Exploring the TEM β-Lactamase in E. coli From Urinary Tract Infection Patient: Insights From Molecular Docking and...

Urinary tract infections (UTIs) caused by Escherichia coli (E. coli) are becoming increasingly difficult to treat due to rising antibiotic resistance, primarily driven by the production of β-lactamase enzymes such as TEM β-lactamase. Variations in the TEM gene can lead to reduced antibiotic efficacy; however, the specific effects of the resulting TEM protein variants on drug binding and enzyme stability remain largely underexplored.

In this study, we analyzed a single E. coli strain isolated from a UTI patient to characterize the interactions between its TEM β-lactamase and various antibiotics through molecular docking and dynamics simulations, aiming to better understand factors influencing antibiotic resistance and guide future therapeutic strategies.

The TEM β-lactamase gene from clinical isolates in the laboratory collection was amplified, sequenced, and translated into a protein model based on PDB ID 1JWV. This model was then used to analyze interactions with various antibiotics through molecular docking and molecular dynamics simulations. The computational findings were subsequently correlated with published in vitro susceptibility data.

Molecular docking analysis revealed that first-generation cephalosporins, such as cefazolin and cephalothin, exhibited strong binding affinities to TEM-1 β-lactamase (ΔG ≈ -8 kcal/mol) yet were resistant in vitro testing, indicating susceptibility to enzymatic hydrolysis. In contrast, second to fourth-generation cephalosporins (eg, cefuroxime, cefotaxime, cefepime) maintained similar binding energies but demonstrated sensitivity, suggesting enhanced structural resistance to β-lactamase. Aminoglycosides and fluoroquinolones showed varying binding affinities but retained in vitro activity, likely due to their distinct mechanisms targeting ribosomes or DNA gyrase, unaffected by TEM-1. Carbapenems, with lower binding energies, remained effective, consistent with their known β-lactamase resistance. These findings highlight the complexity of resistance, where binding energy alone does not determine antibiotic efficacy.

Molecular docking and dynamics simulations revealed that later-generation cephalosporins, carbapenems and aminoglycosides exhibit stable binding and structural resilience against TEM-1 β-lactamase. Despite strong docking and stable interactions observed for first-generation cephalosporins, their clinical inefficacy is due to enzymatic hydrolysis. These findings emphasize that integrating computational binding and stability data with structural and clinical insights is crucial for predicting effective antibiotics against TEM-1-mediated resistance.