Researchers have found a new use for cranberries in combating bacterial infections, including preventing bacterial colonization in urinary catheters.
Two studies published in the Canadian Journal of Microbiology and Colloids and Surfaces B: Biointerfaces revealed that cranberry powder can inhibit the bacterium Proteus mirabilis, a bug commonly found in complicated urinary tract infections (UTIs).
The research, by chemical engineering scientists at Montreal's McGill University, showed that increasing the concentration of cranberry powder reduced the bacteria's production of urease, an enzyme that helps the infection to spread.
Previous studies from the same McGill laboratory found that cranberry materials can limit the movement of bacteria found in UTIs. In an analysis of E. coli found in the bladder, their work showed that exposure to cranberry extracts caused decreased expression of the gene that encodes for the bacterium's flagellar filament.
The researchers say their work is significant as the movement of bacteria is a key mechanism for the spread of infection. The bacteria "swim" in order to spread in the urinary tract and escape the immune system.
Professor Nathalie Tufenkji, study leader, says:
"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.
"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."
Previous studies also provide evidence that cranberry derivatives are effective against UTIs. Research from the American Chemical Society revealed that cranberry juice is effective at stopping E. coli sticking to other bacteria, making it easier to be flushed away from the urinary tract.
However, research published in The Cochrane Library last year contradicted evidence that cranberries are effective in the prevention of UTIs. The study suggested that cranberry juice is effective only in women suffering from recurrent infections, and did not prove any more effective in preventing UTIs compared with other methods of treatment.
But this most recent research revealed that cranberry-enriched silicone substrates disabled the spread of Proteus mirabilis.
This could lead to cranberry extracts being used to limit the spread of germs in implantable medical devices such as catheters, the researchers say.
Tufenkji adds: "Based on the demonstrated bioactivity of cranberry, its use in catheters and other medical devices could someday yield considerable benefits to patient health."