“…C botulinum consists of 4 groups (I-IV), which sufficiently differ by phylogenetic analysis and in their biochemical properties to be considered as 4 different species. 21 C botulinum group I strains include all 7 subtypes of serotype A (A1-A7), all but 1 subtype of serotype B (B1-B3, B5-B7), most subtypes of serotype F (F1-F5), and serotype H, whereas C botulinum group II strains include only subtype B4 of serotype B, most subtypes of serotype E (E1-E3, E6-E7), and subtype F6 of serotype F. 9,11 In the randomized BIG-IV study by Arnon et al, 13 botulinum toxin type A was found in 60% and type B in 39% of the study patients. However, from the data published, it is not clear how many cases of infant botulism are caused by C botulinum group I and group II strains.…”