Cranberry metabolites in urine inhibit bacterial adhesion

Drinking cranberry juice has been shown to prevent urinary tract infections (UTIs) in some clinical studies, but the mechanisms for this benefit remain unclear. It is suggested that cranberry metabolites in urine help prevent bacterial adhesion to uroepithelial cells, which is the first step of infection. We used atomic force microscopy (AFM) to determine the adhesion forces between a clinical strain of E. coli (CFT073) and a silicon nitride probe. Bacteria were bound to a glass slide and incubated in urine for 45 minutes. Urine samples were collected from a volunteer at 0, 2, 4, 6, or 8 hours after consuming 16 oz of either cranberry juice cocktail (CJC) or water. The AFM analysis demonstrated the adhesion forces of bacteria incubated in urine after CJC consumption were lower than those of bacteria incubated in urine after water consumption. whereas bacterial adhesion forces in samples with cranberry metabolites decreased from 1.25 plusmn 0.75 nN (0 hrs after consumption) to 0.38 plusmn 0.2 nN (8 hrs after consumption), adhesion forces in samples collected after water consumption showed no statistically significant temporal difference. These results suggest that cranberry metabolites in urine can inhibit bacterial adhesion for at least 8 hours after consumption.