Laboratory identification of an infant botulism B case

ObjectiveA laboratory test of the stool sample collected from a suspected infant botulism case in Beijing Children’s Hospital in February 2019 was conducted for the final confirmation.

MethodsThe sample was diluted according to GB 4789.12—2016 for the botulinum toxin identification in animal experiments. The sample was inoculated in enrichment medium to observe its change and inoculated in yolk medium for strain isolation purification. PCR amplification technology was used to amplify 16S rRNA, and the sequences of the target fragments were aligned.

ResultsMice were injected intraperitoneally with dilution of stool sample, and the mice developed shortness of breath, abdominal breathing and died within 4–6 hours, showing typical symptoms of botulism. The typical Clostridium botulinum was isolated on the yolk medium plate, and the spore morphology was observed by gram staining. The gene sequence alignment showed that the sequence of the 16S rRNA shared 99% similarity with that of C. botulinum. Fluorescent quantitative PCR showed that toxin gene B of C. botulinum was positive, and the infant was diagnosed with botulism B.

ConclusionThe test results and diagnosis protocol of this study provide reference for the diagnosis and prevention as well as of clinical identification of botulism B in infants in China.