Destroying Angel

Destroying Angels are a group of species of the genus Amanita, which also includes the European A. phalloides (death cap) and North American A. muscaria (fly agaric). A. bisporiga is found across the East coast of the USA, while A. ocreata is its counterpart in the West. Both species are a pale-to-white color and are often mistaken for edible button mushrooms by inexperienced foragers.

Like many other Amanita species, destroying angels contain amatoxins. These are heat-stable bicylic peptides which potently inhibit RNA polymerase II, leading to arrest of gene transcription followed by cell death. The lethal dose of 0.1 mg/kg can be easily surpassed with the ingestion of a single small mushroom.

Presentation:

The symptomatology of amatoxin poisoning is typically divided into several phases. The first (or zeroth) phase, the "incubation" phase, is asymptomatic and lasts for 6 to 12 hours.

The next phase, between 12 and 24 hours, is the "gastrointestinal" phase and is characterized by abdominal pain, vomiting, and copious watery diarrhea, possibly leading to severe dehydration.

The third "hepatotoxic" phase, between 24 and 48 hours, features signs of liver necrosis — hyperbilirubinemia, coagulopathy, hypoglycemia, etc.

In the last phase, patients progress to acute liver failure and kidney failure. Encephalopathy, cerebral edema, and cardiac arrest all contribute to the mechanism of death.

Management:

If amatoxin poisoning is suspected, either from the history or from the symptomatology (such as delayed elevations in liver function enzymes), LFTs should be trended to evaluate degree of hepatotoxicity. Silibinin, a flavonolignans extracted from milk thistle, has been demonstrated to have a small mortality benefit; benzylpenicillin (Penicillin G), ceftazidime, and thioctic acid have also been used with less clinical evidence.

GI decontamination is controversial as patients generally present during the gastrointestinal phase, many hours after ingestion. As amatoxins enter the enterohepatic circulation, it has been suggested that pulsed-dose activated charcoal may reduce their concentration.

Supportive care is the other mainstay of treatment — correction of electrolyte imbalances, aggressive fluid resuscitation and maintenance of urine output, protein restriction, repletion of coagulation factors, lactulose and neomycin to prevent hepatic encephalopathy, and mannitol to reduce intracerebral pressure. As amatoxins are readily eliminated in urine, preserving urine output also serves to reduce potential toxicity. Hemodialysis and hemoperfusion, while not actually effective at reducing amatoxin levels, may be indicated if symptoms of hepatic and renal failure worsen.

If liver failure continues to progress, total or partial liver transplant are definitive treatments. Ideally, the decision to transplant should be made while the patient is still considered "sufficiently stable" for surgery.