Regarding binary toxin of C. difficile

So far Toxin A and Toxin B were known clinically significant for C.Diff. but recently some deadly strains of C. difficile are found to produce an additional toxin called binary toxin. This was first reported in 1988 but never considered clinically significant. Interestingly, binary toxin producers make up the majority of the C. difficile strains isolated in the recent large outbreaks. Also, a correlation between binary toxin production and severity of dirrhea has been demonstrated, and more community-acquired C. difficile-associated diarrhoea was found to be caused by binary toxin producers. The presence of the binary toxin in Clostridium difficile infection contributes to a marked increase in the risk of death, researchers reported. But still, it remains unclear whether the binary toxin itself causes increased virulence or is a marker for virulence.