Study Title:

Cranberry and Urinary Tract Infections

Study Abstract

ABSTRACT Previous clinical research has suggested that the consumption of cranberry products prevents the adhesion of Escherichia coli to uroepithelial cells by causing changes in bacterial fimbriae. Atomic force microscopy was used to probe the adhesion forces between E. coli (nonfimbriated strain HB101 and the P-fimbriated variant HB101pDC1) and a model surface (silicon nitride), to determine the effect of growth in cranberry products on bacterial adhesion. Bacteria were grown in tryptic soy broth supplemented with either light cranberry juice cocktail (L-CJC) or cranberry proanthocyanidins (PACs). Growth of E. coli HB101pDC1 and HB101 in L-CJC or PACs resulted in a decrease in adhesion forces with increasing number of cultures. In a macroscale bacteria–uroepithelial cell adhesion assay a decrease in bacterial attachment was observed for E. coli HB101pDC1 grown in L-CJC or PACs. This effect was reversible because bacteria that were regrown in cranberry free medium regained their ability to attach to uroepithelial cells, and their adhesion forces reverted to the values observed in the control condition. Exposure to increasing concentrations of L-CJC resulted in a decrease of bacterial attachment to uroepithelial cells for the P-fimbriated strain after L-CJC treatment (27% by weight) and after PACs treatment (345.8 g/mL). Cranberry products affect the surface properties, such as fimbriae and lipopolysaccharides, and adhesion of fimbriated and nonfimbriated E. coli. The concentration of cranberry products and the number of cultures the bacteria were exposed to cranberry determines how much the adhesion forces and attachment are altered.

From press release:

Chemicals present in cranberries—and not the acidity of cranberry juice, as previously thought—prevent infection-causing bacteria from attaching to the cells that line the urinary tract, as documented in a report published in Journal of Medicinal Food.

Urinary tract infections (UTIs) burden the healthcare system with more than $2 billion in treatment costs each year and are a common problem in patients with a urinary catheter in place. Adhesion of E. coli bacteria to cells lining the urinary tract is the first step in the development of a UTI. Chemicals found in cranberry products called proanthocyanidins (PACs) prevent E. coli, which is the cause of about 85% of UTIs and 90% of cases of acute pyelonephritis, from adhering to these urinary tract epithelial cells by affecting the surface properties of the bacteria.

Paola Pinzón-Arango, Yatao Liu, and Terri Camesano, from Worcester Polytechnic Institute, in Massachusetts, exposed E. coli grown in culture to either light cranberry juice cocktail or cranberry PACs and measured the adhesion forces between the bacteria and a silicon surface using atomic force microscopy. They demonstrated that the longer the bacteria were exposed to either the cranberry juice or the PACS the greater the decrease in bacterial attachment. In the article entitled, "Role of Cranberry on Bacterial Adhesion Forces and Implications for Escherichia coli—Uroepithelial Cell Attachment," the authors also concluded that this effect was reversible, and that bacteria regrown in an environment without cranberry juice or PACS regained the ability to attach to the model surface.

"Cranberries, one of only three species of fruits native to North America, has a long history of medicinal food use. Native Americans used the fruit for the treatment of bladder and kidney ailments hundreds of years ago. The article by Camesano and co-workers is a milestone in the understanding of its mechanism of action," says Sheldon S. Hendler, PhD, MD, Co-Editor-in-Chief of the Journal, and Clinical Professor of Medicine, University of California, San Diego.

Study Information

Paola A. Pinzón-Arango, Yatao Liu, and Terri A. Camesano
Role of Cranberry on Bacterial Adhesion Forces and Implications for Escherichia coli–Uroepithelial Cell Attachment.
Journal of Medicinal Food.
2009 March
Worcester Polytechnic Institute, in Massachusetts.

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