Clostridioides difficile toxins: mechanisms of action and antitoxin therapeutics

. Author manuscript; available in PMC: 2022 Nov 1.

Published in final edited form as: Nat Rev Microbiol. 2021 Nov 26;20(5):285–298. doi: 10.1038/s41579-021-00660-2

Clade	Representative STs (RT, TcdB variant, receptor and disease severity)	Refs
C1: TcdA⁺TcdB⁺CDT⁺ TcdA⁺TcdB⁺CDT⁻ TcdA⁻TcdB⁺CDT⁻ TcdA⁻TcdB⁻CDT⁻	ST54 (RT630): TcdB1 variant; binds CSPG4 and FZD; induces severe disease ST2, ST7, ST46, ST48, ST145 (RT087): TcdB1 variant; binds CSPG4 and FZD; induces severe disease	^{32,34,153,165–167}
C2: TcdA⁺TcdB⁺CDT⁺	ST1 (RT027): TcdB2 variant; binds CSPG4; induces strong oedema ST1 (RT036): TcdB4 variant; binds FZD or CSPG4 weakly; induces mild disease	^32,34,168
C3: TcdA⁺TcdB⁺CDT⁺	ST5 (RT023)	¹⁶⁹
C4: TcdA⁻TcdB⁺CDT⁻	ST37 (RT017): TcdB3 variant; binds FZD; induces severe inflammation	¹⁷⁰
C5: TcdA⁺TcdB⁺CDT⁺ TcdA⁻TcdB⁺CDT⁺	ST11 (RT078)	^152,171
CI: TcdA⁻TcdB⁺CDT⁻	ST200, ST311, ST620	¹⁵⁵
CII: TcdA⁻TcdB⁺CDT⁻	ST181, ST314, ST360	¹⁵⁵
CIII: Variable	ST342, ST343, ST369	¹⁵⁵

This is not an exhaustive list, and some STs may differ in their characteristics. CDT, C. difficile transferase; CSPG4, chondroitin sulfate proteoglycan 4; FZD, Frizzled; RT, ribotype.