Nitrofurantoin: the return of an old friend in the wake of growing resistance

Abstract

Objective: To re-evaluate the first- and second-line therapies for treating uncomplicated urinary tract infection (UTI), as although fluoroquinolones are commonly used for this purpose, its level of use is thought to be inappropriately excessive and will eventually have a detrimental impact; thus we hypothesise that nitrofurantoin might be the best choice for this indication, due to its low frequency of use and its high susceptibility rate in common UTI pathogens.

Materials and methods: We retrospectively analysed antimicrobial susceptibility patterns of urinary isolates from 2003 to 2007, taken from a community-based institutional hospital in Brooklyn, NY, USA.

Results: In all, 10,417 cultures grew Escherichia coli from 2003 to 2007. Overall, from 2003 to 2007, 95.6% of E. coli urine isolates were susceptible to nitrofurantoin, with an average 2.3% resistance rate. By contrast, E. coli uropathogens had a mean 75.6% and 75.9% susceptibility and 24.2% and 24% resistance rate to both ciprofloxacin and levofloxacin, respectively. Co-trimoxazole (trimethoprim/sulfamethoxazole; 'TMP/SMX') had a mean 29% resistance rate to E. coli over the same 5-year period.

Conclusions: We consider that nitrofurantoin is a good fluoroquinolone-sparing alternative to co-trimoxazole; this study shows that nitrofurantoin is bactericidal to a mean of 95% of E. coli UTIs. Nitrofurantoin also has a resistance rate of 2.3%, by contrast to the quinolones (ciprofloxacin and levofloxacin), with resistant rates of approximately 24%, and Co-trimoxazole, with a resistant rate of 29%. Nitrofurantoin is an acceptable treatment for uncomplicated UTIs and should now be considered the first-line treatment. A reconsideration of UTI treatment guidelines might now be appropriate.