The study aimed to identify the Clostridium botulinum (C. botulinum) source involved in a food poisoning case in Kunming and analyze its molecular characteristics. To achieve this, the researchers examined various samples, including pickled pig liver consumed by three patients, hospital vomit from a deceased patient, and household waste mixed with vomit. Using a combination of enrichment culture, microscopic examination, and real-time quantitative PCR, they confirmed the presence of C. botulinum, specifically type E botulinum toxin, and designated the strain as KM001. This marked the first report of type E botulinum toxin poisoning in the region. The researchers further analyzed the genomic sequence of the KM001 strain using second and third-generation sequencing, which revealed a genome size of 3,713,470 base pairs. The genome contained 1,840 single genes assigned to 44 KEGG pathways, as indicated by KEGG annotation. Whole-genome sequencing also revealed genetic diversity among toxin gene clusters, with the KM001 strain showing 94.76% homology to C. botulinum E3 strain (Alaska E43) and 93.65% homology to C. botulinum B strain (Eklund 17B, NRP). The evolutionary analysis, which incorporated complete genomes of foodborne and environmental C. botulinum strains worldwide, showed that the KM001 strain had a stronger phylogenetic affinity to other type E strains. The study's findings provide valuable insights into the gene function, virulence, and evolutionary relationships of C. botulinum, which are crucial for predicting infection risks and implementing effective control measures. However, the study notes that further research is needed to examine the antimicrobial resistance of C. botulinum and its interactions with other microorganisms, which are important aspects not addressed in this study. Overall, the study contributes to the documentation of botulinum toxin incidents in Yunnan, China, and highlights the importance of continued research into the genetic relationships and evolutionary pathways of different C. botulinum strains.

Link: https://pubmed.ncbi.nlm.nih.gov/40050811/