Evaluation of sensitivity profiles to fosfomycin in bacterial urine samples from outpatients.

Objective: To evaluate and compare the susceptibilities of bacteria found in outpatient cultures to fosfomycin and other main antibiotics commonly available in clinical practice.

Study Design: A retrospective cross-sectional study was conducted using 2,673 positive urine cultures collected between 2014 and 2017 at private laboratories located in the cities of Niterói and São Gonçalo. Susceptibilities to fosfomycin and other antibiotics were tested using the McNemar test with the level of significance set at 5 %.

Results: Out of the 2,673 samples tested, 94.1 % were susceptible to fosfomycin. Escherichia coli was responsible for 68.8 % of the positive samples, and susceptibility to fosfomycin was observed in 97.9 % of these cases. Susceptibility to fosfomycin in Klebsiella spp. represented 86.6 % of cases, Enterococcus spp., 94.9 % and Proteus mirabilis, 83.3 %. The highest rate of susceptibility for E. coli was observed with fosfomycin, with the only exception being imipenem (p < 0.001). Klebsiella spp. showed a similar profile, except that there was no difference between susceptibilities to fosfomycin and gentamicin (p = 0.91). Susceptibility of Enterococcus spp. to fosfomycin was like that of nitrofurantoin and ampicillin. Finally, the susceptibility of P. mirabilis to fosfomycin was greater than it was for trimethoprim-sulfamethoxazole and nitrofurantoin.

Conclusions: The microbiological profile established here shows substantial sensitivity to fosfomycin in the urine samples analysed. In most cases, there was a sensitivity profile that was favourable to the use of fosfomycin or at least comparable to the other antibiotics studied.