2023 58 B3

Assessing the Evolution of Antibiotic Resistance in E. coli Through Phylogenetic Analysis

By: Florentine van Nouhuijs, Erica Tate, Aleyna Isik, Fayeeza Shaik

Department: Biology

Faculty Advisor: Dr. Pleuni Pennings

Bacterial antibiotic resistance is a significant public health issue that is expected to persist in the future. Mutations in certain bacterial genes, including gyrA, gyrB, parC, and parE, can lead to antibiotic resistant bacterial infections. These genes encode proteins that are crucial for the function of DNA gyrase and topoisomerase IV enzymes, which play a key role in DNA replication, transcription, and recombination in bacteria. Antibiotics such as fluoroquinolones target these enzymes by binding to their active sites, inhibiting their function, and ultimately killing the bacterial cell. However, mutations in the mentioned genes can alter the structure of these enzymes, leading to reduced binding affinity between the enzymes and the antibiotic, resulting in reduced efficacy of the antibiotic and eventual antibiotic resistance. In this study we aimed to investigate the relationship between mutations in gyrA, gyrB, parC, and ParE genes and antibiotic resistance in Escherichia coli towards Ciprofloxacin. Using whole-genome sequencing data from E.coli isolates collected from patients with bacteremia in the UK, we employed phylogenetic trees and comparative methods to analyze the data and observed that the patterns of evolutionary change in resistance to Ciprofloxacin were consistent with sustained transmission of resistant strains from patient to patient. We also found that mutations in the mentioned genes were associated with the emergence and transmission of resistance, with cluster sizes generally larger in phylogroup B2, indicating that transmission of resistant strains is more common in this group. Our study highlights the potential of combining evolutionary genomics and epidemiology to investigate the evolution of antibiotic resistance in bacterial populations. These findings provide valuable insights into the mechanisms underlying the evolution and transmission of antibiotic resistance, which could inform the development of strategies to combat this growing public health concern.