Epidemiological and Molecular Characteristics of Escherichia coli Isolates Causing Urinary Tract Infections in Central India

Background: Urinary tract infections (UTIs) remain one of the most common bacterial infections worldwide, with Escherichia coli being the predominant uropathogen. Increasing antimicrobial resistance and the emergence of extended-spectrum β-lactamase (ESBL)–producing strains pose serious therapeutic challenges.

Objective: This study aimed to investigate the epidemiological distribution, virulence attributes, antimicrobial resistance patterns, and molecular characteristics of E. coli isolates obtained from UTI patients in a tertiary care hospital in Central India.

Methods: A total of 2,483 urine samples were collected over 18 months from symptomatic and asymptomatic patients. Standard microbiological methods were used for isolation and identification. Virulence factors—including siderophore production, cell surface hydrophobicity, hemagglutination, hemolysin production, plasmid profiling, and ESBL production—were evaluated. Antimicrobial susceptibility testing was performed using the Kirby–Bauer disk diffusion method. Molecular detection of resistance genes was carried out using PCR and real-time PCR, followed by sequencing.

Results: E. coli was isolated from 230 (9.26%) samples, predominantly from symptomatic patients. Siderophore production (34.15%) and cell surface hydrophobicity (32.17%) were the most prevalent virulence factors among symptomatic isolates. ESBL production was detected in 9.56% of isolates. High resistance rates were observed for gentamicin (61.73%) and fluoroquinolones, while piperacillin–tazobactam showed the highest sensitivity (99.14%). Molecular analysis revealed the widespread presence of the CTX-M gene among multidrug-resistant isolates.

Conclusion: The study highlights the alarming burden of virulence-associated, multidrug-resistant E. coli in UTIs. Continuous surveillance, rational antibiotic use, and molecular monitoring of resistance genes are essential for effective UTI management.