Alteration of the Murine Gastrointestinal Microbiota by Tigecycline Leads to Increased Susceptibility to Clostridium difficile Infection

Antibiotics can play dual roles inClostridium difficile infection (CDI); antibiotic treatment increases the risk of CDI, and antibiotics are used to treat CDI. The glycylcycline antibiotic tigecycline has broad antimicrobial activity, yet it is rarely associated with the development of CDI, presumably due to its activity againstC. difficile . In this study, we investigated how tigecycline treatment affects the structure of the gut microbiota and susceptibility to CDI by treating mice with tigecycline (n = 20) or saline (n = 8) for 10 days. A sequence analysis of the bacterial 16S rRNA gene amplicons was used to monitor changes in the fecal microbiota. A subset of the mice was followed for 5 weeks after the end of treatment. The remaining mice were challenged withC. difficile strain VPI 10463 spores 2 days after the tigecycline treatment ended. Tigecycline treatment resulted in major shifts in the gut microbiota, including large decreases inBacteroidetes levels and large increases inProteobacteria levels. Mice with tigecycline-altered microbial communities were susceptible to challenge withC. difficile spores and developed clinical signs of severe CDI. Five weeks after the cessation of tigecycline treatment, the recovery of the bacterial community was incomplete and diversity was lower than in the untreated controls. Antibiotics with intrinsic activity againstC. difficile can still alter the microbiota in a way that leads to susceptibility to CDI after discontinuation of the drug. These results indicate that microbiotic dynamics are key in the development of CDI, and a better understanding of these dynamics may lead to better strategies to prevent and treat this disease.