In vitro activity of furazidin and comparator agents against bacterial isolates from urinary tract infections.

PURPOSE: Furazidin is a nitrofuran derivative used in Eastern Europe (e.g., Latvia, Lithuania and Poland) and Russia for treating uncomplicated urinary tract infections (UTI), while nitrofurantoin, another nitrofuran, is a widely used for this indication. This study (23-ADA-01) evaluated the activity of furazidin, nitrofurantoin, and fosfomycin against bacterial isolates collected between 2020 and 2022 from female UTI patients in 19 European and the Mediterranean countries.

METHODS

A total of 3,111 isolates were tested for susceptibility to furazidin, nitrofurantoin and fosfomycin using broth microdilution or agar dilution at a monitoring laboratory (JMI Laboratories, North Liberty, Iowa, USA). Minimum inhibitory concentration (MIC) results for antimicrobial agents commonly used to treat UTI, that were previously evaluated as part of the SENTRY Antimicrobial Surveillance Program, were added to the study for evaluation of cross-resistance. Additionally, minimum bactericidal concentration (MBC) testing was performed for 212 isolates.

RESULTS

Furazidin demonstrated high in vitro activity, especially against Escherichia coli (n = 1,758; MIC50/90, 4/8 mg/L; 99.0% inhibited at ≤ 32 mg/L), Staphylococcus saprophyticus (n = 168; MIC50/90, 2/2 mg/L; highest MIC 2 mg/L) and Enterococcus faecalis (n = 156; MIC50/90, 1/2 mg/L; highest MIC 16 mg/L). It was also effective against other pathogens such as Klebsiella pneumoniae, Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae, Staphylococcus aureus, Streptococcus agalactiae and Entercococcus faecium. Furazidin was fourfold more potent than nitrofurantoin against Enterobacterales and four- to eightfold more active against Gram-positive organisms. The MBC: MIC ratio for furazidin was ≤ 8 for all isolates tested, with 85.8% showing this ratio ≤ 2. Furazidin's activity against E. coli was consistent across the European countries, with MIC50 and MIC mode values of 4 mg/L. Isolates with higher furazidin MIC values also exhibited higher nitrofurantoin MIC values. Furazidin retained good activity against E. coli isolates resistant to fosfomycin or trimethoprim-sulfamethoxazole.

CONCLUSION

Our study demonstrates that furazidin exhibits potent in vitro activity against a broad spectrum of organisms responsible for UTIs. These data support furazidin as an effective alternative for treatment of UTIs.