In-depth genetic analysis of Clostridium difficile PCR-ribotype 027 strains reveals high genome fluidity including point mutations and inversions

Previously, we demonstrated that the recently evolved PCR-ribotype 027 hypervirulent Clostridium difficile strain (R20291) has acquired five genetic regions compared to the historic 027 counterpart strain (CD196), that may in part explain phenotypic traits relating to survival, antimicrobial resistance and virulence. Closer scrutiny of the three genome sequences reveals that, in addition to gene gain/loss, point mutations and inversions appear to have accumulated. Inversions are located upstream of potential coding sequences and could affect expression of these. C. difficile has a highly fluid genome with multiple mechanisms to modify its genetic content and is continuing to evolve in our hospitals influenced by environmental changes and human activity.