Antibiotic resistance pattern of Escherichia coli causing urinary tract infection with an emphasis on fluoroquinolone resistance

INTRODUCTION: Urinary Tract Infections (UTIs) are one of the most common bacterial infections in humans, both in the community and the hospital settings. UTIs are more common in females compared to males and are mostly caused by Escherichia coli accounting for more than 70% of uncomplicated cases both in outpatients and inpatients. With increasing antibiotic resistance, management of urinary tract infection has become complicated with limited therapeutic options. OBJECTIVES: The present study was undertaken to detect the current antibiotic resistance pattern of Escherichia coli with a special reference to fluoroquinolone resistance. MATERIALS AND METHODS: A total of 1248 urine samples collected between November 2011 to May 2013 were cultured and pathogens identified by conventional methods. Antibiotic susceptibility pattern determined was by Kirby-Bauer method and the minimum inhibitory concentration (MIC) of fluoroquinolones was determined by microbroth dilution method as per CLSI guidelines. RESULTS: Among 311culture positive urine samples, 203 were Escherichia coli. High resistance rate to Ampicillin (81.3%), Co-trimoxazole (83.3%) and low resistance rate to Nitrofurantoin (17%) were noted for Escherichia coli. Among the 203 Escherichia coli, 141 and 121 isolates showed a MIC of ≥ 4 μg/ml for Ciprofloxacin and ≥ 8 μg/ml for Levofloxacin respectively. The resistance rate to other antibiotics and the MIC of Ciprofloxacin and Levofloxacin increased as the patient’s age increases. CONCLUSION: The increased resistance to fluoroquinolones in Escherichia coli could be due to its inappropriate usage. It is imperative to rationalize the use of fluoroquinolones in order to prevent the dissemination of resistant strains in the population