Cranberry extract with enhanced bactericidal activities against uropathogenic Escherichia coli within one minute of treatment

Cranberry has been widely utilized as a popular botanical dietary supplement to prevent urinary tract infection. The study aims to evaluate the enhanced bactericidal activities of cranberry against uropathogenic Escherichia coli (UPEC) by adding a small quantity of naturally derived antimicrobials. The antibacterial effect was examined with cranberry extract alone (15 and 20%), three kinds of medium-chain fatty acids alone (caprylic, capric, and lauric acid; 0.05–1.0 mM), essential oils alone (carvacrol and thymol; 0.5–1.0 mM), and cranberry extract containing medium-chain fatty acids or essential oils at 37 °C for 1 min. The survivors were remarkably reduced with cranberry extract containing any of the antimicrobials. For example, cranberry extract (15 and 20%) with 1.0 mM of each caprylic acid, lauric acid, and carvacrol resulted in the complete eradication of UPEC (7.55 log reduction). Flow cytometry analysis of UPEC cells exposed to combined treatment showed clear membrane disruption and cell death (>95% of damage). Adding antimicrobials to cranberry extract did not affect (P > 0.05) the characteristics of the cranberry extract (Color, °Brix, pH). The present method may be more acceptable to consumers, who tend to avoid products containing synthetic chemicals and prefer the use of natural agents.