Cranberry Effects On UTI-Causing Bacteria
July 16, 2013

How Does The Cranberry Affect The Bacteria That Cause Urinary Tract Infections?

April Flowers for - Your Universe Online

For over 100 years, the consumption of cranberry products has been anecdotally associated with prevention of urinary tract infections (UTIs). Scientists have long questioned if this is myth or scientific fact.

Some recent studies have suggested cranberries prevent UTIs by hindering bacteria from sticking to the walls of the urinary tract. Phytochemicals known as proanthocyanidins (PACs) create this hindrance, but the mechanism by which cranberry materials may alter bacterial behavior have not been fully understood until now.

A research team from McGill University's Department of Chemical Engineering is shedding light on the biological mechanisms by which cranberries might impart protective elements against infections. Nathalie Tufenkji, Associate Professor in the Department of Chemical Engineering, spearheaded two studies that add new evidence of cranberries' effects on UTI-causing bacteria, as well as highlighting the potential for cranberry derivatives to be used to prevent bacterial colonization in medical devices such as catheters.

In the first study, published in the Canadian Journal of Microbiology, Tufenkji and her team report cranberry powder can inhibit the ability of Proteus mirabilis to swarm on agar plates and swim within the agar. P. mirabilis is a bacterium frequently implicated in complicated UTIs. The team's experiments also reveal increasing concentrations of cranberry powder reduce the production of urease by the bacteria. Urease is an enzyme that contributes to the virulence of infections.

The results of this study build upon previous work by the same McGill lab. The previous study showed cranberry materials hinder movement of other bacteria involved in UTIs. The lab performed a genome-wide analysis of an uropathogenic E. coli, which revealed that expression of the gene that encodes for the bacteria's flagellar filament was decreased in the presence of cranberry PACs.

These findings have significant implications because bacterial movement is a key mechanism for the spread of infection, as infectious bacteria literally swim to disseminate in the urinary tract and to escape the host immune response.

"While the effects of cranberry in living organisms remain subject to further study, our findings highlight the role that cranberry consumption might play in the prevention of chronic infections," Tufenkji says. "More than 150 million cases of UTI are reported globally each year, and antibiotic treatment remains the standard approach for managing these infections. The current rise of bacterial resistance to antibiotics underscores the importance of developing another approach."

In the second study, published online in the journal Colloids and Surfaces B: Biointerfaces, Tufenkji worked with McGill professor Showan Nazhat, a biomaterials expert at the Department of Mining and Materials Engineering. The findings of this study reveal cranberry-enriched silicone substrates impaired the spread of Proteus mirabilis. These results point to potential use for cranberry derivatives to hinder the spread of germs in implantable medical devices such as catheters, which are frequently implicated in UTIs.

"Based on the demonstrated bioactivity of cranberry, its use in catheters and other medical devices could someday yield considerable benefits to patient health," Tufenkji says.

The two studies were funded by the Natural Sciences and Engineering Research Council of Canada, the Canada Research Chairs program, the Wisconsin Cranberry Board, the Cranberry Institute, the Fonds quebecois de la recherche sur la nature et les technologies, and the Fonds de la recherche en sante du Quebec.