selective modulators for G4-mediated regulation.