giovedì 12 luglio 2012

Mirtillo rosso e prevenzione delle infezioni urinarie

Uno studio condotto da un gruppo di ricercatori del National Taiwan University Hospital 
del National Taiwan University College of Medicine, arrivano così alla conclusione 
che assumere i mirtilli rossi sotto forma di succo o pastiglie aiuta a tenere lontano virus e batteri 
e a prevenire le infezioni del tratto urinario, 
"I risultati della presente meta-analisi supportano l'idea che il consumo di prodotti contenenti mirtillo 
possono proteggere contro le infezioni del tratto urinario in alcune popolazioni. 
Tuttavia, a causa della sostanziale eterogeneità tra gli studi, questa conclusione dovrebbe essere 
interpretata con grande cautela". 

Ecco l'articolo originale
Editor's Correspondence | 

Prophylaxis for Recurrent Urinary Tract Infections: Nitrofurantoin, Not Trimethoprim-Sulfamethoxazole or Cranberry Juice

Burke A. Cunha, MD
Arch Intern Med. 2012;172(1):82-83. doi:10.1001/archinternmed.2011.613
Text Size: A A A

I read with interest the article by Beerepoot et alon 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.Nitrofurantoin does not predispose to uropathogen resistance for prophylaxis and therapy of short or long duration.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.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.,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 (

Financial Disclosure: None reported.


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
PubMed CrossRef
Cunha BA. Effective antibiotic-resistance control strategies.  Lancet. 2001;357(9265):1307-1308
PubMed CrossRef
Cunha BA. Nitrofurantoin—current concepts.  Urology. 1988;32(1):67-71
PubMed CrossRef
McOsker CC, Fitzpatrick PM. Nitrofurantoin: mechanism of action and implications for resistance development in common uropathogens.  J Antimicrob Chemother. 1994;33(suppl A)  23-30
Cunha BA. The clinical significance of resistant uropathogens in ambulatory urinary tract infections in women.  Scand J Infect Dis. 2006;38(3):235-236
PubMed CrossRef

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