ObjectivesTo compare two therapeutic regimes in terms of bacterial eradication of post-menopausal with uncomplicated acute cystitis who complete antibiotic treatment. Materials and methodsA multicenter, randomized, prospective and controlled study between two short antibiotic regimes: fosfomycin trometamol (FMT) 3g, 2 doses separated by 72h and ciprofloxacin 250mg every 12h for 3 days. A total of 118 post-menopausal women were enrolled in the study. They underwent an initial urine culture to know the responsible microorganism and susceptibility to treatment. This was repeated 5–7 days and 4 weeks after the treatment to evaluate bacterial eradication. Clinical symptoms and treatment safety were also evaluated. ResultsThere were microbiological data at the onset of the treatment in 82 women (69.49%). Of these, 27 did not have positive culture at the first visit (30.51%), 76 (64.41%) fulfilled all the protocol requirements and adverse effects from the treatment were collected in 113 (95.76%) of the patients enrolled in the study. The germs isolated most frequently were Escherichia coli (E. coli) (76.83%), Klebsiella pneumoniae (K. pneumoniae) (7.32%), Proteus mirabilis (P. mirabilis) (4.89%) and Enterococo sp. (3.66%). In terms of efficacy, no differences were detected in the proportion of patients who achieved bacterial eradication between the two study arms: 62.16% of the patients who received FMT and 58.97% of those treated with ciprofloxacin (Chi-square, p=0.78). The proportion of patients who achieved clinical cure was also similar (86.49% for FMT and 82.05% for ciprofloxacin; square, p=0.59). These results indicate similar efficacy of both antibiotics in the treatment of uncomplicated lower tract urinary infection in post-menopausal women. In regards to safety data, the proportion of global adverse effects associated to the treatments was 3.45% for FMT and 9.09% for ciprofloxacin. Treatment compliance was 100% for FMT and 83.64% for ciprofloxacin. ConclusionsThe FMT administered at a dose of 3g every 72h (2 total doses) and ciprofloxacin at a dose of 250mg every 12h during 3 days (6 total doses) have a comparable efficacy profile in lower tract urinary infection in post-menopausal women who adequately comply with the treatment, also having comparable safety. The FMT has a better antimicrobial susceptibility profile and better rate of treatment compliance.