Evaluating the anti-bacterial and anti-virulence factors activity of Vaccinium macrocarpon (Cranberry) extract against clinical isolates of pseudomonas aeruginosa

Abstract

P. aeruginosa produces a range of metabolites among them pyocyanin, protease and hemolysin. In our study, the antibacterial and antivirulence factors activity of the methanolic extract of cranberry was investigated against 20 clinical isolates of P. aeruginosa by using two-fold dilution method (2FD). Thecranberry extract exhibited good antibacterial activity at MIC 0.1125-0.0562 mg/ml and good Inhibitory effect for pyocyanin, hemolysin and protease at sub- MIC 0.00351 mg/ml. So, this extract is identified as a potential anti-virulence strategy. Then, the effectiveness of cranberry extract against pyocyanin was detected by real-time PCR (qPCR) for two bacterial isolates, the result revealed the extract has an inhibitory effect on the expression of the Pyocyanin gene phzM (by 0.5-fold lesser than the untreated sample) for first isolate and 5-fold higher than an untreated sample) for the second isolate, although this isolate was lost its ability to produce pyocyanin phenotypically. GC-MC test revealed the Cranberry extract contains strong anti-bacterial as well as anti-virulence factor compounds.