Poisoning by Amanita phalloides ("deathcap") mushrooms in the Australian Capital Territory

The dose ranged from a quarter to eight mushrooms. All patients presented after one to two days with diarrhoea and, in most cases, vomiting, except the child, who vomited within two hours and was brought for medical attention immediately. The diagnosis was made on initial presentation in only this child and the other 1998 patient (Patient 2).

Three patients developed significant hepatic dysfunction, and two were transferred to a liver transplant unit, one of whom died. Details of the two who were transferred follow.

Initial investigations revealed the following serum levels: alanine aminotransferase (ALT) > 10 000 U/L (reference range [RR], 5-55 U/L); bilirubin, 114 µmol/L (RR, 3-20 µmol/L); creatinine, 535 µmol/L (RR, 40-90 µmol/L); and prothrombin time - international normalised ratio (PT-INR) > 10. A mycologist identified A. phalloides growing in the street where the patient had picked the mushrooms and also identified the mushroom stalks that he had discarded in a rubbish bin.

The patient was transferred to a liver transplant unit but died from hepatic failure six days after mushroom ingestion. Postmortem examination of his liver revealed complete necrosis of parenchyma, with one residual island of intensely vacuolated hepatocytes with severe intracanalicular biliary stasis. No viable hepatocytes were seen.

Initial investigations revealed the following serum levels: ALT, 914 U/L; bilirubin, 24 µmol/L; and creatinine, 102 µmol/L. He had evidence of metabolic acidosis, with pH of 7.30 (RR, 7.34-7.44) and bicarbonate level of 18.6 mmol/L (RR, 22-26 mmol/L). The mushrooms were identified as A. phalloides by a mycologist.

The patient was transferred to a liver transplant unit and treated with intravenous fluids, high dose penicillin and N-acetylcysteine. Three days after mushroom ingestion, his serum ALT level peaked at 8199 U/L, and PT-INR at 4.7, but he did not develop encephalopathy. He subsequently made an uneventful recovery.

A. phalloides is a mycorrhizal fungus (ie, it grows in a symbiotic association with the roots of trees, primarily oak trees). It produces a range of toxins (amatoxins). The major toxin, a cyclic peptide, amanitin, inhibits RNA polymerase II and is not inactivated by cooking, freezing or drying. The lethal dose is about 0.1 mg/kg, which may be contained in as little as one mushroom.⁵ Amanitin is usually cleared rapidly, mainly by renal excretion.⁶

Recommended treatment of A. phalloides poisoning includes vigorous gastrointestinal decontamination.⁷ Early and aggressive decontamination may have prevented toxicity in the seven-year-old child. Supportive care, including intravenous rehydration, is thought responsible for most of the improvement in mortality, from well over 50% early this century to 20%-30% in recent decades.¹ Many specific antidotes have been used, although no prospective-trial evidence is available. Retrospective clinical studies and animal studies support the use of high dose penicillin (0.5-1 million units/kg per day) and parenteral silibinin, an extract of milk thistle available only in Europe. Both are thought to act by inhibiting amatoxin uptake into hepatocytes and by interfering with its enterohepatic circulation.^1,7 Cimetidine, a hepatic enzyme inhibitor, may be harmful.⁸ We speculate that, in Patient 1, long-term use of griseofulvin (a hepatic enzyme inducer) before poisoning may have increased the rate of detoxification of amatoxin and thereby contributed to survival. Liver transplantation may be used in cases that fail to respond to more conservative measures. It has been performed successfully for this indication in the United States since 1985,⁹ but has not been attempted for this indication in Australia.

A. phalloides mushrooms have been described in many regions of south-eastern Australia. Collections have been made in several Melbourne suburbs,^4,10,11 and the Victorian country centres of Riddells Creek, Morwell and Walhalla.¹¹ The National Herbarium of Victoria and the State Herbarium in Adelaide hold collections of A. phalloides or very similar species from New South Wales, Tasmania and Victoria. A. phalloides mushrooms were first reported in Canberra in 1961⁴ and are now widespread in the ACT.

Although A. phalloides is found primarily in association with oak trees, there is concern among mycologists and toxicologists that it may develop the ability to grow in association with other trees, particularly Australian natives, and thereby spread dramatically. Associations between Eucalyptus spp. and Amanita spp. other than A. phalloides have been reported in other countries,¹² and between Eucalyptus spp. and A. phalloides itself in Africa.^13,14 There is anecdotal evidence of A. phalloides forming mycorrhizae with Eucalyptus spp. in Canberra (Richard Windsor, consultant botanist, Canberra, ACT, personal communication).

A. phalloides is not the only mushroom to contain amatoxins. In the northern hemisphere, these toxins are found in other Amanita species and in species within the genera Conocybe, Galerina and Lepiota,¹ which also occur in Australia. Four cases of Lepiota helviola poisoning have been reported from Adelaide. In each, hepatotoxicity occurred and amatoxins were identified.^4,15

A. phalloides is now widely distributed in south-eastern Australia, and may become more widespread if it develops the ability to grow in association with eucalyptus trees. Increased community and clinician awareness is needed to reduce the incidence of poisoning and to improve outcomes. Wild mushrooms should not be eaten unless definitely identified as non-poisonous. Clinicians should consider A. phalloides poisoning in patients with vomiting, diarrhoea or abnormal liver function.

1. Benjamin DR. Amatoxin syndrome. Mushrooms: poisons and panaceas -- a handbook for naturalists, mycologists and physicians. New York: W H Freeman and Company, 1995: 198-241.
2. Pond SM, Olson KR, Woo OF, et al. Amatoxin poisoning in northern California, 1982-1983. West J Med 1986; 145: 204-209.
3. Nicholson FB, Korman MG. Death from Amanita poisoning. Aust N Z J Med 1997; 27: 448-449.
4. Southcott RV. Notes on some poisonings and other clinical effects following ingestion of Australian fungi. S Aust Clin 1974; 6: 442-478.
5. Weiland T. Poisonous principles of mushrooms of the genus Amanita. Science 1968; 159: 946-952.
6. Jaeger A, Jehl F, Flesch F, et al. Kinetics of amatoxins in human poisoning: therapeutic implications. J Toxicol Clin Toxicol 1993; 31: 63-80.
7. Floersheim GL. Treatment of human amatoxin mushroom poisoning: myths and advances in therapy. Med Toxicol 1987; 2: 1-9.
8. Schneider SM, Vanscoy G, Michelson EA. Failure of cimetidine to affect phalloidin toxicity. Vet Hum Toxicol 1991; 33: 17-18.
9. Klein AS, Hart J, Brems JJ, et al. Amanita poisoning: treatment and the role of liver transplantation. Am J Med 1989; 86: 187-193.
10. Reid DA. A monograph of the Australian species of Amanita Pers. ex Hook (Fungi). Aust J Bot Supplementary Series No. 8, 1980: 48.
11. Cole FM. Amanita phalloides in Victoria. Med J Aust 1993; 158: 849-850.
12. May TW, Wood AE. Extra-Australian species associated with Eucalyptus. Fungi of Australia. Volume 2A. Canberra: Australian Biological Resources Study and CSIRO, CSIRO, 1997: 239-240.
13. Malencon G, Bertault R. Flore des champignons supérieurs du Maroc. Tome I. Rabat, Morocco: Faculté des Sciences, 1970: 75.
14. Pegler DN. Amanitaceae. A preliminary agaric flora of East Africa. London: HMSO, 1977: 296-297.
15. Lloyd C, White J, Downes S, et al. Amatoxin poisoning following ingestion of Lepiota helviola. Report of two cases with hepatotoxicity. Abstracts of the 10th World Congress on Animal, Plant and Microbial Toxins. Singapore; 1991 3-8 Nov. 1991: 345.

Australian National Herbarium, Centre for Plant Biodiversity Research, Canberra, ACT.
Heino Lepp, BSc(Hons), Scientific Associate.

Royal Prince Alfred Hospital, Sydney, NSW.
Matthew J Hall, MB BS, Gastroenterology Registrar;
Geoffrey W McCaughan, FRACP, PhD, Physician-in-Charge, Australian National Liver Transplant Unit;
Geoffrey G Duggin, FRACP, Head, Toxicology Unit.

Reprints will not be available from the authors.
Correspondence: Associate Professor D G Le Couteur, Department of Clinical Pharmacology, The Canberra Hospital, Yamba Drive, Garran, ACT 2605.
Email: david_lecouteurATdpa.act.gov.au