Attenuation of quorum sensing controlled virulence of Pseudomonas aeruginosa by cranberry

BACKGROUND & OBJECTIVES Emergence of antimicrobial resistance in Pseudomonas aeruginosa has led to the search for alternative agents for infections control. Natural products have been a good alternative to present antibiotics. The present study was undertaken to evaluate the effectiveness of cranberry in attenuation of virulence of P. aeruginosa in experimental urinary tract infection (UTI) in mouse model. Efforts were also directed to explore the action of cranberry towards virulence of P. aeruginosa through quorum sensing (QS) inhibition. METHODS Efficacy of cranberry was evaluated in an experimental UTI mouse model and on production of QS signals, alginate, pyochelin, haemolysin, phospholipase-C, cell-surface hydrophobicity, uroepithelial cell-adhesion assay and biofilm formation by already standardized methods. RESULTS Presence of cranberry showed significant decline in the production of QS signals, biofilm formation and virulence factors of P. aeruginosa in vitro (P<0.001). Further, cranberry was found to be useful in prevention of experimental UTI in mouse model as indicated by reduced renal bacterial colonization and kidney tissues destruction. INTERPRETATION & CONCLUSIONS The findings of the present study indicated that cranberry inhibited QS and hence elaboration of virulence factors of P. aeruginosa. It also affected the adherence ability of this pathogen. This approach can lead to the discovery of new category of safe anti-bacterial drugs from dietary sources such as cranberry with reduced toxicity without the risk of antibiotic resistance.