Fidaxomicin successfully treated simulated primary and recurrent CDI. Fidaxomicin was superior to metronidazole in reducing CD TVC and SP, and superior to vancomycin in reducing SP without recurrence of vegetative cell growth. Fidaxomicin, but not vancomycin or metronidazole, persisted in the gut model for >20 days after instillation.

A clinically reflective model of the human colon was used to investigate the effects of the broad-spectrum antibiotic omadacycline on the gut microbiome and the subsequent potential to induce simulated Clostridium difficile infection (CDI). Triple-stage chemostat gut models were inoculated with pooled human fecal slurry from healthy volunteers (age, ≥60 years).

Both NVB302 and vancomycin were effective in treating simulated CDI in an in vitro gut model. C. difficile spore recrudescence was not observed following successful treatment with either NVB302 or vancomycin. NVB302 displayed non-inferiority to vancomycin in the treatment of simulated CDI, and had less deleterious effects against B. fragilis group. NVB302 warrants further clinical investigation as a potentially novel antimicrobial agent for the treatment of CDI.

Cadazolid activity was greater than other tested antimicrobials against 100 C. difficile strains. Cadazolid effectively treated simulated CDI in a gut model, with limited impact on the enumerated gut microflora and no signs of recurrence or emergence of resistance within the experimental timeframe.

rCDI is a significant challenge for healthcare professionals, requiring a multifaceted approach; optimized infection control to minimize reinfection; C. difficile-targeted antibiotics to minimize dysbiosis; and gut microflora restoration to promote colonization resistance. These elements should be informed by our understanding of the microbiologic factors involved in both C. difficile itself and the gut microbiome.