Mushroom Poisoning

Introduction

• Typically benign self-limiting GI upset through to lethal hepatotoxicity
• Cyclopeptide hepatotoxic Amanita phalloides toxicity is extremely rare in Aus with almost all cases isolated to ACT
• Must consider this if GI symptoms develop >6 hours after mushroom intake, especially if grown wild in Canberra
• Whether mushroom is cooked also comes into risk assessment

Toxins

• Muscarine causes cholinergic syndrome through peripheral muscarinic agonism (does not stimulate nicotinic receptors and does not cross BBB)
• Muscimol (resembles GABA) and stimulates GABA receptors to cause glutaminergic toxicity 
• Ibotenic acid (resembles glutamic acid) stimulates central glutamine receptors
• Gyromitrin activated to monomethylhydrazine and inhibits pyridoxine-dependent synthesis of GABA
• Psilocybin resembles LSD
• Coprine inhibits acetaldehyde dehydrogenase
• Amatoxins (alpha-amanitin) inactivate RNA polymerase II and inhibit protein synthesis

Early onset (<6 hours)

• Miscellaneous GI: Onset 30min-3 hours, resolves 6-24 hours
• Cholinergic: Vomiting, diarrhoea, lacrimation, salivation, urinary incontinence, bronchorrhoea, bronchospasm, miosis. Onset 30 min to 2 hours.
• Hallucinogenic: Ataxia, anxiety, mydriasis, tachycardia, dyskinesia, delirium, hallucinations. Onset within minutes and resolves over 4-6 hours
• Disulfiram-like: Nausea, vomiting, tachycardia, flushing, sweating, chest pain. Onset following ethanol consumption within 7 days
• Glutaminergic: Dizziness, drowsiness, delirium, dysphoria, hallucinations, myoclonus, hyperreflexia, seizures. Onset 30 min to 2 hours. 

Early onset (<6 hours)

• Epileptogenic
  • Seen with Gyromitrin toxin with early GI symptoms, headache, ataxia, fatigue, nystagmus, tremor, vertigo and rarely seizures
  • May then show delayed transaminitis (onset at 2-3 days) and delayed haemolysis and methaemoglobinaemia (1-3 days after hepatic injury)
• Immunohaemolytic
  • Seen with Paxillus species with early GI upset followed in days with haemolytic anaemia, haemoglobinuria, immune-complex nephritis and acute renal failure
• Pneumonic
  • Seen with inhalation of dried Lycoperdonosis spores
  • Early nausea, vomiting, rhinitis then acute bronchopneumonia within days

Delayed onset (6-24 hours)

• Seen with three classes of cyclopeptide (Amatoxins, Phallatoxins and Virotoxins)
  • Asymptomatic for 6-18 hours 
  • GI within 6-24 hours
  • Transient clinical improvement then asymptomatic rise in transaminases over 18-36 hours
  • Then progressive hepatic failure, kidney injury, coagulopathy and MODS over 1-7 days with 30% mortality
  • Recovery in survivors >7 days
• Also erythromelalgia due to acromelic acids
  • Seen with onset over 24-72 hours of burning pain, redness, oedema of feet, exacerbated by heat and relieved by cold
  • Resolves over 8 days to 5 months

Greatly delayed onset (>24 hours)

• Nephrotoxic
  • Seen with Orellanine with onset over 24-36 hours of anorexia, headache, nausea, vomiting, abdo pain and flank pain with interstitial nephritis and acute kidney injury + severe burning thirst
• Rhabdomyolysis
  • Seen with Tricholoma and Russula species
  • Onset over 24-72 hours of fatigue, myalgias, muscle weakness and rarely myocarditis

Management

• Supportive care, rehydration, general seizure/airway management
• Activated charcoal IF delayed onset of GI symptoms >6 hours
• Examination of any available mushrooms by a mycologist is useful if cyclopeptides is considered likely
• Meixner test
  • HCl added to sample of offending mushroom and if blue colour change occurs this suggests presence of cyclopeptide hepatotoxins
  • LFT should be monitored for 24-48 hours if hepatotoxins considered likely
  • Electrolytes and creatinine monitored if significant GI losses
• Multiple dose activated charcoal if cyclopeptide hepatotoxin suspected as amatoxin undergoes enterohepatic circulation

Management

• Antidotes
  • If delayed GI symptoms OR rising transaminases
    • NAC as per protocol
    • MDAC as per protocol
    • Silibinin 5mg/kg IV over 1 hour then infusion 20mg/kg/day for up to 3 days
    • BenPen 300mg/kg/day IV for 3 days (if silibinin is not available
    • Rifampicin 10-20mg/kg IV daily
  • Atropine if cholinergic signs and symptoms evident
  • Pyridoxine if seizure following Gyromitra mushrooms as acts like isoniazid
• Disposition
  • Asymptomatic paediatric patients can be observed at home following wild mushroom ingestion
  • Early GI illness managed supportive in ward and discharged when well
  • If symptoms >6 hours duration, check LFT and renal fx prior to discharge
  • Early consultation with hepatologist and clinical toxicologist if cyclopeptide hepatotoxins considered likely

Last Updated on October 13, 2020 by Andrew Crofton