I read with interest the article by Beerepoot et al1 on urinary tract infection (UTI) prophylaxis, which raises important points that merit comment. From a resistance perspective, the article re-emphasizes that trimethoprim-sulfamethoxazole (TMP-SMX) is a “high resistance potential” antibiotic that predisposes to resistance among uropathogens. Clinicians should be reminded that resistance is not related to antibiotic volume, duration, or class per se, but rather is associated with individual agents from all antibiotic classes.2 Nitrofurantoin does not predispose to uropathogen resistance for prophylaxis and therapy of short or long duration.3 Another point deserving re-emphasis is that antibiotics with a high resistance potential not only predispose to increased resistance during treatment but such resistant uropathogens may persist in fecal flora for up to 3 months following therapy. Clinicians should take great care in selecting an appropriate antibiotic with a low resistance potential, both to minimize the resistance potential and to prevent prolonged carriage of resistant uropathogens in the fecal flora.2
The study was intended to determine if cranberry juice had antibacterial effects. However, the most important take home message is to avoid TMP-SMX for prophylaxis or therapy of recurrent UTIs.1Instead, use nitrofurantoin, which is effective against most common uropathogens but does not predispose to resistance. Nitrofurantoin is effective against common uropathogens except Proteusspecies and Pseudomonas aeruginosa. Nitrofurantoin inhibits bacterial growth at 3 different loci in the Kreb's cycle of susceptible uropathogens.3 Nitrofurantoin, rather than TMP-SMX, is ideal for prophylaxis of recurrent lower UTIs and acute complicated cystitis in female patients.4
Another concern in the study is timing and duration of prophylaxis for recurrent UTIs. Excluding relapsing UTIs, reinfecting recurrent UTIs are best treated episodically with a “low resistance potential” antibiotic, eg, nitrofurantoin. It is preferable to treat a few episodes of cystitis per year as needed rather than to use prolonged prophylaxis with TMP-SMX with its associated costs and risks of adverse effects, eg, drug fever, Steven-Johnson syndrome, folate deficiency, cost of resistance, and prolonged carriage of uropathogens in the fecal flora.
In my clinical experience, nitrofurantoin has been useful for empirical initial prophylaxis and treatment of recurrent lower UTIs in women. The adverse effects of nitrofurantoin occur mainly with prolonged therapy with chronic renal insufficiency. Nitrofurantoin is a cost-effective and safe alternative to TMP-SMX and does not predispose to resistance.2 ,5 Clinicians should carefully consider the resistance potential of antibiotics selected for recurrent UTIs. Better alternatives than TMP-SMX, eg, nitrofurantoin, are available and have a long record of effectiveness and lack of resistance.
Correspondence: Dr Cunha, Chief, Infectious Disease Division, Winthrop-University Hospital, 222 Station Plaza N (Ste 432), Mineola, NY 11501 (firstname.lastname@example.org).
Beerepoot MA, ter Riet G, Nys S, et al. Cranberries vs antibiotics to prevent urinary tract infections: a randomized double-blind noninferiority trial in premenopausal women. Arch Intern Med. 2011;171(14):1270-1278 PubMedCrossRef