Diversity of Group I and II Clostridium botulinum Strains from France Including Recently Identified Subtypes.

In France, human botulism is mainly food-borne intoxication, whereas infant botulism is rare. A total of 99 group I and II Clostridium botulinum strains including 59 type A (12 historical isolatesj1947-19611, 43 from Francej1986-20131, 3 from other countries, and 1 collection strain), 31 type B (3 historical, 23 recent isolates, 4 from other countries, and 1 collection strain), and 9 type F (5 historical, 3 isolates, and 1 collection strain) were investigated by botulinum locus gene sequencing and multilocus sequence typing analysis. Historical C. botulinum A strains mainly belonged to subtype Al and sequence type (ST) 1, whereas recent strains exhibited a wide genetic diversity: subtype Al in ortX or ha locus, A1 (B), A1 (F), A2, A2b2, A5(B2')A5(B31), as well as the recently identified A7 and A8 subtypes, and were distributed into 25 STs. Clostridium botulinum Al (B) was the most frequent subtype from food-borne botulism and food. Group I C. botuiinum type B in France were mainly subtype B2 (14 out of 20 historical and recent strains) and were divided into 19 STs. Food-borne botulism resulting from ham consumption during the recent period was due to group II botulinum B4. Type E botulism is rare in France, 5 historical and 1 recent strains were subtype E3. A subtype El 2 was recently identified from an unusual ham contamination. Clostridium botulinum strains from human botulism in France showed a wide genetic diversity and seems to result not from a single evolutionary lineage but from multiple and independent genetic rearrangements.