Question
Mycetism
Answer
Mycetism (mushroom poisoning) refers to the toxic clinical syndrome that follows ingestion of poisonous wild mushrooms, with the specific clinical picture and severity varying markedly depending on the toxin(s) present in the ingested species and the time to symptom onset.
Classification by onset and toxin type:
- Rapid-onset (within 2 hours) syndromes — generally caused by toxins producing milder, self-limiting gastrointestinal or neurological symptoms (e.g., muscarine-containing species causing a cholinergic syndrome — salivation, lacrimation, sweating, bradycardia; or species causing gastrointestinal irritant symptoms alone) — the rapid onset itself is often reassuring, generally correlating with a less life-threatening toxin.
- Delayed-onset (6–24 hours or later) syndromes — the more dangerous category, since the delay allows significant toxin absorption before treatment is sought, and is classically associated with the most lethal mushroom poisoning: Amanita phalloides (“death cap”) and related Amanita species, containing amatoxins (cyclic peptides), which inhibit RNA polymerase II, halting cellular protein synthesis — causing a biphasic illness: an initial gastrointestinal phase (severe vomiting/diarrhoea, 6–24 hours after ingestion), an apparent (deceptive) clinical improvement, followed by progressive, often fatal fulminant hepatic and renal failure over the following days, since amatoxin is directly hepatotoxic and undergoes enterohepatic recirculation, prolonging exposure.
Clinical significance: the delayed-onset pattern is a critical clinical teaching point — a patient who appears to improve after initial gastrointestinal symptoms following wild mushroom ingestion may in fact be entering the silent phase preceding severe hepatotoxicity, and should not be falsely reassured or discharged without close monitoring/specific consideration of amatoxin poisoning.
Management: largely supportive (aggressive fluid/electrolyte management, activated charcoal if given early); specific measures for amatoxin poisoning can include silibinin, N-acetylcysteine, and, in severe cases, liver transplantation for fulminant hepatic failure; species identification of the ingested mushroom (if a sample is available) is valuable in guiding management and prognosis.