► Mushrooms comes under food poisoning.
► These are forms of fungi which grow up from an underground mycelium, i.e. mass of filaments or hyphae constituting the vegetative portion of the fungus.
► Edible mushrooms are used as vegetables but some varieties are poisonous. Several cases of poisoning by mushrooms have been reported.
► All toxic mushrooms belong to two divisions: Basidiomycetes and Ascomycetes
● It commonly known as sac-fungi as the comycetes are mostly multicellular.
● They are saprophytic, decomposers, parasitic or coprophilous.
● Mycelium branched and septate.
● It commonly known as bracket fungi or puffballs.
● They grow in soil on logs and tree stumps and in living plant bodies as parasities eg- rusts and smuts.
● Mycelium branched and septate.
Mushroom is consists of the pileus (cap), stipe (stem or stalk), lamellae (gills), volva, veil, annulus (ring), and spores.
► The vulva is the partial remnant of the veil found around the base of the stem in some species.
► The veil is a membrane that sometimes completely or partially covers the gills.
► The annulus is a ring-like structure that may surround the stipe and is a remnant of the partial veil.
► Pileus refers to the broad, cap-like structure from the undersurface of which hang the gills.
► Spores are located on the lamellae and are microscopic reproductive. It ranges in colour from white to black, with shades of pink, brown, and purple in between.
► Stipe is the stalk or stem supporting the pileus.
Depending on the nature of toxin present, mushrooms can be classified into several groups thar are-
► Amanita species includes A. phalloides, A. virosa, A. bisporigera, A. hygroscopica, A. suballiacea, A. tenuifolia, A. verna, and A. ocreata.
► Galerina species includes G. autumnalis, G. marginata, G. sulcipes, and G. venenata.
► Lepiota species includes L. castanea, L. helveola, L. chlorophyllum, L. josserandii, L. subincarnata, and L. brunneoincarnata.
● The fatal dose of mushroom is about 2 to 3 mushrooms.
● 5 to 15 mg of amatoxins per gram of dried mushroom.
● 0.1 mg/kg of amatoxin may be a lethal dose for human adults.
● About 15 to 20 Galerina caps may kill a healthy adult.
The fatal period of mushroom is Usually 2 hours.
Mode of Action
● Phalloidin interrupts actin polymerisation and impairs cell membrane function, but has a limited absorption and therefore toxicity. Phalloidin binds to the actin F (filamentous polymer) of the plasma membranes, and hence increases the permeability of the plasma membranes of hepatocytes.
● Amatoxins are more potent. It disrupts protein synthesis by inhibiting the enzyme RNA polymerase II. When ingested, the liver is the organ usually affected first and survivors may require a liver transplant. The other organs affected are GI tract epithelium, kidneys. Cells with the highest rate of multiplication, such as the intestinal mucosa, are injured first, followed by the liver and kidneys.
● Muscimol is a psychotic alkaloid found in some species of Amanita but is less toxic than the amatoxins. It is a potent agonist of GABA receptors and causes visual perception problems and auditory hallucination.
Sign and Symptoms
Short Incubation Poisoning
It includes Omphalotus species and Coprinus groups.
- Blurred vision
- Abdominal cramps
Long Incubation Poisoning
It includes Gyromitra group and Amanita phalloides and Galerina group.
- Muscle cramps
- Severe abdominal pain
- Abdominal pain
- Diarrhoea fever
- Electrolyte imbalance
Severe liver and renal damage
- Acute renal failure with hepatic necrosis.
- Septic infection
- Encephalopathy with convulsions.
- Cardiovascular collapse
● Gastric lavage with activated charcoal.
● Emesis and catharsis are usually suggested.
● Restoration of fluid and electrolyte balance.
●Charcoal plasmaperfusion (CPP) and continuous venovenous haemofiltration (CVVH) have been effective in a few cases.
● Antidote benzyl penicillin at a dose of 300,000 to 1,000,000 units per day is said to be effective in displacing amatoxin from plasma protein-binding sites allowing for increased renal excretion.
● Endotracheal intubation if patient is comatose.
● Continuous pulse oximetry.
● Mechanical ventilation, if there is evidence of hypercapnia or hypoxia.
● Prevention of hypoglycaemia by continuous infusion of 5 or 10% dextrose.
● If hypoglycaemia develops, infuse 50% dextrose.
● Treatment of hypotension with crystalloid or colloid solutions, or drugs such as dopamine, noradrenaline, etc.
●Treatment of renal failure with dialysis or arterio -venous ultrafiltration.
●Prevention of gastroduodenal bleeding with regular doses of H2 antagonists or omeprazole.
● Osmotic diuretics such as mannitol have been suggested.
● Barbiturates such as IV thiopentone (3 to 5 mg/ kg) have been administered.
● Plasma exchange is also useful.
● Stomach washes with potassium permanganate.
● Atropine sulphate.
● Antiphalloidien serum.
●Thioctic acid is obsolete.
● Inflammation of the mucous membrane of the alimentary canal, fatty degeneration of the liver, kidneys and heart may be seen.
● In case of neurotic symptoms, congestion of the brain and petechial haemorrhages in serous membranes are also seen.
Medico legal Aspects
● Most cases of mushrooms poisoning are caused by people collecting wild mushrooms and mistaking poisonous mushrooms for edible species.
● Occasionally, they are involved in homicides.
● Poisonous mushrooms are rarely used for suicidal purposes but have been reported.
Forensic examination and Test for Detection
► Physical Test
● Spores may be fairly uniform in size and shaped somewhat like an apple seed or popcorn kernel.
● They are about the size of a red blood cell (approximately 7 microns).
● Amanita spores are hyaline, thin-walled, and without a pore.
● Spores of less toxic species are thickwalled with a pore.
● Dark-coloured spores indicate a genus other than Amanita.
► Meixner Test
This test can be done on either stool or gastric sample. Dilute the sample with methanol, centrifuge, and filter it. Add a drop or two to a piece of newspaper. Encircle the spot with a pencil and dry it. Add a few drops of concentrated hydrochloric acid to the spot. If a blue colour forms within a few minutes, it is indicative of the presence of amatoxin which is present in most of the mushrooms.
► Melzer’s Test
This is a test done to confirm whether a given mushroom is toxic (especially Amanita phalloides). The spores obtained from the mushroom are stained with 1 drop of Melzer’s reagent (mixture of 20 ml water, 1.5 gm potassium iodide, 0.5 gm iodine, and 20 gm chloral hydrate), and viewed under a microscope. Spores of A. phalloides and a few other deadly mushrooms will show a bluish black colour (“amyloid reaction”). However, a negative reaction does not mean that the mushroom is non-toxic.
► Hepatic and renal function tests.
► Detection of toxins in gastric aspirate, serum, urine, stool, and liver and kidney biopsies using
► Instruments such as-
► High Performance Liquid Chromatography
► Thin Layer Chromatography
► Radio Immuno Assay
Dr. K.S. Narayan Reddy. The essential of forensic medicine and toxicology.34th edition.
VV Pillay. Modern medical toxicology 4th edition.
R.K.Sharma. Concise textbook of forensic medicine and toxicology. 3rd edition.