# A Retrospective Analysis of Urinary Tract Infections With Special Reference to the Phenotypic and Genotypic Detection of Fosfomycin-Resistant Escherichia coli Isolates at a Tertiary Care Center in South India

## TL;DR

This study examines fosfomycin-resistant Escherichia coli in urinary tract infections at a South Indian hospital, finding limited resistance and a single isolate with the fosA3 gene.

## Contribution

The study identifies fosfomycin resistance in E. coli isolates and detects the fosA3 gene in one isolate, contributing to understanding antibiotic resistance patterns.

## Key findings

- 97% of Escherichia coli isolates were phenotypically susceptible to fosfomycin.
- Only one fosfomycin-resistant isolate tested positive for the fosA3 gene via RT-PCR.

## Abstract

One of the leading causes of morbidity worldwide is urinary tract infections (UTIs). We are already running out of antimicrobial drugs in this era of antimicrobial resistance. It is important to know the antimicrobial resistance pattern of all organisms that commonly cause human diseases.

The purpose of this investigation was to identify the pathogen that causes UTIs and to characterize the molecular makeup of the isolate of Escherichia coli that is resistant to fosfomycin in urine samples. A total of 1104 samples were examined during the June-August 2024 retrospective investigation at our institution. However, only 91 isolates of Escherichia coli were detected using standard microbiological methods. The Kirby-Bauer disk diffusion method was used to assess their susceptibility to antimicrobials. Of the 91 recovered Escherichia coli, 97% (n = 88) exhibited phenotypic susceptibility to fosfomycin, while the remaining 3 fosfomycin-resistant isolates underwent real-time polymerase chain reaction (RT-PCR). However, the fosA3 gene was detected in only one fosfomycin-resistant isolate.

While urinary tract infections are a common and widespread ailment that affects a large number of people worldwide, antibiotics are currently limited in their ability to treat them. Hence, fosfomycin may be the preferred choice of antibiotic.