601. Antimicrobial activity of beta-bio45% hops extract against Clostridium difficile NAP1/027
Session: Poster Abstract Session: Novel Antimicrobial Agents
Friday, October 21, 2011
Room: Poster Hall B1
Background: Clostridium difficile is the main aetiologic agent of hospital acquired diarrhea in industrialized countries.  A highly virulent strain, C. difficile NAP1/027 has emerged in the last decade causing epidemics in North America and Europe.  Metronidazole and vancomycin are currently the antibiotics used to treat Clostridium difficile infections (CDI) but treatment failures and relapses have been reported.  Thus, new therapeutic options are greatly needed.  Humulus lupulus (hops) bitter acids are used to prevent bacterial overgrowth in the brewing industry.  They have been shown to prevent Clostridium perfringens outbreaks in chicken.  We tested the in vitro activity of Humulus lupulus (hops) CO-2 extract against Clostridium difficile NAP1/027.

Methods: Four different Humulus lupulus beta-acid extracts were purified by C0-2 extraction and obtained commercially (Hopsteiner inc).  C. difficile NAP1/027 was plated on a BHB agar containing 6mm wells.  Vancomycin in addition to pure and diluted extracts were added to the wells.  The plates were incubated in anaerobic conditions for 48h and growth inhibition zones were measured. 

Results: All extracts showed antibacterial activity against C. difficile NAP1/027.  Beta-bio45% extract (BB45) had the strongest antibacterial activity amongst the four beta-acid extracts.  It maintained strong antibacterial activity against Clostridium difficile at dilutions of 1/20 000 with inhibition zones surpassing that of vancomycin. 

Conclusion: BB45% has a strong in vitro antibacterial activity against C. difficile NAP1/027.  Further studies are required to document in vivo activity and safety in treatment or prevention of CDI. 

Subject Category: A. Antimicrobial agents and Resistance

Mirabelle Kelly, MD, Microbiology, Hôpital Jean-Talon, Montréal, QC, Canada and Fortier Louis-Charles, PhD, Microbiology , University of Sherbrooke, Sherbrooke, QC, Canada


M. Kelly, None

F. Louis-Charles, None

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