Ability of cranberry proanthocyanidins in combination with a probiotic formulation to inhibit in vitro invasion of gut epithelial cells by extra-intestinal pathogenic E. coli

Cranberries and probiotics are individually considered as functional foods. This study evaluated the potential synergy between bioactive proanthocyanidins (c-PAC) derived from cranberries and probiotics on reducing the invasiveness of extra-intestinal pathogenic Escherichia coli (ExPEC) in a cell culture model. ExPEC can be a component of the gut microbiota in healthy individuals, and reducing the invasiveness of ExPEC is a potential means to lessen the risk of subsequent urinary tract infections (UTI), the most common bacterial infections in women. c-PAC (>92 % A-type) concentrations greater than 36 µg c-PAC/mL significantly (p < 0.05) reduced ExPEC invasion, and was not inhibited by the presence of probiotics. Scanning electron microscopy suggests that the mechanism by which c-PAC prevent ExPEC invasion is by cross-linking surface virulence factors. A probiotic blend also significantly reduced invasion, albeit via a different mechanism. This study demonstrated the potential benefit of combining functional A-type c-PAC components in cranberry foods with probiotics.