Antimicrobial Susceptibility Patterns of Escherichia coli among Tunisian Outpatients with Community-Acquired Urinary Tract Infection (2012-2018)

Abstract

Introduction: Community-acquired urinary tract infection is one of the most common reasons for consultation in everyday practice; it represents a major source of antibiotic consumption. Escherichia coli (E. coli) is the main pathogen incriminated. Objective:· The aim of this study was to evaluate antimicrobial susceptibility patterns of community-acquired uropathogenic E coli throughout a 7-year period. Methodology: All strains of E. coli isolated from urine samples between January 1st 2012 and December 31st 2018 were included. Presence of ≥ 10³ CFU/ml in urine culture media was considered as significant for urinary tract infection. The identification of E. coli strains was realized using standard laboratory techniques. Antibiotic susceptibility testing was performed using the disk diffusion method according to the CA-SFM/ EUCAST criteria. Results: A total of 1,335 E. coli strains were isolated. Overall susceptibility rates to antimicrobial agents were as follows: ampicillin 39.1%, amoxicillin-clavulanic acid 64.9%, cefotaxime 94.9%, trimethoprim/sulfamethox-azole 67.6%, ciprofloxacin 89.2%, ofloxacin 86.9%, amikacin 98.6%, gentamicin 93.9%, nitrofurantoin 97.6% and fosfomycin 99.3%. All isolates were susceptible to carbapenems. The frequency of extended spectrum beta-lactamases-producing E. coli strains was 4.7%. Susceptibility rates of E. coli for ampicillin, trimethoprim/sulfamethoxazole and amikacin remained relatively stable over the study period, whereas susceptibility to amoxicillin-clavulanic acid, cefotaxime and fluoroquinolones showed a 2-phase pattern. As for gentamicin, a continuous decrease in susceptibility rates was observed. Conclusion: Antimicrobial susceptibility profiles of uropathogenic E. coli are constantly changing, due to modifications in the antibiogram interpretation criteria and antibiotic prescription habits. Rigorous surveillance of resistance rate is necessary to determine appropriate empirical treatment and limit the spread of multiresistant strains.