Scientists have demonstrated that cranberry proanthocyanidin (cPAC) prevents the evolution of resistance to tetracycline in pathogenic bacteria, rescues antibiotic efficacy against antibiotic‐exposed cells, and represses biofilm formation.
The bacteria studied were those responsible for urinary tract infections, pneumonia, and gastro-enteritis (Proteus mirabilis, Pseudomonas aeruginosa, and Escherichia coli).
The results show that cPAC has a potentiating effect, both in vitro and in vivo (insect), on a broad range of antibiotic classes against pathogenic E. coli, Proteus mirabilis, and P. aeruginosa.
The researchers found that cPAC acts by repressing two antibiotic resistance mechanisms; selective membrane permeability and multidrug efflux pumps. Failure of cPAC to potentiate antibiotics against efflux pump‐defective mutants demonstrates that efflux interference is essential for potentiation, they said.
If confirmed by further animal testing, cPAC could be used to potentiate antibiotics and thus improve treatment outcomes and help mitigate the growing threat of antimicrobial resistance, the study authors said.
“These are really exciting results," said study co-author Prof Éric Déziel. "There are several different kinds of proanthocyanidins, and they may work together to deliver this outcome. We'll need to do more research to determine which ones are most active in synergy with the antibiotic."
The study appears in the journal Advanced Science.