Antimicrobial Resistance and Molecular Characterization of Gene Cassettes from Class 1 Integrons in Escherichia coli Strains

Genomic characterization of multi drug resistant ESBL-producing Escherichia coli isolates from patients and patient environments in a teaching hospital in Ghana

BACKGROUND

ESBL-producing Escherichia coli pose a growing health risk in community and healthcare settings. We investigated the resistome, virulome, mobilome, and genetic relatedness of multidrug-resistant (MDR) E. coli isolates from patients and their environment in a Ghanaian teaching hospital.

MATERIALS AND METHODS

Twenty-three MDR ESBL-producing or carbapenem-resistant E. coli isolates from a collection of MDR Gram-negative bacteria (GNB) from patients and environments were selected for genomic analyses. Whole genome sequencing and bioinformatics tools were used to analyze genomic characteristics and phylogeny.

RESULTS

The prevalence and incidence of rectal carriage of ESBL E. coli among patients were 13.65% and 11.32% respectively. The β-lactamase genes, blaTEM-1B (10 isolates) and blaCTX-M-15 (12 isolates) were commonly associated with IncFIB plasmid replicons and co-occurred with aminoglycoside, macrolide, and sulfamethoxazole/trimethoprim resistance. Insertion sequences, transposons, and class I integrons were found with blaCTX-M-15. Carriage and environmental isolates carried multiple virulence genes, with terC being the most prevalent in 21 isolates. Seventeen sequence types (STs) were identified, including a novel ST (ST13846). Phylogenetic analysis grouped the isolates into four main clusters, with one outlier. High genetic relatedness was observed between two carriage isolates of ST940 and between a carriage isolate and an environmental isolate of ST648. Isolates with different STs, collected at different times and locations, also showed genetic similarities.

CONCLUSION

We identified ESBL-producing E. coli with diverse genomic characteristics circulating in different hospital directorates. Clonal relatedness was observed among isolates from patients and the environment, as well as between different patients, suggesting transmission within and between sources.

Whole genome sequencing of uropathogenic E. coli from Ireland reveals diverse resistance mechanisms and strong correlation with phenotypic (EUCAST) susceptibility testing

Urinary tract infections (UTI) caused by uropathogenic Escherichia coli (UPEC) pose a global health concern. Resistance mechanisms, including genetic mutations in antimicrobial target genes, efflux pumps, and drug deactivating enzymes, hinder clinical treatment. These resistance factors often spread through mobile genetic elements. Molecular techniques like whole genome sequencing (WGS), multilocus sequence typing (MLST), and phylotyping help decode bacterial genomes and categorise resistance genes. In this study, we analysed 57 UPEC isolates from different UTI patients following EUCAST guidelines. A selection of 17 representative strains underwent WGS, phylotyping, MLST, and comparative analysis to connect laboratory susceptibility data with predictive genomics based on key resistance genes and chromosomal mutations in antimicrobial targets. Trimethoprim resistance consistently correlated with dfr genes, with six different alleles detected among the isolates. These dfr genes often coexisted with class 1 integrons, with the most common gene cassette combining dfr and aadA. Furthermore, 52.9% of isolates harboured the blaTem-1 gene, rendering resistance to ampicillin and amoxicillin. Ciprofloxacin-resistant strains exhibited mutations in GyrA, GyrB and ParC, plasmid-mediated quinolone resistance genes (qnrb10), and aac(6')-Ib-cr5. Nitrofurantoin resistance in one isolate stemmed from a four amino acid deletion in NfsB. These findings illustrate the varied strategies employed by UPEC to resist antibiotics and the correlation between clinical susceptibility testing and molecular determinants. As molecular testing gains prominence in clinical applications, understanding key resistance determinants becomes crucial for accurate susceptibility testing and guiding effective antimicrobial therapy.

Uropathogenic Escherichia coli (UPEC)-Associated Urinary Tract Infections: The Molecular Basis for Challenges to Effective Treatment

Urinary tract infections (UTIs) are among the most common bacterial infections, especially among women and older adults, leading to a significant global healthcare cost burden. Uropathogenic Escherichia coli (UPEC) are the most common cause and accounts for the majority of community-acquired UTIs. Infection by UPEC can cause discomfort, polyuria, and fever. More serious clinical consequences can result in urosepsis, kidney damage, and death. UPEC is a highly adaptive pathogen which presents significant treatment challenges rooted in a complex interplay of molecular factors that allow UPEC to evade host defences, persist within the urinary tract, and resist antibiotic therapy. This review discusses these factors, which include the key genes responsible for adhesion, toxin production, and iron acquisition. Additionally, it addresses antibiotic resistance mechanisms, including chromosomal gene mutations, antibiotic deactivating enzymes, drug efflux, and the role of mobile genetic elements in their dissemination. Furthermore, we provide a forward-looking analysis of emerging alternative therapies, such as phage therapy, nano-formulations, and interventions based on nanomaterials, as well as vaccines and strategies for immunomodulation. This review underscores the continued need for research into the molecular basis of pathogenesis and antimicrobial resistance in the treatment of UPEC, as well as the need for clinically guided treatment of UTIs, particularly in light of the rapid spread of multidrug resistance.

Occurrence of Serratia marcescens Carrying blaIMP-26 and mcr-9 in Southern China: New Insights in the Evolution of Megaplasmid IMP-26

The spread of multidrug-resistant enterobacteria strains has posed a significant concern in public health, especially when the strain harbors metallo-beta-lactamase (MBL)-encoding and mobilized colistin resistance (mcr) genes as such genetic components potentially mediate multidrug resistance. Here we report an IncHI2/2A plasmid carrying bla_IMP-26 and mcr-9 in multidrug-resistant Serratia marcescens human isolates YL4. Antimicrobial susceptibility testing was performed by the broth microdilution method. According to the results, S. marcescens YL4 was resistant to several antimicrobials, including β-lactams, fluorquinolones, sulfanilamide, glycylcycline, and aminoglycosides, except for amikacin. To investigate the plasmid further, we conducted whole-genome sequencing and sequence analysis. As shown, S. marcescens YL4 possessed a circular chromosome with 5,171,477 bp length and two plasmids, pYL4.1 (321,744 bp) and pYL4.2 (46,771 bp). Importantly, sharing high similarity with plasmids pZHZJ1 and pIMP-26, pYL4.1 has an IncHI2/2A backbone holding a variable region containing bla_IMP-26, mcr-9, and two copies of bla_TEM-1B. After comprehensively comparing relevant plasmids, we proposed an evolutionary pathway originating from ancestor pZHZJ1. Then, via an acquisition of the mcr-9 element and a few recombination events, this plasmid eventually evolved into pYL4.1 and pIMP-26 through two different pathways. In addition, the phage-like plasmid pYL4.2 also carried a bla_TEM-1B gene. Remarkably, this study first identified a multidrug-resistant S. marcescens strain co-harboring bla_IMP-26 and mcr-9 on a megaplasmid pYL4.1 and also included a proposed evolutionary pathway of epidemic megaplasmids carrying bla_IMP-26.