The anti-virulence effect of cranberry active compound proanthocyanins (PACs) on expression of genes in the third-generation cephalosporin-resistant CTX-M-15 associated with urinary tract infection.

Background: Urinary tract infections (UTIs) are one of the most common infections found in humans, with uropathogenic (UPEC) being the most common cause. Prevention of UTI is a major global concern due to its recurrent nature, medical cost, and most importantly, the increased antimicrobial resistance among UPEC. The resistance in UPEC is mainly due to the Extended-Spectrum β-lactamases (ESBL), particularly the CTXM-15 type which is known for its rapid dissemination worldwide. Treatment options for CTXM-15 have become limited over recent years because of their multi-drug resistance, hence anti-virulent strategies based on herbal remedies, have considered as a viable option. The cranberry product, Cysticlean® capsules, contain 240 mg of proanthocyanins (PACs), which have been shown to significantly inhibit adherence, both in vitro and ex vivo, to uroepithelial cells.

Method: In this study, the cephalosporin-resistant isolate NCTC 1553 ( CTXM-15) was analysed by qRT-PCR (quantitative Reverse Transcriptase -Polymerase Chain Reaction) for the expression of virulence factors after treatment with Cysticlean®. qRT-PCR was carried out to detect virulence determinants encoding for toxins SAT, and USP, the iron acquisition system ChuA, the protectins SoxS, KPSM, TraT and RecA, the antibiotic resistance gene CTX-M (encode β-lactamases), and the transporters IdfB and HcaT.

Results: Cysticlean® significantly reduced the expression of all ten selected genes encoding for virulence factors and β-lactamases.

Conclusion: Cranberry product Cysticlean® could represent a practicable alternative option for the prevention of recurrent UTI caused by multi-drug resistant CTXM-15, as the product acts on multiple bacterial targets.