Tox Cards: Mushrooms

Author: Kristin E. Fontes, MD (Emergency Physician, Santa Barbara Cottage Hospital and Goleta Valley Cottage Hospital) // Edited by: Cynthia Santos, MD (Senior Medical Toxicology Fellow, Emory University School of Medicine), Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UT Southwestern Medical Center / Parkland Memorial Hospital), and Brit Long, MD (@long_brit, EM Attending Physician, San Antonio Military Medical Center)

Case presentation:

A 42-year-old previously healthy woman presents to the emergency department with malaise and anuria. She states she became ill with abdominal pain and vomiting from “food poisoning” 3 days ago, and thought she might be dehydrated. Her previous symptoms have resolved and, despite increasing oral fluid intake, has not had any urine output in the last 24 hours. On further questioning, she tells you that she just returned from a trip to Oregon where she foraged for wild mushrooms. Vital signs are within normal limits. Laboratory evaluation reveals acute renal failure.

Questions:

• What is the typical acute presentation of mushroom poisoning?
• How long after exposure do symptoms develop?
• What are the potentially life-threatening complications?
• Is there an antidote?

Pearls:

• About 1-2% of wild mushroom varieties are toxic
• “Little brown mushrooms” are usually associated with benign toxicity (immediate symptoms), but mushroom identification should only be done by a mycologist
• Think of mushroom poisoning in terms of time to initial symptoms after ingestion:
  • Immediate symptoms (i.e. within 6 hours) usually indicate a benign poisoning
  • Delayed symptoms (i.e. more than 6 hours) indicate a potentially life-threatening poisoning
• Most common immediate symptoms are gastrointestinal (GI): abdominal pain, vomiting, and diarrhea (usually self-limited)
• Potentially life-threatening mushrooms may also present initially with gastroenteritis:

• Other poisoning syndromes (rarely life-threatening):

• Mechanisms of toxicity:
  • Amatoxins – destruction of organs with high protein synthesis rates such as liver, GI tract, and kidney
  • Non-amatoxins – most commonly direct irritation of GI tract mucosa; CNS depression may be due to GABA-like effects (muscimol), whereas excitation may be explained by activation of glutamic acid receptors (ibotenic acid) or by post-ganglionic cholinergic effects (muscarine)
• Treatment
  • GI decontamination – activated charcoal if clinically appropriate
  • Aggressive supportive care effective for most
  • No FDA-approved antidotes currently
    • Consider pyridoxine for seizures, methylene blue for methemoglobinemia due to monomethylhydrazine ( esculenta) poisoning
    • N-acetylcysteine may be effective for hepatotoxicity
    • Silibinin, an extract of milk thistle, is a potential antidote for amatoxin poisoning that may act by preventing amatoxin uptake into hepatocytes; U.S. clinical trial currently underway

Main point:

• Delayed toxicity after mushroom ingestion is potentially life-threatening; provide aggressive supportive care and consider antidote therapy when appropriate

References:

1. Olson KR & California Poison Control System. (2012). Poisoning & drug overdose. New York: Lange Medical Books/McGraw-Hill.
2. West P. Amanita smithiana mushroom poisoning. In: UpToDate, Traub SJ (Ed), UpToDate, Waltham, MA. (Accessed on May 27, 2017.)
3. Limoges DR, Burda AM, Gil M, Rothman JJ. Silibinin for cyclopeptide mushroom poisonings. Am J Health Syst Pharm 2012 Nov 1;69(21):1856.
4. West PL, Lindgren J, Horowitz BZ. Amanita smithiana mushroom ingestion: a case of delayed renal failure and literature review. J Med Toxicol 2009 Mar;5(1):32-8.