The role of flagella in Clostridium difficile pathogenicity

• Glycosylation is important for fully functional flagella and complete motility of Clostridium difficile strains
• There is strain-specific involvement of FliC and FliD in adherence and colonisation
• Mutations in fliC and fliD increase toxin gene expression and mutations in fliA and flgE decrease toxin gene expression in C. difficile 630
• There may be a global change in gene expression in C. difficile R20291 flagellar mutants

Clostridium difficile is widely publicised as a problem in the health-care system. Disruption of the normal gut microbiota by antibiotic therapy allows C. difficile to colonise the colon. On colonisation, C. difficile produces two toxins that lead to disease, with symptoms ranging from mild-to-severe diarrhoea, to fulminant and often fatal pseudomembranous colitis (PMC). How C. difficile establishes initial colonisation of the host is an area of active investigation. Recently there has been increased research into the role of C. difficile flagella in colonisation and adherence. Novel research has also elucidated a more complex role of flagella in C. difficile virulence pertaining to the regulation of toxin gene expression. This review focuses on new insights into the specific role of C. difficile flagella in colonisation and toxin gene expression.