Bacterial Isolation and Antibiotic Resistance Patterns in Urinary Tract Infections: A Focus on Fosfomycin Resistance in E. coli

Abstract

Background: Urinary tract infections (UTIs) are one of the most common bacterial infections globally, with increasing antimicrobial resistance (AMR) posing a significant challenge to effective treatment. Objective: This study aims to isolate and identify bacterial uropathies, assess their antimicrobial susceptibility patterns, and determine the presence of Fosfomycin-resistant E. coli strains in a tertiary care hospital in Rajshahi, Bangladesh. Methods: A descriptive cross-sectional study was conducted at Rajshahi Medical College Hospital, Bangladesh, from January to December 2019. A total of 285 urine samples were collected from clinically suspected UTI patients. Bacterial identification was performed using culture, Gram staining, and biochemical tests. Antimicrobial susceptibility testing was conducted using the Kirby-Bauer disk diffusion method, following Clinical and Laboratory Standards Institute (CLSI) guidelines. Fosfomycin-resistant E. coli isolates were subjected to polymerase chain reaction (PCR) for the detection of the fosA3 gene. Data analysis was performed using SPSS version 24.0. Result: Among 285 participants, 53.68% (153/285) were culture positive, with E. coli (60.49%) being the most prevalent isolate. Gram-negative bacteria accounted for 83.95% of isolates. E. coli exhibited high resistance to Amoxiclav (79.59%) and Ciprofloxacin (56.12%), while showing highest sensitivity to Imipenem (88.78%). Fosfomycin resistance was detected in only 2 E. coli isolates. Other uropathogens such as Klebsiella spp., Pseudomonas spp., and Proteus spp. exhibited high resistance to cephalosporins but remained sensitive to carbapenems. Among Gram-positive bacteria, Staphylococcus aureus was fully susceptible to Levofloxacin, while Coagulase-negative Staphylococci (CoNS) showed 100% sensitivity to Linezolid. PCR analysis confirmed the presence of the fosA3 gene in the two Fosfomycin-resistant E. coli isolates. Conclusion: The study highlights E. coli as the dominant UTI pathogen with significant resistance to β-lactams and fluoroquinolones, reinforcing the importance of carbapenems and Fosfomycin as viable treatment options.