Abstract
Clostridium botulinum produces botulinum neurotoxin (BoNT), which can lead to death if untreated. In the United States, over 90% of wound botulism cases are associated with injection drug use of black tar heroin. We sought to determine the phylogenetic relatedness of C. botulinum isolated from an injection drug use wound botulism case and isolates from endogenous infant botulism cases in Hawaii. Nineteen C. botulinum type B isolates from Hawaii and one type B isolate from California were analyzed by whole-genome sequencing. The botulinum toxin gene (bont) subtype was determined using CLC Genomics Workbench, and the seven-gene multi-locus sequence type (MLST) was identified by querying PubMLST. Mashtree and pairwise average nucleotide identity were used to find nearest neighbors, and Lyve-SET approximated a phylogeny. Eighteen of the isolates harbored the bont/B5 gene: of those, 17 were classified as sequence type ST36 and one was classified as ST104. A single isolate from Hawaii harbored bont/B1 and was determined to belong to ST110, and the isolate from California harbored bont/B1 and belonged to ST30. A tree constructed with Lyve-SET showed a high degree of homology among all the Hawaiian C. botulinum isolates that harbor the bont/B5 gene. Our results indicate that the bont/B-expressing isolates recovered from Hawaii are closely related to each other, suggesting local contamination of the drug paraphernalia or the wound itself with spores rather than contamination of the drug at manufacture or during transport. These findings may assist in identifying interventions to decrease wound botulism among persons who inject drugs.
Highlights
Botulism is a life-threatening disease caused by botulinum neurotoxins (BoNT) which are produced by Clostridium botulinum and rare strains of Clostridium butyricum and Clostridium baratii
Querying the PubMLST database, which generates an allelic profile or seven-gene multi-locus sequence type (MLST) sequence type (ST), revealed that the strains harboring bont/B5 gene were all members of ST-36 except one, which was ST-104
The C. botulinum isolate from Hawaii harboring bont/B1 gene was a member of ST-110, and the C. botulinum isolate from California harboring a bont/B1 gene was a member of ST-30 (Table 1)
Summary
Botulism is a life-threatening disease caused by botulinum neurotoxins (BoNT) which are produced by Clostridium botulinum and rare strains of Clostridium butyricum and Clostridium baratii. There are seven well-characterized serotypes for BoNT (A–G), classically determined by polyclonal. Additional serotypes have been proposed (BoNT/X,/En, and/H) but have not yet reached consensus within the scientific community (Barash and Arnon, 2014; Mansfield et al, 2015; Brunt et al, 2018; Popoff, 2018). BoNT serotypes can have multiple gene subtypes, which are determined by differences in the amino acid sequence. Over 40 subtypes of BoNT serotypes A, B, E, and F have been identified to date (Peck et al, 2017). Serotypes A and B cause most human botulism cases within the United States
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