Molecular identification of Amanita ibotengutake from patient vomit specimens in mushroom poisoning

Mushroom poisoning remains a global public health challenge, with morphological identification accuracy limited to 17%. This study aimed to demonstrate molecular identification from vomit specimens in a patient with mushroom poisoning. Following a mushroom poisoning incident in Yamagata Prefecture, Japan (September 2018), we collected four vomit specimens from a female patient. Deoxyribonucleic acid analysis targeting the internal transcribed spacer region using polymerase chain reaction and sequencing was performed on three of four specimens, while liquid chromatography-tandem mass spectrometry or toxin quantification was conducted on all four specimens. Species identification was conducted through sequence homology analysis. Polymerase chain reaction amplification of the 185 base pair target sequence was successful from three vomit specimens collected 7 h post-ingestion, yielding identical sequences. Sequence analysis identified Amanita ibotengutake (100% homology), contradicting the initial morphological identification of Amanita pantherina. Liquid chromatography-tandem mass spectrometry detected a total of 0.053 mg ibotenic acid and 0.0043 mg muscimol in vomit specimens, consistent with the patient's neurological symptoms. The discrepancy between morphological (Amanita pantherina) and molecular (Amanita ibotengutake) identification demonstrates limitations of conventional methods, particularly significant as these species were considered identical until 2002. Successful deoxyribonucleic acid amplification 7 h post-ingestion, despite technical challenges from gastric degradation, suggests clinical feasibility. This integrated molecular-toxicological approach strengthens scientific understanding of species-specific toxicities and contributes to improved epidemiological investigation of mushroom poisoning. We report the successful molecular identification from patient vomit specimens in a patient with mushroom poisoning. Although limited to a single case, this methodology may contribute to strengthening mushroom poisoning reports in the scientific literature to improve understanding of species-specific toxicities. Further validation in additional cases is needed for broader scientific applications.