Susceptibility of urinary Enterobacteriaceae to selected antimicrobials in an out-patient setting in Wallonia-Belgium: retrospective analysis over 5 years period (2018-2022).

Objective: Increasing antimicrobial resistance in urinary tract infection is a major healthcare concern. In this study, we evaluate the patterns of resistance exhibited by the most implicated microorganisms in urine infections. This approach is a prerequisite for an appropriate and successful empiric therapy in ambulatory patients.

Methods: A retrospective study was carried out from January 2018 to September 2022 in Synlab-Collard laboratory, Liège, Belgium; a total of 129,939 Enterobacteriaceae isolated from 120,616 positive urine sample were included.

Results: Sex ratio is 81.6% female and 18.4% male. E. coli is the most common urinary pathogen (70.4% of cases), followed by Klebsiella spp. (13.5%), Proteus spp. (8.5%), and Citrobacter spp. (2.5%). Ampicillin shows the highest resistance at 56%. Nitrofurantoin, the recommended antimicrobial treatment for cystitis in Belgium, expresses an overall resistance rate of 19% in females and 32% in males peaking at 43% in males over 80 years. Fosfomycin and ciprofloxacin display higher resistance rates in subjects over the age of 80 (18%, 24% in females, and 25%, 35% in males respectively). Trimethoprim shows 24% and 29% resistance rate in females and males over the age of 80 respectively.

Conclusion: Even if empiric treatment of suspected UTIs may be of benefit in some cases, it is important for healthcare providers to carefully consider its limitations and evaluate its potential failure rate based on the resistance profiles of urinary Enterobacteriaceae. Susceptibility tests should be performed, and treatments adjusted especially in elderly populations.