Whole-genome sequencing completes the traceability of a type B1 botulinum toxin poisoning incident.

OBJECTIVES

To complete the traceability from patient to food using single nucleotide polymorphism (SNP)-based clustering analysis technology after whole-genome sequencing in botulinum toxin poisoning incidents.

METHODS

Botulinum toxin in the patient's blood and urine was detected. Real-time polymerase chain reaction was used for preliminary screening and typing of Clostridium botulinum toxin genes in the patient's feces and all suspicious samples after epidemiological investigation. Then antitoxin serum was administered to the patient within 2 hours clinically. Finally, SNP-based clustering analysis achieved traceability from patient to food at the genetic level.

RESULTS

Botulinum toxins in the patient's blood and urine were positive, confirming foodborne botulinum toxin poisoning. Virulence genes of type B were detected in the patient's feces and the homemade sufu sample. The mouse intraperitoneal injection test confirmed that the homemade sufu contained botulinum toxin. The isolated Clostridium botulinum showed the typical tennis racket-shaped morphology under the microscope. The multilocus sequence typing type was ST115, and the neurotoxin (BoNT) was type B1. After whole-genome sequencing, SNP-based clustering analysis found that the number of differing SNP sites between strains of Clostridium botulinum isolated from feces and sufu was 0.

CONCLUSION

This technology traced the etiological food and excluded other factors unrelated to the poisoning incident, thereby preventing the recurrence of similar poisoning incidents caused by the same batch of food.