Reduction of Escherichia coli adherence to uroepithelial bladder cells after consumption of cranberry juice: a double-blind randomized placebo-controlled cross-over trial

Abstract

To determine the efficacy of the consumption of cranberry juice versus placebo with regard to the presence of in vitro bacterial anti-adherence activity in the urine of healthy volunteers. Twenty healthy volunteers, 10 men and 10 women, were included. The study was a double-blind, randomized, placebo-controlled, and cross-over study. In addition to normal diet, each volunteer received at dinner a single dose of 750 ml of a total drink composed of: (1) 250 ml of the placebo and 500 ml of mineral water, or (2) 750 ml of the placebo, or (3) 250 ml of the cranberry juice and 500 ml of mineral water, or (4) 750 ml of the cranberry juice. Each volunteer took the four regimens successively in a randomly order, with a washout period of at least 6 days between every change in regimen. The first urine of the morning following cranberry or placebo consumption was collected and used to support bacterial growth. Six uropathogenic Escherichia coli strains (all expressing type 1 pili; three positive for the gene marker for P-fimbriae papC and three negative for papC), previously isolated from patients with symptomatic urinary tract infections, were grown in urine samples and tested for their ability to adhere to the T24 bladder cell line in vitro. There were no significant differences in the pH or specific gravity between the urine samples collected after cranberry or placebo consumption. We observed a dose dependent significant decrease in bacterial adherence associated with cranberry consumption. Adherence inhibition was observed independently from the presence of genes encoding type P pili and antibiotic resistance phenotypes. Cranberry juice consumption provides significant anti-adherence activity against different E. coli uropathogenic strains in the urine compared with placebo.

Silver hydrogel urinary catheters: Evaluation of safety and efficacy in single patient with chronic spinal cord injury

“…However, another study did not show such benefits [11]. Although studies examining the use of cranberry supplements to reduce bacteriuria in healthy subjects showed efficacy [12], two small, prospective controlled studies on the use of cranberry supplements in persons with neurogenic bladder dysfunction after SCI did not show any effect on bacteriuria, pyuria, or development of UTIs [13][14]. Different types of catheters with heparin or Teflon ® coatings have also been investigated but have not been clearly shown to be effective.…”

Cranberry products in the prevention of urinary tract infections: examining the evidence

“…6,7,[12][13][14] The anti-adhesive properties of cranberries are effective against the ubiquitous and comparatively benign E. coli with type-1 fimbriae, as well as against p-fimbriated and antibioticresistant E. coli strains. [14][15][16] Incubation of p-fimbriated E. coli with cranberry juice of neutral pH changes the conformation of surface molecules on p-fimbriae within 2 hours profoundly and the adhesion power gets lost. 17 The conclusion of cranberries as harboring potent anti-adhesive compounds other than fructose had fueled a lively research to identify them.…”

“…This is reasonable, as there is strong evidence for cranberry-restricted A-type PAC as anti-adhesive compounds, sufficient evidence for PAC bioavailability in humans [29][30][31] and the preservation of anti-adhesive activity in the urine after oral ingestion. 14,16 Consequently, recently performed clinical trials have employed cranberry products standardized for their PAC, sometimes even for their A-type PAC content to deliver enough bioactivity to probands or patients. However, the ingested dose of PAC/A-type PAC necessary to inhibit bacterial adhesion in the urine is still unknown.…”

Using Atomic Force Microscopy to Measure Anti-Adhesion Effects on Uropathogenic Bacteria, Observed in Urine after Cranberry Juice Consumption

“…We previously reported that AFM adhesion force measurements between uropathogenic E. coli were decreased in the presence of urine from a volunteer who had consumed CJC [18]. In addition, DiMartino et al showed that cranberry juice consumption decreased biofilm development of uropathogenic E. coli in the urine compared with placebo [19,20].…”