Antibiotic Resistance Patterns Among Uropathogens in Female Outpatients Affected by Uncomplicated Cystitis: Focus on Fosfomycin Trometamol

Objectives: To report the resistance rate against fosfomycin trometamol among outpatient women with symptoms related to urinary tract infections over a 6-year period in a multicentre, cross-sectional study. Methods: Urinary samples were collected from three high-volume laboratories from January 2015 to December 2020. The pattern of resistance to fosfomycin was analysed by using the Vitek II automated system. Results: A total of 7289 urinary samples were collected and 8321 strains were analysed during the study period. The most commonly isolated uropathogen was Escherichia coli (n = 6583, 79.1%). The mean resistance rate against fosfomycin was 9.7% (range 7.1-11.3). No statistically significant difference was found between the three laboratories (P = 0.53). There was no significant increase in resistance rate during the study period. The mean resistance rate against fosfomycin was higher among extended-spectrum β-lactamase (ESBL)-producing bacteria when compared with non-ESBL-producing strains (10.8% vs. 7.9%; P < 0.001). Conclusion: Uropathogens isolated from women affected by cystitis remained highly susceptible to fosfomycin. These findings confirm recommendations in international guidelines that advocate fosfomycin trometamol for empirical treatment of uncomplicated cystitis in women.