Bacterial Anti-adhesion and Antibiotic Resistance

Early theories regarding the mechanism of action of cranberry juice cocktail in helping prevent UTIs involved acidification of the urine. However, that has not been confirmed, and evidence has been accumulating instead which indicates that natural components in the fruit act to inhibit the adhesion of infection-causing E. coli bacteria within the urinary tract. The compounds responsible have been identified by Howell et al. as proanthocyanidins (PACs), or condensed tannins. While many fruits contain similar compounds, thus far only the PACs of cranberries and blueberries, which are botanically related species, have been shown to exhibit this effect. More detailed work presented in April 2002 showed that of tests with cranberries, grapes, apples, tea, and chocolate, only cranberries exhibited this ability to block bacteria from sticking.

While cranberry is perhaps best known for its effect on urinary tract health, newer research indicates that it may act elsewhere in the body against other bacteria as well. The adhesion of the different types of bacteria that cause both stomach ulcers, and periodontal gum disease, have been shown to be inhibited in the presence of cranberry, and it is likely that others susceptible bacteria will be found as well.

It is likely that the anti adhesion effect may have far reaching implications. Not only may regular consumption of cranberry products help maintain health, but in the process will reduce the number of infections in a given population, and thereby the doses of antibiotics which are needed. It is becoming increasingly clear that a reduction in general antibiotic use also reduces the likelihood of the bacteria becoming resistant to those very same antibiotics, which is a public health problem of global proportions.