Genetic Characterization of Isolated from the First Case of Infant Botulism in Korea.

Botulism is a neuroparalytic disease caused by a neurotoxin produced by . This study aimed to genetically characterize strain isolated from the first case of infant botulism in Korea reported on June 17, 2019. We isolated strain CB-27 from a stool sample of the patient and analyzed the toxin types and toxin gene cluster compositions of the strain using a mouse bioassay, real-time PCR, and genome sequencing. Toxin gene cluster analysis showed that strain CB-27 possesses a neurotoxin type A harboring an unexpressed B gene. Although the nucleotide and amino acid sequences of toxin genes as well as the toxin gene cluster arrangements in strain CB-27 were identical to those of the known strain CDC_69094, the total nucleotide sequences of the toxin gene clusters of CB-27 differed from those of CDC_69094 by 0.47%, indicating genetic diversity of toxin gene clusters of CB-27 among other previously reported strains. To our knowledge, this is the first description of a strain with two separate toxin gene clusters in Korea.