Differentiating Botulinum Neurotoxin-Producing Clostridia with a Simple, Multiplex PCR Assay

Area of Science:

• Microbiology
• Genomics
• Molecular Biology

Background:

• Diverse Clostridium species produce botulinum neurotoxins (BoNTs), causing botulism.
• Human botulism cases are primarily linked to Clostridium botulinum groups I and II.
• Genomic diversity within BoNT-producing Clostridium species is increasingly recognized.

Purpose of the Study:

• To develop a multiplex PCR assay for differentiating Clostridium botulinum group I, Clostridium sporogenes, and two major subgroups of Clostridium botulinum group II.
• To create a separate PCR assay for detecting the ntnh gene, a component of botulinum neurotoxin gene clusters, and determining cluster type (ha+ or orfX+).

Main Methods:

• In silico analysis of thousands of genome assemblies to identify unique coding region sequences for each species/subgroup.
• Design and validation of PCR primers to amplify identified marker sequences.
• Development and validation of a separate PCR assay for the ntnh gene.

Main Results:

• The multiplex PCR assay successfully assigned 41 tested isolates to their correct species or subgroup.
• The ntnh gene PCR assay accurately determined the presence/absence of botulinum neurotoxin gene clusters and their type (ha+ or orfX+).

Conclusions:

• Novel, rapid, and inexpensive PCR assays enable efficient differentiation of key BoNT-producing clostridia.
• These assays provide valuable information for characterizing isolates from clinical or environmental samples.
• The developed PCR methods support epidemiological studies and identification of bacterial isolates.