Effect of antibiotic treatment on the formation of non-spore Clostridium difficile persister-like cells

Background: The spore is the virulence factor identified to be involved in the recurrence of the disease caused by Clostridium difficile. Objectives: To demonstrate that lethal antibiotic concentrations induce the appearance of C. difficile persisterlike non-spore cells. Methods: C. difficile and derivative spo0A mutant strains were tested for their susceptibility to antibiotics, as determined using an agar dilution method. Persister-cell generation was determined for all strains using up to 10× the MIC of every antibiotic for up to 6 days. Results: Using up to 10× the MIC of every antibiotic, we were able to induce the appearance of persister-like behaviour since biphasic killing curves could be observed in response to treatment antibiotics. Conclusions: To the best of our knowledge, this work provides, for the first time, experimental evidence of the appearance of C. difficile persister-like cells, opening a new research avenue in the pathogenesis of this nosocomial pathogen.