Novel avenues for Clostridium difficile infection drug discovery.

Introduction: Clostridium difficile is the etiologic agent of nosocomial and community-acquired diarrhea associated with exposure to antibiotics that disrupt the normal colonic flora. As antibacterials currently used for primary C. difficile infections favor recurrences, new agents able to neutralize the bacterium without affecting the gut microbiota are badly needed. Areas covered: This article investigates the most promising strategies aimed at developing therapies with minimal or no effect on intestinal flora. These therapies include new narrow-spectrum antibiotics and antimicrobial peptides, bacteriophages and phage lysins, virulence-targeting factors such as riboswitch ligands and quorum sensing-interfering factors. It also reviews bacteriotherapy based on probiotics, fecal transplants, and toxin-targeting molecules. Expert opinion: Beyond the development of new antibiotics, virulence-targeting factors or phage cocktails seem promising strategies, which could replace antibiotics avoiding the emergence of resistant strains and the onset of C. difficile infection (CDI). Until broad-spectrum antimicrobials will be in use, C. difficile-specific lytic phages could help to prevent CDI by eliminating C. difficile in patients and in the hospital staff, and for the prevention and treatment of recurrences. Phage therapy is not currently available in Western countries, but, in our opinion, it should have a new chance. Fecal therapy is emerging as a very effective and readily available treatment for recurrences. The shift is from a standardized, drug-based antibacterial therapy toward the forthcoming less expensive and nonpatentable procedures of a more personalized medicine. This will imply profound changes affecting both patient-physician interactions and the current profit-oriented approach to the pharmacologic therapy of infections.