Clostridioides difficilebinary toxin CDT induces biofilm-like persisting microcolonies

Abstract

SUMMARYClinical symptoms ofClostridioides difficileinfection (CDI) range from diarrhea to pseudomembranous colitis. A major challenge in managing CDI is the high rate of relapse. Several studies correlate production of CDT binary toxin by clinical strains ofClostridioides difficilewith higher relapse rates. Although the mechanism of action of CDT on host cells is known, its exact contribution to CDI is still unclear. To understand the physiological role of CDT during CDI, we established two hypoxic relevant intestinal models, Transwell and Microfluidic Intestine-on-Chip systems. Both were challenged with the epidemic strain UK1 CDT+and its isogenic CDT-mutant. We report that CDT binary toxin induces mucin-associated microcolonies that increaseC. difficilecolonization and display biofilm-like properties by enhancingC. difficileresistance to vancomycin but not to fidaxomicin, a biofilm disrupting antibiotic. Importantly, biofilm- like CDT-dependent microcolonies were also observed in the caecum and colon of infected mice. Hence, our study shows that CDT toxin induces biofilm-like microcolonies, increasingC. difficilecolonization and persistence.