Curcumin: A natural derivative with antibacterial activity against Clostridium difficile

Objectives: The rapid emergence of hypervirulent Clostridium difficile (C. difficile ) isolates and the paucity of effective anti-clostridial antibiotics call for extensive research to identify new treatment options. This study aimed to test the anti-clostridial activity of bioactive extracts of turmeric, which is a natural herb widely known for its profound medicinal properties. Methods: The MICs of turmeric derivatives were determined against 27 C. difficile strains, including hypervirulent (BI/NAP1/027) and clinical toxigenic isolates. Additionally, their ability to inhibit C. difficile toxin production and spore formation was investigated. Furthermore, the safety pro files of turmeric derivatives regarding their effects on human gut micro flora - such as Bacteroides , Lactobacillus and Bifidobacterium - were evaluated. Results: Curcuminoids, the major phytoconstituents of turmeric - including curcumin, demethox- ycurcumin and bisdemethoxycurcumin - inhibited growth of C. difficile at concentrations ranging from 4 to 32 m g/mL. Additionally, curcuminoids showed no negative effect on major populating species of the human gut. Curcumin was more effective than fidaxomicin in inhibiting C. difficile toxin production, but less so in inhibiting spore formation. Conclusion: The findings suggest that curcumin has potential as an anti-clostridial agent. More work is needed to further investigate the ef ficacy of curcumin as a stand-alone drug or as a supplement of current drugs of choice, as it has no antagonistic activities but might overcome their drawbacks. (C) 2019 International Society for Antimicrobial Chemotherapy. Published by Elsevier Ltd.