Maintained susceptibility to fosfomycin in extra-hospitalary urinary isolates of Escherichia coli. Strong association of fosfomycin resistance with age and ESBL production

Introduction. Escherichia coli is isolated in most of uncomplicated community-acquired urinary tract infections (UTI) and fosfomycin is one of the treatments of choice. We analyzed the evolution of fosfomycin resistance in extrahospitalary E. coli urinary isolates and whether age and extended spectrum beta-lactamase (ESBL) production were associated to antibiotic resistance. Methods. A retrospective descriptive study was conducted from January 2017 to December 2022 including E. coli isolates from extrahospitalary urine samples. Results. The susceptibility to fosfomycin remained above 95% during the study period. ESBL production and age above 80 years were significantly associated with increased fosfomycin resistance. We also analyzed the consumption of fosfomycin and it remained stable, although it was higher in the population >65 years. Conclusions. Greater resistance is observed in ESBL-producing strains and in patients over 65 years of age. A stable consumption of fosfomycin is associated with low resistance percentages maintained over the time.