Plant Toxicity and Mushroom Poisoning

Plant Toxicity

• A poisonous plant is one that, in sufficient amounts, causes harm or death to an organism.
• Examples include mushrooms, foxglove, castor beans, and tobacco.

Mushroom Poisoning

• Mushrooms are the fruiting bodies of fungi.
• Toxicity occurs after ingestion of mushrooms containing toxins.
• Many mushroom species look similar but have vastly different toxicities.
• Approximately 100 species of mushrooms can cause symptoms in humans.
• Only 15-20 species are considered potentially lethal when ingested.
• There's no simple way to distinguish safe from poisonous mushrooms.

Pathophysiology

• Each poisonous mushroom contains one or more toxins.
• Mushroom poisoning severity depends on the mushroom species, location where grown, amount of toxin, and recipient's genetics.
• Cooking, freezing, boiling, or processing does not always eliminate toxicity.
• Poisoning is categorized by the time from ingestion to symptom onset:
  • Early: first 6 hours. (gastrointestinal, allergic, or neurological)
  • Late: between 6-24 hours. (hepatotoxic, nephrotoxic)
  • Delayed: more than 24 hours. (mostly nephrotoxic syndromes)

Mushroom Toxins

• Several toxins exist, including:
  • Amatoxins (Cyclopeptides): powerful toxins. 0.1 mg/kg can be lethal. A single mature specimen of Amanita phalloides (death cap) can contain 5-8 mg of amatoxin and is potentially lethal. They are cyclic octapeptides synthesized by Amanita species. Amatoxins are rapidly absorbed from the gastrointestinal tract. They can be detected in urine as early as 90-120 minutes after ingestion. The major toxic action of amatoxins is inhibition of RNA polymerase II, leading to protein synthesis blockage.
  • Gyromitrins (monomethylhydrazine): inhibit numerous hepatic systems (including cytochrome P450 and glutathione). Cause hepatic necrosis. Inhibit pyridoxine kinase which is involved in GABA production, leading to CNS hyperexcitability and seizures.
  • Orellanine: primarily affects the renal tubules, causing necrosis with relative sparing of the glomeruli.
  • Muscimol and ibotenic acid: related to GABA (gamma-aminobutyric acid), acting as GABA receptor agonists. The similar structure allows for mimicking GABA and acting on GABA receptor sites in the nervous system.
  • Norleucine: nephrotoxic.
  • Muscarine: stimulates M1 & M2 muscarinic receptors. Produces cholinergic symptoms like sweating, facial flushing, salivation, lacrimation, vomiting, abdominal cramps, diarrhea, urination, and miosis.

Complications

• Respiratory: Aspiration pneumonia is a possible complication.
• Neurologic: Convulsions, cerebral edema, hypoxia, acidosis, or trauma.
• Hepatic: Failure and hypoglycemia.
• Renal: Failure, hypoperfusion, and shock.
• Hematologic: Methemoglobinemia, hemolysis,
• Other: Trauma, hypovolemia, electrolyte imbalances.

Treatment

• Early volume resuscitation (fluid rehydration) crucial for liver and renal problems.
• Gut decontamination: Whole bowel irrigation.
• Multiple doses of activated charcoal: Interrupts enterohepatic circulation.
• Endotracheal intubation: Risk of aspiration, needed for hypoxia, acidemia, and shock, mechanical ventilation.
• Agitation: Benzodiazepines.
• Severe muscarinic symptoms: Atropine.
• Disulfiram-containing mushrooms: Fomepizole (blocks alcohol dehydrogenase).
• Severe renal failure: Hemodialysis.
• Severe hyperkalemia or fluid overload: Dialysis
• Blood transfusions: for severe hemolytic anemia, hemorrhagic diarrhea, and blood loss.
• Blood pressure support: Dopamine and norepinephrine if crystalloid and colloid infusions fail
• Hypoglycemia: 10% dextrose infusions.

Explore the dangers of poisonous plants and mushrooms in this quiz. Learn about the specific toxins present in various mushrooms and the potential effects of ingestion. Understand the factors influencing mushroom toxicity and why cooking does not always eliminate danger.