FOOD SPOILAGE BY FUNGI- 3{)1

Kceping in mind the kind of techniques we have developed for preventing or retarding mould spoilage of foods, we can now make aquick survcy of the main groups of foods, ami the kinds of moulds that cause spoilage problems in each. Foods from plants fal l into four broad categories: (I) cerenls and UUIS. (2) sugars. (3) vegetables, (4) froits. Those of anim31 origin provide a further fou r categories; (5) meat and pouluy. (6) eggs. (7) fi sh and other seafood, (8) milk and milk products, We wil! e:tamine them in that order.

(I) Cereals and nuts. If promptly harvested and stored under dry eonditions, mosl of these naturally dry f()Od.o; are relath'ely immune to fungal spoilage. But if the growing season is wet. grain can become mouldy while still in the field. Some field moulds are notorious rnycotoJ\in producers-Fusarium spp.* produce zearalenone. T-2 toxin and "omitoxin. Some storage moulds !hat attack grnin and nuts are equally infamous-JI.s-

and A. parasiriclls* produce anatoxin . Rice. which is grown in wann, wet conditions, is often moulded by species of AspergillI/!; or Penicillil!m; and rice sta ined yellow by P. cirrinum*, P. isla!lllicum and P. often contains mycotoxins. Barley isollen contaminated with ochratoxin produced by P. var. Corn can be spoiled by Fusa rium gramineam m or Aspergll/lu flavus. which produce zearalenone and aflatoxins. respectively. Corn and winter wheat in the field are threat-ened by FusurilUn graminl'anml, the source ofvomitaxin. and wheat in storage is some-times spoi led by members of the Aspergilllls glallCIIS by A. candidus, A .fl{lVlU*. A. ochmuus". and by some penicillia,

If flour is stored at a moisture content of 13% or Jess . it won' t mould, but the addition of water du ring baking makes the finished product available to fungi. The cont-moneM moulds on bread are: the zygomycete. Rhizopus stolonifu. with ilS tall sporangio-phores and black pinhead sporangia; the green-spored hyphomycetes, Penicillium I'xpa/lSwn* and P. slQ/onijemm; the blacksporcd Aspergillus and Ihtl pinkish ChryIonifia silQphiia anamorph of Neurospora. Species of the zygomycete genus Mucor ;md the filamentous yeast Georrfchum may also be involved. Wheat bread is often moul-ded by Penicilliwn b revictJmpacwm*. P. ChT)'stJgemml and P. \'crrucuswn var. cye/opium; rye bread by the last species and P. roque/onii"; pastrics by Aspergillus repem and P. \'ermcosum VaT. eye/opium*.

(2) Prope rly mad. Penicillium cOT)'lup;'ilum and Wallemia $Cbi, and means that jam m3kers h3ve h3d to resort to such supplcment3ry me3sures as slrile filling of comainers, refrigeration. and even chemical preservati ves.

(3) Vegetables. Some vegetables. such as cabbages. potatoes and turnips, are rela tively resistant to fungal spoibge. Others, such as lenucc and ripe tOmatoes. ba"e a much shoner shelf-li fc. The mo,! serious fung31 market dbeascs of vegetables arc grey mould rot caused by Borrytis (Hypbomycetes). w.3lery soft fO!. caused by tbe sclerotial anamorph of Sclerolinia (AscomYC

30! CHAPTER TWENTY

n common problem on ripe peaches. Tropical fruits are often auacked by species of COIII'IOlrichnm* (Coclomycetes).

Fruits are often preserved by drying or canning (or by m.1king into jam. as men tioned under heading 2), and frui t juices now support a whole industry. Apricots and peaches for drying arc impregnated with sulphur dioxide to preser.'e their colour. and this also effectively preventS fungal spoilage. Unsulphured dried fruit can go mouldy. Prunes, especially. afe sold in moist path which have an a.. of 0.SO-O.S5. This makes them accessible to most xerotoierant moulds, which can be inhibited by sorbic or benzoic acid. Canned goods are usually heated to a high enough temperature to destroy fungal spores. but fruits with delicate texllires are pasteurized at lower temperatures. Healing 10 SOQC will kill al1 zygomycete sporangiospores, and all hyphomycete conidia; but it won't kill ascospores of BJ$$och{{ImJsfi,hu or B, lIivea. These Ihennotolerant ascomycetes some-times spoil canned strawberries, soft drinks and fruit juices (prune, grape. pineapple). and home-bottled fruit. If these fungi are cultured. their Pal'dlomJces aml.morphs usually develop. Fruit juices arc naturally contaminated with yeasts.. and the !lonna! course of events would in\olve an alcoholic fermentation which would ultimately. as in the case of wine, effec tively preserve the substrate, But if the juice is refrigerated. moulds. rather than yeasts, will be favoured. Some fruitjuices(blad:curram, grape) are preserved with sulphur dioxide. In conclusion, it is .... orth pointing out that we can't blame all f("\lit losses on the fungi-bananas become brown and mushy through the action of their own enzymes.

(S and 6) Meal and Eggs. Although mOSl serious spoilage of foods of animal origin is caused by bacteria. species of Penicillium* and Aspergillus . are commonly recorded. aod may produce mycOioxins such as cyclopiazonic acid. penitrem A, ochratoxin. jXltulin and anatoxin. Fungi can ~ inhibited by refrigeration. vacuum packing. drying or irradia-tion.

(7) Fish , usually dried. is most frequently contaminated by Eurol illm'", Seopulariopsi.r. and Penicillium- species. /I.lyeotoxins produced arc OI.:hratoxin A and cit reoviridin. Reducing the water activity of the substrate is the best way of preventins fungal spoilage.

(8) Raw l\lilk is u.'ually spoiled by bacteria ~fore fungi can begin to affec t it. Pasteurization and airtight. refrigerated storage are the ~st ways to prolonS its shelf life. Conversion to dried milk or cheese will also extend its life. but cheese is commonly attacked by fungi. especially P~l!icillilrm comllwne *. but also b>' other penicillia . A.r persillus ve~icolor. Sc{lp/l/ariopsis spcdes and /lrolium herbariom",. Spoilage is delayed by reducing water activity, by vacuum packing. and by refrigeration.

Further Reading Frazier. W.C and D.C Westhoff( 1975) Food MicrobioloJ,;Y. 3ed &In. McGraw-Hili, New

York-

Pitt . J .I. (19SI) Food spoi\ag~ and biodct~rioration (in) Biology or Conidial Fungi. Vol 2. (Eds.) G.T. Cole and B. Kendrick. Academic Press, New York.

Samson. R.A. and E.S. van Reenen-Hoekstl"il (19S8) Ln troduction 10 Food_horne Fungi. 3rd Edn. Centraalbureau voce Schimmelcultllres, Banrn (with contributions by 12 other authOr

~ UFPECCB /DBIBLIOTECA

Mycotoxins in Food and Feed

Introduction

21 Foods are usually noll-living bur natural organic substances, wllich are excellent

~ubs[ra[es for sapIc bic fungi. and accordingly Icnd to go mouldy if kepi too long. The people of western countries. ge neral ly rel:uive ly wealthy and faslidious, will throw Qut most food that is obviously mouldy. BUI this is not necessarily true in the poorer nations, where food is often a precious commodity. not [0 be rejected because of a little Slilface di scolouration. This ultitude is re inforced in the Far Easl by the !;ommon use of moulds to prepare traditionul fermented foods (see ch:lptc r 19). In some areas, indigenous peoples prefer the spicy na\'our certain foods acquire when they go mouldy (d. the blue cheese eate n by westerners). Animal,; will ohen accept mouldy feed. To compound tbe problem. the teon mouldy refers only to food on wbich the contaminating fungi are already sporo-lating. BUI even food whieh looks perfectly edible may be riddled by lhe invisible assimi-lat ive hyphae of moulds. and contaminated by their metabolites. Do these tbings mailer? [s mouldy food d3nerous? This chapter will gh'e yOll some answers.

Some fungi. including many common moulds (mostly hyphomycctes). produce secondary me ta bolites-usually st~rojds, c~rolenoids, alkaloids. cyCIOpcpl idcs and coumarin, . Many substances in the IJstthree categories are tQxil: 10 animals and to other mil:roorganisms at very low dosages. and are also pe[1;istenl and often lIeat-stable. Sueb compounds are frequently produced in fungus-contaminated foodstuffs. remain there even afte r processing. steri lization or cooking. and are unsuspectingly eaten. They are called mycolo.~ ins. Over 100 stleh substanceS. produced by about 150 diffe rent fungi. are now known, and more are being discovered every year.

Ergot Alkaloids and Saini Anlhony's Fire We have become aware of most mycotoxiM and their insidious effects only since

1960, but Ihe condition called ergntism has been known for tOOus:lnds of years. This mysterious and dre3dful disease stroo:k the 5p.1I1ans in 430 Be during their """aT with Athens. Epidemics during the ~'1iddle .-\ges h:tvc left bizarre ao:rounlS in whicb the sereams of the dying. the stencil of rotting flesh. :tnd limbs aC1U~lly dropping off arc: Te

3G4 CllAPTER TWENTY-O:\"E

We now know that the vi~tims had all caten bread madc from grain com3.minated with sclerotia of the ergOI fungus, Cla vicep$ purpure(l (Fig. 4. 18 AD). The$(' sclerotia contain a comple:l. cocktail of physiologically ac tive substances: ten differeD! groups with ovcr 100 individual compounds. The disease-producing substanccs are alk.1loids of two main kinds: (Il cJavinc alkalo ids; (2) derivatives of lysergic add-amides or po!p-tides.

Wh:1I was the disease like'! Two main patterns were seen. (I) Gangrtflous crxotisrn. This syndrome began " 'ilh fatigue. and cold or prickling sellsatioos in the limb . then se,-ere muscular pains. Limbs later became swollen and inflamed. and burning pains and sensations of heat alternated wi th those of icy coldness. Gradually the affeCt

MYCOTOXIi\"S IN FOOD AND FEED 305

So. on the one hand. ergot is now produced dcliberatdy by the pharmaceutical industry, spores of the fungus being mechanically inoculated into the flowers (If rye: on the other hand, ergot is ll(lW rigmously excluded from grain that will be gruund for flour. No longer do we necd w take pi lgrimages to 51. Anthony's shrine to give ourselves a br~ak

from an ergot- cont~minated diet (Yes. that seems to have been the secret of those miracu lous cures). Only animals and the occasional alkaloid-overdose patient now suffer from St. Anthuny's Fire. A few years ag(l in England. ergOlamine tartrate was prescribed fo r a woman suffering from migraine. Unhappily, the amount prescribed was a massive over dose, she developed gangrene in her feet. and her loes had to be amputated. In Canada a hog farmer lost most (If his pigs to ergot pois(lning. He was awarded $100,000 damag~s against the feed supplier, despite the fact that the grain had not exceeded the level of ergot contamination permilted by the Canadian Grain Commission. C/aviceps purp"ren has not lost its ancient powers, and its to.'l..ic effects can be avoided only by constant vigi -lance.

Aflatoxins- Toxins, Mutagens, Carcinogens The modern awakening of scienti,ts to an awareness of mycotm;: ins began in 1960,

when tens of thousands of turkey poults in England begun to die from a myst

306 CJL\PTER TWENTY-ONE

rabbit~.3, ':11.-0.55, pigs----O.62, shee~I.O. Th31"5 bad enough, but it was dis,o\'-ered that even if the diet didn't contain sufficient loxin to ,ause a,ule poisoning, pro-longed exposure 10 IDu,h lower levels will often cause liver cancer. Many experiments have demonsu;"l1ed this in rats. As little as O.Q1S ppm (parts per million) in the diet over 70 weeks caused neoplasms in all rats tested. At I ppm this takes only 40 weeks. At 5 ppm it takes 9 weeks. Sh.asta trout are so sensitive thai as little as 0.5 Ilg/kg (0.5 ppb) in their food over 20 months will produce similar results.

If we examine the incidence of liver cancer in human populations, we find it is exceptionally common in some developing countries, especially those of Subsaharan Africa and the Far East. The problem i ~ well documented in Uganda. Swaziland, Kenya and Thailand. All have elevated levels of liver ,aneer, and the diet in ea,h country is significantly tontaminated with aflatOxins. Although we cannot, of course. prove experi-ment:llly th3t aflatoxins cause liver cancer in humans, the suspicion is strong enough to be almost a ,erlainty (as with the connect ion between smoking and lung cancer). And we do know Ihat in some other mammals, aflatoxins are the most potent carcinogens yel discovered.

fig. 21.1 The pl"ndpJl genera of to-cigeric anamorphs.

G. CWJo'porium h."O;>

l\ IYCOTOXL~S IN .'000 A!'o'D FEED 307

What is being done to monitor and conlmi the levels of aflatoxins in our diet? In Canada the allowable limit of contamination, originally 20 ppb in a finished prodUCt, has been reduced 10 15 ppb. Germany allows only 10 ppb. I believe that no detectable afla-toAin should be permilted. Ifproper auention was paid to storage and selection of peanuts for human consumption, and to appropriate dilution of mildly contaminated nuts, this standard OOIIld be easily attained.

Aspugillus flavus competes beSt in wann climates, on substrates that have low water Contems (low 'water activities': see chapter 20). It was originally classified as a storage mould. but some rontaminarion has now been traced back to the field: the fungus can be an adventitious parasite. invading insect-damaged tissue. Serious aflatoxin con-taminat ion has been found in peanuts. brazil nuts. pistachio nuts. almonds. walnuts. pecans, filberts, cottonseed, copra. com. grain sorghum. millet. palm kernels, beans. wine, milk. cheese, dried fish , garlic, spaghetti , noodles, bread, flour, and figs . Aflatoxicosis is mainly encountered in wanner climates, and it is in teresting to note that peanutS now grown in Ontario seem to be free of nflatoxin--one advantage to living so far nonh.

Mycotoxins and Oesophageal Cancer In at least two areas of the world. the incidence of oe~ophageal cancer is many times

higher than might be expected. The reasons for th is have only recently begun 10 be understood. In Lin Xian, China. not many years ago, oesophageal cancer kiHcd 25% of the population. and the disease had tmgically become an accepted part of existence. Folk wisdom held thaI if you had trouble in swallowing it was because you were unhappy. Scientists. howe"er, suspected that nitrOsamincs were responsible.

The foods people ate did no! ~onlain elevated levels of nitrosamines. but it was established that these compounds could easi ly be produced in the stomach fro'n nitrites and amincs. Grndually. the pieces of the puule were fined together. Although the local water was not initially vcry high in nitrite. people simmered their com for hours. concen-trating the nitrite. and then used the water to make soups. The soil was low in molybde-num, a deficiency which caused crop plants to aceunmlate nitrite in their Jea,es. So body levds of nitrite were foulld to be high. whi le vitamin C intake was low. Apparently, without adequate vitamin C, the body OOIIld 1I0t rid itself of the nitrites. The peasants made steamed bread from the com. NOthing unusual in that, except that Ihey m~de enough at one time to last for three: weeks. Needless to say, the bread St:lrted to go mouldy after a few days. But this didn' t bother the people of Lin Xian: they liked the spicy flavour of the mouldy bread (remember my comments on cultural detennination of what consti tutes food spoilage?) Scientists found tbat two of the fungi involved in the moulding cau~d levels of amines in the bread to increase seventeen-raid. Here was another piece of the puzzle. Rats fed nitrites and mouldy IH"ead manufactured nitrosamines, and de"eloped cancer. But it was also noted that some of tlte control r~ts. those fed only mouldy bread. 3lso developed cancer. Some of the fungi mu,l produce unknown carcinogens. Doctors also found that 90% of the concers surgically removed from patients actually had these moulds growing inside them. This was Jnother irnport3nt observation, because many apparently healthy prople already had pre-cancerous thickenings of their oesophagus, 72% of which harboured living moulds.

~ etiology of the disease was now much cle3rer. Molybdenum-deficient soil led to nitrite accumulation in crops; vitamin C deficiencies permitted high body nitrite lev-els. Mouldy bread was high in amines and harboured fungi that produced carcinogens. Now it was time to institute preventive measures. Seeds 3re being !reated with molybde-nu m. People are supplied with piped water free of nitrite. People are told to eat fresh \-egetables, and toavoid mouldy food 3t all co.~ts. Unfottun3tely. it takes ye3rs for aeancer

308 C HAPTER T WEt'lTY-Ol'\'E

10 develop, and it will be ten years before th~ results of the cancer prevention campaign can be assessed. But this is cenainly one disease where prevention. if possible. is a thou-sand times better than the attempt to cure. which involves drastic surgery and follow-up radiation treatmems, and does not have a good prognosis,

A similarly high incidence of oesophageal cancer among the Xhosa people in some pans of the Transkei, Sooth Africa, has also been connected with the wnsumption of mould metabolites in food (mainly corn) and in the native beer. whi

MYCOTOXINS IN FOOD Al'lD FEED 309

bloodcloning mechanism. Death eoold occur in less than a day. or up to a month after the onset of symptoms. Scientists eventually connected the disease to fodder contaminated with macnxyclic trichothecenes produ~ed by Swchybotrys chanarum (ct. Fig. 21. L Fl, a common cellulose-decomposing hyphomycetc growing on hay used as food and hed-ding. No fewer than n\'c stable and persistent tricbothecenc.s are produced by this fungus: \'errucarin J . roridin E, and satrntoxins F, G and H. tbough only satratoxins have been demonstra(~d in naturally contaminated straw associ~ted with an outbreak ,lmOnS sheep in Hungary. Although typically reponed in horse~. this toxicosis can also affect caule_ pigs. poultry. sheep. and even humans. Nikita Krushchcv. who later became the Russian head of state, owed some of his early career success to his recognition that horses, so "ilal to the RU'isian economy and the Red Anny transpon system of the day, needed clean. dry fodder.

Equine Leucoencephalomalacia: ' Hole in the Head' Disease of Horses

In horses. donkeys ami mules. the first signs of this condition arc apathy, protruding lOngue. unwillingness to nl O\'~ backward, and walking in circles. Evenrually the animal

':r"fP ~ ./.r'~. ~- &" &" , "', ' ~ .-

becomes delirious and may run full ti lt into fences. Finally it falls over. tltrashes ilS legs in !he air, and dies. Death may oo:;:cur in seven hours 0( st,'eral days. A poslmortem reveals areas of brain necrosis-large. irregular holes whe~ the white matter has disinlegrated.ll was found that the disease condition could be reproduced by feeding the animals com moulded by Fusarium mOlliliforme (the anamorph of Gibberellajuji/.;uroi: Ascomycetes, Hypocreales) , Field outbreaks of this mycotOll:icosis have occurred in Argentina. Brazil, China, Egypt. South Africa and the U.S.A. . but despite Ihe dramatic signs and symptoms it produces. the naNre of the mycotoxin invoked has nOI yet been detennined.

Trichothecenes and Yellow Rain During the Vietnam war the U.S. govemmelll received many reports of chemical

attacks launched by the invading Vietnamese in Laos and Kampuchea against troops and the civilian Hmong people. According to the reports, victims were sprayed with 'yellow rain: an aerosol cont~ining substances with toxic effec ts that d id nOt maleh those of any known agents of chemical warfare. Eventually it was recognized that the symptoms-prolonged vomiting. diarrhea. headaches and dizziness. respiratory problems. blisters. internal haemorrhages. sometimes culminating in death-were like those produced by Ihe trichothccenes. Samples of blood, urine alld body tissues from victims. and leaves. water and soil from sprayed areas were found to conta in several lrichothecenes and zellralenone. typical FrlSariml1 toxins. Control samples. including cereal grains, from areas adjacent to the places where allach had tnken place. contained no frlSQrillm toxins.

However. this issue was clouded by the remoteness of the locatio n. and the unsati s" factory and inconclusive nature of the available evidence. Samples of the 'yellow rain' deposits were later shown to be largely made upof pollen, and it seems probable that these deposits were in iact nothing more than bee faeces. dropped during commullaJ cleansing mgtlts. The issue ... as carefully documented in an anic1e titled Political Science' in The Atlantic Momh/y. lnd I lea\"e you to draw your own conclusions from thaI.

Trichothecenes: Vomitoxin, Refusal and Emesis in Pigs F".mri"," graminearrmr (Fig. 21 .1 B). a common mould on damp corn. produces a

tri chothecene (3.7 .ljtrihydrO.ly1 2.13epoll:ytrichothec9cn-S"one). This has been called \"omilo:!in because it W;l;. first discovered as a resul t of its powerful emetic effect on pigs. which will quickly learn to refuse food contaminated with it. Up to 40 ppm h'le been found in com from Austria. Canada. France.la[Xlo. Sooth Africa and the U.S. It also contaminated barley and winter "heal. Since it affe

r.WCOTOXlNS IN FOOD Al'Io'D FEED 3 11

suspected. Once characterized. the syndrome was quickly linked with the presence of mouldy com in the fecd. and the fungus concerned was found to be the hyphomyccte. Fusarium gmmulearwn (Fig. 21.1 B). The toxin was named ZCGl"alcnonc.IiOOvioo.sly has many of the propenies of oestrogen. one of the principal female SCJ\ honno!"les (it actually seems 10 be involved in regu lating the development of sexual fructifications of the fungus). The toxin doesn 't usually kill the animal. but complications following rectovaginal prolapse some-times cause the whole herd to be destroyed. Lower levels of exposure are also serious in pigs, be

3 12 CHAPTER D VENTYONE

Eventually, in 1963. the e~use of the disease was found to be a to)(in e~lIed sporidcsmin, produced by a saprobie hyphomycete, PithomyceJ dwrtanlm (Fig. 2 1.1 E). growing on dead pans of forage grasses. TIle name of the disease is misleading. ~cause the liver damage. rather than the skin problem, is l ifethrealening. The photosensitivity causing the 'facial eclema' isasecondary symplOtncausedby a pofphyrin, phylloeryth rin. This is a product of chlorophyll digestion that builds up in the peripheral circulation because the damaged liver cannot e)(crete it. Since il would be very expcnsive to spray large oodii: A~m}'cetes. DialX"'rthales). Thi., fungus produces black pycnidial oonidiorn:.ua on st~ms and pods of L"pinus. and the teleomorph has also been relX"'rtcd from this suhstF.l te. TIle fungus is a pathogen that continues growing Sliprobical ly after thc death of thc host, producing toxins in both phases. In Wcstem Australia. where lupinosis is a ~rious problem, attempts are being made to breed lupins resistant to the Plromopsis.

Siaframine: Slobber Factor In the U.S. MidWest. caUle which are seen to slobber or drool. and then refuse to eat,

may well have been feeding OIl red dover (Trifolium) attacked by a stcrik lxIsidionl)'eetoos anamorph. Rhi~OCloni(llegu",injcola (Fig. 21.1 DJ, especially after cool. wet weather. The fung::11 metabolite that produces this reaction was named slafrnmint. It is an acetate estcrof a bicychc amine synthesized partly from lysine. This compound itself is physiologically inactive. bOI is lrunsfo11l1Cd biologically to a quaternary amine similar in activity to ac~tyl choline: thus all choliner:pc c.wcrine gl'lnds are stimulated_ Although we know what causes Ihe disease, il has proved impos.~ible either to breed red do~ resistant 10 the fungus. or (0 cOlltTOl Ihe fungus with fungicidcs. Fonunatdy. there is a simpk answcr- farmers in the midwc,t~m United Stales h~ve givcn up sowing red dover as a forage crop_

Apple Juice and Patulin Patulin firsl attrncted attention as a potential antibactcrial antibiotic isol~led in 19-B

from Pt-Ilicilliwn paw/lim and ~ho from Pf'llicilliltllll'XpmlSllm and Pe,)icillill", c/(IIjforme. as wdl as ,evewl othcr penicillia (Fig. 21.1 A) and asperg illi (Fig. 2 I.! C).lmereSl in ils 3nlib.1clcriai activity h~s now given way to [X)S$iblo:: role as a carcinogen. Penicillium I'xparuum c~us::s a very common Storag.:: rot in apples, SO contamination of apple juice is likely. and should be monitoTt."d. The LD,,, of pamlin in mice is 8-10 mg/kg. Its struetllral formula is gh'en in Fig 21.2.

Tremorgens, the Shakes and Staggers Peopl~ in wo::slem Nigeria are sometimes affiiCled by a condition known as IJesha

Shakes. "fler eating. thq i>eeom

l\.'lYCOTOXINS IN FOOD Al~D FEED' 313

suspected that foods containing ~morgeni-neurotoxins of fungal origin_are respon-sible. A disease of sheep and cattle, known as Grass Staggers, prcsents symptom~ identi -cal to those produced by the tremorgenic toxin penitrcm. A of Penicilliu", eyciopium. There is a strong possibility that the toxins r~ponsible for this disease are prodllced by some sympt,?mless endophytic fungi, inclllding the Acremollilllll anamorph of Epieh/oif ryphina (Ascomycetes, Clavicipitales) or othcr members of this order.

PR Toxin and Blue Cheese You will have noted that many of the mycotoxins discussed in this chapler are

produced by species of Penicillium or Aspergillus (Fig. 21.1 A,C). It so happens that various species of both genera have been used for many years in the preparation of traditional foods. Aspergilli are responsible for many fungally feunented Asian foods, while penicillia impart the uniquc and delicious flavour> to some of our finest cheeses. The conjunction of these facts did not go ullnoticed. Could both Westerners and Asians be insidiously poisoning themselves with these delicacies? Scientists who SCI out to answer Ihat questiOIl were rather dismayed to find that Penicillium raqueforlii, the fungus responsible for all blue cheeses (Roquefort , Gorgonzola, Danish blue, Stilton), did in fact produce u toxin, which they called PR toxin. This substance was lethal 10 mice: when injected intraperitoneally it had an LD", of 6 mglkg. Fortunately for those of us who are addicted to bluc cheese, no trace of this toxin has been found in the cheese itself, and it appears that conditions prevailing during the cheesemaking process prevent to.~in for-mation. It has abo been found that toxins are nOI normally produced during the prepara-tion of soy sauce (shoyu), ketjap, miso, hamanatto, or katsuobushi, all of which involve species of AspergWIIs. ft seems that some kind of selection process has excluded tox i gcnic straills from most food processing applications, or the conditions involv~dJl.a'e inhibited toxin prodllction. However, some cOllcerns remain. Penicilliu", roqllejorrit'has also been found to produce two other toxins, roquefortine and patulin, and Penicilli",>! camembertii, which ripens soft cheescs such as Brie and Camembert, produces cyclopiazonic acid. Whether these toxins are produced in dangcrous quantiti es, or occur at all in cheeses, is not yel fully establi,hed.

Alternaria and Tenuazonic Acid Alternaria (Fig. 21.1 H) is one of the conunonest moulds on various crops . such as

apples ~nd tomatoes, and On deteriorating food, and it i~ now known to produce se\"c r~l mycotoxins, of which the most poisonous is tenuazonic acid. This has been detected in commercial tomato pastes at levels of 0.1 - I ppm, and warrants further attention. In South Africa it has been shown that the growth of nalive cattle is considerably retarded by the presence of tenuazonic acid in their diet.

Cladosporium and Epicladosporic Acid Cladosporium (Fig. 21.1 G) is anotherexlremely common mould of deteriorating plant

malerials, and again produces ~verul mycotoxins. One of tllese, epicladosporic acid , may h~ve been implic~led in the outbreaks of alim

314 CHAPTERTWENTYONE

storage moulds, which n~d only 13% 18% IIl()isrure, This is only a rough division, since some fungi can exploit both ranges, but it gives us some idea (If the kind of conditions to aim for in food storage. Certain aspergilli are the world's most xcrotolerant organisms, capable of growing at e~tremely low water activities (below 0.7), so it is nOl easy to eliminate them romp!etely. Temperature is another imponant factor. The three mOSt im-portant toxigenic mould genera are Pt nicillium, Fusarium and Asptrgillus (Fig. 2 1.1 A C). Theoptimum temperatures for the members of these genera are rather different. Many Fusarium species grow best in thc range 8_15C: the optimum for Ptllicillium species is usually 25-30C: and that for Aspergillus species is often 3Q-4ifC. This infonnation gives us some idea where 10 expect problems with each of these genenl.

A re,em compilation found that representatives of 46 genera of fungi are known to produce mycotoxins. Whcn anamorph-teleomorph connection~ are taken in to account, the number of holomorphic genera decreases to 35. Given that there arc thousands of fungal genera, the number reported as tox igenk seems very low. But is thai so surprising when weronsider that we have detected most ffiy,otoxins only after reacting to repons of toxicit y, and we have not yet taken a pro-active altitude toward testin!; a wide range of fungi for to:o:in production? If and when such a survey is carned out. I predict a dramatic increase in the ranks of the to:o:igenic fungi.

Detection of Mycotoxins The continuous monitoring of food for mycotoxin ,ontamin:uion requires regular

sampling. efficient methods fOfe:l.tracting and purifying myco\o:l.ins. and sensitil'e meth-ods of detecting and quantifying them. Sampling can be a problem. because of the uneven distribution of fl1{}\lld growth (How many mouldy ~anut$ are there in a sack?) i\!ycotox-ins are extr.l,ted with an organ;, soh'ent: ,hloroforT{l, dichloromelhane, acetonitrile. elhyl acetate, acetone or methanol. Repeated column chromatogr.lphic purification is often necessary, using such substances as silica gel. alumina. and Sephadex. Thin layer chromatography (TLC) or high performar!!;e liquid chromatography (HPLC) help in the final separation of thc mycOioxins from other ,om pounds extracted with them.

Af1:uoxins can then be dete

.MYCOTOXINS IN FOOD AND FEED. 3 15

toxin. Chemical tre3tment can give more complete detoxific~tion. Anatoxin~ are de-graded by aqueous solutions of strong acids and bases, so crude edible oils are now treated with NaOH Solulion 10 remo'e anato:o::in. Ammonia treatment will almost elimi_ nate aflatoxin from peanut meal and grains. but may reduce their food value. Oxidizing agents will also destroy aflatoxins: N:lOCI :lnd hydrogen peroxide hold some promise. Bisuiphite, already accepted as an antimicrobial additive in froit juices and dried froits. degrades afl;lloxins. and may become widely used for this purpo:oe if curren! research shows lhal il doesn't damage other food constituents_

Although more mycotoxins are being discovered and chamclerized each year. it seems unlikely thaI we will ever again h:we to rc:son to pilgrimages to give us a vital respite from a mycotoxin-contaminated diet. We should remember. howe'-er. that many people in the underdeveloped countries are still at risk, as are wild and domesticated animals. Mycotoxins may play no dir

Poisonous and Hallucinogenic Mushrooms

22 Introduction

316

A man is brought to the Emergency Department of a hospital suffering from diar-rhea. abdominal cramps, nausea and vomiting. Hi~ problem is diagnosed as gastro-emeri-lis. He is given atropine, donnatal, and intravenous fluids to combat dehydration. then sen! home. The vomiting and diarrhea go on for another 24 hours. By now he is severely dehydrated. and has to be admincd 10 hospital. Over the next IWO days, his li1'cr, kidney and he:u1 begin \0 fail. Despite treatment of his symptoms wilh a b,attery of :lntibiotks. CQrtitosteroids. vitamins. stimulants :l!Id intravenous fluid. he dies.

This is a true story. The only thing I didn't tell you was that the man had eaten 11 meal of wild mushrooms about 12 hours before the onset of his symptoms. By the time you ha' c read this chaptef, you should be able 10 diagnose his illness correctly, and suggest treatm~nl.$ that might have saved his lifc.

People can conveniently be. divided inlo two groups: those who love to eat wild mushrooms. and those who would never dream of doing such a thing. Thcre doesn't se.:m 10 be any middle ground on this issue: )'ou are ~ith~f a 'picker' or a 'kicker." This charac-teristic seem;; to be culturally determined. Most people of Anglo-Saxon origin arc kickers. II hile those from Central and Eastern Europe are pick.ers. Piclting is a p:lstime that occa-sionally gct~ thcm into trouble. There are about 10.000 different spedes of fleshy fungi. The vusl majority arc perfe.;tly innocuous. A rcbtively small number are hunted for theif dehcious flavour. and a cooperative few have been domesticated (see chapter 18). But another few 3re de3dly poisonous. and m:tny Olhers can cau.~e more Of less seriousdiscom-ion iflhey arc unwittingly eaten. During thc course of human history I would suspeCt \hal all 10,000 species of agarics ha,"e been ealen. This chapter considers what we hll\'e Icarned from the trying. tragic or transcendent;!1 experiences ofthosc: who made random Of uncon \ cntional choices of mushroom fOf theif free meal.

The main problem is one ofidemirication. Thcre is no simple rule or tCSt thnt will tell wh~ t her a mushroom is edible or deadly poisonous. MOlly people are blis~ full y un~ aware of this. and rely on tes ts which ore irrelevant and fallaci ou.~. Th~y are playing Rlissian roulelle. You should eat wild mushrooms only if you know, Of can detcnnillc , their !.Cicnlific names. If you are sure. from observation (some of it through thc micro-scope) or cxperience. that all of a particular collection of fungi belongs 10, say. Cantit(lrflhlJ

POISONOUS AND HALLUCINOGENIC MUSHROOMS- 317

Table n.t l\-Iushroom Toxins and their Occurrence Toxins

I. Amanilins (cycJopeptides)

n. Gyromitrin, mooomcthylhydrazine

III. Orcllaninc:

IV, Muscarine

V. IbOlenic add. mu~cimol

VI. Coprine

VII. Psilocybin, psilocin

VI!I. Gastrointestinnl irritants

Fungi

Amanila oisporigera, A. ocreata. A. phnlloides, A. "ema, A. ~iroJa. etc.

Ga/trina autumnolis, G. marginara, etc.: upiotll spp. ConoC)'bt filaris.

G)'romitra bnmnea, G. caroliniarw, G. esculento, G. fastigiala, G, infu~ (?) Hell-ella elastica, (1) H. IaCUIWsa; (1) Poxino spp. Sarcospllilera cro.UQ.

COrrillariUS orelianlls, C. orellanoicks. C. rainierensis.

CliloC)'be cerllssmo. C denlhaw, C. r;,'u/OS(l, C. J,l(/{Jrifica ["oc)'be geophyllo, I. lilnchw. l. pudic

318 CHAPTER TWENTY-TWO

dbariu.l (the chantere]]e: Fig_ 5.5 0), or Morchella escu/elila (the morel: Fig. 22.1 C), and IhJt the fruit bodies are young a!ld freshly picked, experience tells us that you can eat a!ld enjoy them. as mycophugists have done fOf thousands of years (though some people are aliergic to mushrooms). Every year, many people take unnecessary chances by eating unfamiliar mushrooms, or confuse poisonous species with edible ones, and every year some unfortunates are fatally poisoned.

Since most North Americans afe kickers, they lend not to become mushroom poi-soning statistics_ Europea!ls, however, are pickers, and have suffered as many as 100 fatalities in two weeks. In 1975, a Swiss newspaper reported 54 local deaths during a short period in late summer. Which fungi killed these people? What are the toxins involved? We recognize eight different kinds of mushroom poisoning, which are listed in Table 22. 1. A quick look at this table will show Ihat fatalities arc usually caused only by groups I, II and III. In fact, 50% of all serious mushroom poisonings, and 95% of all fatalities, are caused by members of a single genus. Amanita, Which fruits in late summer and falL

A: A_~il~ vJros:> I. m.",,)

Fig. 22.1 The deadly and the deliciollS.

B: OaJ.,ina ~vlum"aJJs lam." ,,")

0 : Gyramflr" .u"r.M' IS,,,,"',i"-MMK)

C Idarcl>~/J~ UC"IMI~

~~ UFPE-CC1/il' 2'

POISOi"iOUS Ai"D HALLUCL"OGENIC !\'IUSHROOMS' 319

Group I- Amanitin Poisoning As a resull of m:lJly inadvenenl, and often fatal. experiments made by hapless or

foolhardy volunteers, we can say thai the basidiomata of several spedes of the agaric genera Am.llllira and Galerirlll (Fig. 22.1 B) contain toAins that are lelhal 10 humans in extremely small doses. Amanita rirolQ (the 'destroying angel': Fig. 22.1 A), Am.llnita phal/oidel (the 'death cap' ), and closely related species are notorious killers , They con-tain such high levels of to;(in that a single bite can be fatal 10 a debilitated individual. The to;( in molecules are made up of amino-acids in a double ring, and so are called cyclic oligopeptides or cydopeptides, They come in two varieties, known as amatoxlns (aman-itins), which contain 8 amino-acid molecules, and phallotoxins (phalloidins), which contain 7 amino-acid molecules. When injected inlO mice, the phallotollins are ten limes more le thal th~ n cyanide: their LD)(l is 2 mglkg. But when taken by mouth, they have no eff~t. They may be neutralized or broken down by digestive juices, or may not be ab-sorbed by Ihe gut. in contrast, the much more deadly amato;(ins are actively toxic when eaten (LD~ " 0,1 mg'ki).

Amato;(ins rapidly dnmage intestine, kidney and liver. Alpha-amanitin attacks the nucleus of cells, binding to RNA-polymerase II, the enzyme that transcribes DNA and produces messenger RNA. The synthesis or RNA ceascs, and so, as a direct consequence, docs the synthesis of protdn. This ultimately brings the IlliIchinery of the cell 10 a stand-still, and it dies. Cells of the intestinal lining, liver and kidney ha,'e a rapid turnover, SO their loss and non-replacement will soon ha"e serious efrects on the organism, This is bad news, but there is worse to come. we still have no speci fic untidote to these to;(ins. And worst of all, the outward symptoms of am:;uO)l:in poisoning do not begin until after a great deal of the cell damage has been done. This m~kes it one of the most difficult forms of poisoning 10 treat.

Onc imponant step in understanding what may be going on in a poisoning case is to ascertain whether the mushrooms in the case contain amato;(ins. The l\'lcixner test pro-vides a simple way of doing this. Liquid is expressed from a piece of the fresh mUShroom into a circle marked on a piece of ne,,spaptr. and allowed lo dfY (perhaps with a linle help from a hair-dryer), A drop of conccnttated hydrochloric acid is added to the dried spot. A blue colour, developing at any time over the ne;(t 20 minutes. indicatcs the prcsence of amato;(ins. If the to;(in is prescnt in Ihe agaric at high levels, the colour will probably de"clop in 1-2 minutes, Newsprint must be used. r(llher than high-quality paper, because the test is based on a reaction between amatoxin and lignin. which is catalyzed by the add. A negative test does not pro"e tbat an al!ar1c is edible.

The most !X'i.~onous mushroom in eastern North America is prob.lbly Allumila I"irosa. The large basidiomata of this innocent-looking species arc pure white throughout, and have both ring and vol\a. in the Wesl, the siruation is complicated by the preseoce of Amllnita pl1C1I/oide$. with a grcen;~h cap. which is probably just as to;(ic as A. V;roSli. Those who have eaten these species re port that lhey have a mild navollr. SubseqLlent events may be divided into foor stages. (I ) A latent period of 624 hours, most commonly about 12 houn;. This asymptomatic interlude is long enough that the patient frequcntly does not even connect the subsequent illness with mushrooms. During this hiatus.the amanitin is anacking the cells of the Ih'ef. kidney and intestine. (2) Violent vomiting, dimhea and abdominal pain, ",hich last for aday or so. (3)A brief, misleading remission of symptomS. (4) Collapse of kidney and liver function, with secondary effects on the heart and brain, leading to com(l and dea1h.

What can be done for ViCliI!ls of aman;tin poisoning? TIle biggest problem is the long delay in the appearance of oven symptoms. By the time the patient seeks medical

320 CHAPTERT\\'ENTY-T\rO

aid, mas.,;ve cell damage m.l~ :Il ready have been done. Thc first hurdle is to .lmve at a correct diagnosis. Amanita poi.oning is relatively nU"c in Nonh America. and many doc-tors may not think of il unless the patient mentions mushrooms. Even then. moSt phY5i-cians (and this is no discredit to them) know vinually nothing about diagnosing mush-rooms. No identifiable specimen~ may be available. \\~th luck, the local mycologiSt will be called in, and will recognize the danger inherent in the delayed symptom~. Even if the prob lem is correctly diagnoStd. there is current ly no antidote for amanitin. Treatment consists of attempts to; (I) remo,e toxin from the system: (2) increase the rate at which the p;:llient excreteS it; (3) suppan the patien( s various s)stems.

(I) Removal of toxin. If the conditinn is diagnosed within an hour or two, it is obviously appropriate to empty the stomach by emesis and gastric lavage (getting the patient to throw up. and then "'ashing out the stomach). If the usua1latent ~riod has elapsed, this approach would be pointless. Three blood-cleansing techniques have been applied to late-diagnoscd amanitin poisnning. (A) HacOlodialysis (circulating the blood th rough a semipenncable membrane bathed in an isotOnit medium) is used in longtenn tRatment of kidncy failure, or until a transplant becomes available. It s use in Amanita poisoning is questionable, since it rcmo\es substances of molecular weight 300 or less. Amanitin ilsdfhas a molecullr weight of9OO, and it may often become complcxcd with much larger molecules, such 1S proteins. Neverthcless. in serious cases, where kidney failure threatens. haemodialysis may be useful under heading 3. (8) Haemopcrfusion (circul;uing the blood over a~tivated cil:trt"oal) is used to support the detoxifying func-tion of ailing livers. [! has been used cxp.:rimentally to treat Amall ila poisoning in recent years. ~nd has been shown to r~movc some toxin fro m amanitin-spiked blood.

Unfonunately, the amounts of amanitin delected in the blood of poisoning victims are usually very low, especi aJl~ if more thln 12 hours havc elapsed since the mushrooms were eaten. Keeping in mind the possible unfavourabk effect of haemoperfusioll on a blood coagulatory pattern alre.ldy unbabnccd by the effec ts of the loxin, this technique should be applied wilh

POISONOUS AI'ID HALLUCINOGENIC MUSHROmlS 321

The Bastien Treatment. A French physician. Dr. P. Bastien. has developed a new treatment for Amaniw poisoning. It has three p:ltts: (I) inuavenous injections of I gram vitamin C twice a day; (2) tWO caps ... les of nifuroxazide three times a day; (3) two tablets of dihydrostreptomycin three times a day. The treatmenl is supplementcd by measures (0 control fluid und electrolyle balance, and by penicillin. Ba.~tien suC'Ce~sfully treated 15 cases of A. phalloidel poisoning between 1957 and 1969. In 1974 he au: 65 grams of A. ph

322 CHAPTER TWE/'IriiY-TWO

system, irritates the gaslro-intestinal tract, and damages the liver. Methaemoglobin and free haemoglobin are present in the blood. Levels of bilirubin and livcrenzymcs rise, and blood sugar falls. Unless the tox ic nature of the mushroom is diagnosed almost immedi-ately arler il has been eaten, there is linle point in evacuating the gut. Pyridoxine hydro-chloride should be administered as a spedfic phySiological antagonist of MMH. The patient's blood sugar, liver and kidney function, and free haemoglobin level should be monitored. intravenous glucose. foreed diu resis if free haemoglobin rises. haemodialysis in severe cases, and other supportive measures, may be needed.

Group III: Orellanine Poisoning in 1957 a report emerged from Poland of Iltree outbreaks of mushroom poisoning

caused by eating Coninorius ordlal1lu. Among 132 people poisoned, ]9 died. Death was caused by kidney failure, and in most cases occurred IWO to three weeks afler symptoms begnn (though some children died within a few days, and other deaths were delayed for months). The most unusual feature of this poiSOning was the e:ltremely delayed onset of symptoms. Even in severe nnd ultimately fatal cases, no symptoms were reported until 3-4 days after the mushrooms had been eaten. In milder cases, tbe latent period was longer, extending to 10-17 days.

initial symptoms were an intense thirst. accompanied by burning and dryness of the mouth. Headache. chills, loin or abdominal pain, nausea and vomiting followed. Al-though urination was initialiy stimulated, it was soon reduced and in some cnses ceased altogether. 111. serious cases, tbe BUN (blood urea nitrogen) rose. as might be expected following kidney damage.

Once this form of poisoning had been recognized and described. it was reported from France. Germany, Switzerland. and CzC{;hoslovakia. No confirmed cases hal'e been reported in North Amo:rica. The nephrolOxin involved is called ordlanine. and bas been detected in another European species. Corrinarius ore/lanoides. as well as in the North American species, Cortinorius roiniefensis. QrelJanine has an oral LD", (cat) of 4.9 mg! kg. It is estimated that 100-200 g of fresh C. ore/lal1(1.r contains enough orellanine to cause complete kidno:y failure . Although there do nOt appear to be any reports of kidney transplants in the Iiter::tturc, tbat procedure would now seem to be an appropriate response to total renal shutdown.

Group IV: Co prine (Antabuse-like) Poisoning This kind of poisoning c;an occur at any time fOT up to 5 days after Coprinus

alMmeTllarius (Fig. 22.2 A) has been ealen. Strangely enough, tbe mushrooms by them-selves arc not toxic. Symptoms appear 30-60 minutes after the mushroom-eater has a drink containing alcohol : they include hot flushes of the face and neck, a mctallic taste in the mouth. tingling sensations in the limbs, numbness in the hUllds, pnlpit~tions, a throb-bing beadache. nausea and vomiting, Thi~ is an unpleasant combinalion. but il isn't fatal. The only treatment necessary may be to control arrhythmia (irregular heartbeat). The syndrome will persist as long ns there is any alcohOl in the system- usually 2-4 hour.;-after which recovery is spontaneous. and the victim may well Swear off booze.

The condition arises because Coprinus a/ramentarius contains coprine, a unique ~mino acid thJt blocks the metnoolism of ethyl alcohol at the acet3!dehyde stage. Coprine poisoning is renlly ace taldehyde poisoning. The ratber excess ive duration of this poten-tia] booby-trap for drinkers is due to the persistence of coprine in the body. Antabusc (disulfiram). which is prescribed 10 help alcoholics stay on the wagon, bas an aClion almost identienllo that of coprine. though the two substances are chemicaHy different.

POISONOUS AND lL\ .LLUCINOGENIC MUSHROmIS' 323

Group V: Muscarine Poisoning-PSl Syndrome II is a good idea to avoid eating linle white or brown mushrooms that grow in the

grass. since some members of two common genera, ClitQcybe (Fig. 22.2 B) and Inocybe (Fig. 22.2 C), contain significant amounts of muscaruJe. This is a toxin that. within 30 minutes to 2 hours of being consumed. stimulates the exocrine glands-the producers of sweat, saliva and tears-in what is called the 'PSL' syndrome (perspiration. salivation, lachrymation), and also causes constriction of the pupils, blurred vision. muscle sp:l:Sms. diarrftea. slow heanbeat. and a drop in blood pressure. Theonly real danger here is that the heart may actually stop. if enough toxin has been absorbed. This has happened only rarely, and then in p;ltients with existing cardiovascular disease. The appropriate rreat-ment is carefully administered intravenous atropine.

o """"';1.0 ""' .. ,.;., (;t>oc..,;o "",,, """"""'1

Fig. 22.2 Mushr{)()rT1$ that make )OJ feel strange.

E: 1'$#0

324 CHAPTER TWENTY-TWO

Group VI: Ibotenic Acid-M uscimol Poisoning Earlier in this chapler, r described what happens when someone cats the deadly

species of Amanita, those containing amatoxins. But other spee ie~ of Amanita produce ycry different effects. Amanita mU$caria (Fig. 22.2 D), the famous scarlet-capped, whlle-spolled mushroom so beloved of fairy-tale illustrator.>, is one of these, It induces muscle spasms, dizziness (and Yomiting, if too many mushrooms have becn eaten), then a deep sleep full of fantastic dreams, lasting about 2 hours. On waking. the ~ubject u>ually experiences a 'good trip': a feeling of elation that persists for several hours. People often become hyperactive, making compulsive and uncoordinated movements, perhaps talk-ing non-stop, and having altered perceptions of reality. Occasionally the experience is a 'downer.' Clearly, Amanita mllscaria contains a substance that specifically affects the central n~rvous system. Needless to say, thi:; was discovered long ago, and has been exploited by various peoples. The Soma hymns of the 3,OOO-year-old sacred Indian book, the Rig Veda, have been interpreted as a glorification of A. IIIlIscaria and its effects. Many tribes in Siberia u~d i[ forc~nlL1ries as a religious Of recreational intoxicant, and although ;t has now largely been replaced by vodka. some Siberians still prefer mushrooms.

Historical accounts suggest Ihm the nct ive principle is not destroyed in the body, but;s excreted lmaltered in the urine. Probably by watching their reindeer, which have a fondness for urine, the Siberians learned thm the inebriant could be recycled. When mushrooms were in short supply. and only the richer tribesmen could afford them, the poor folk waited for the guests to relieve themselves. then drank the intoxicating liquid. Clearly. the motivation was very strong.

Although fre>h mushrooms cont. Although very few deJths have been reported from this kind of poisoning, 10 or more mushrooms can conslituk a fatal dose.

In most cases, the best treatment is no treatment. Recovery is spontaneous and compl ,,[~ with in 24 hours. If many mushrooms have been eaten, severe convulsions may hal'c to be controlled, and the stomach should be emptied. On no account should atropine be givcn: it will exacerbate the symptoms.

Group VII: Psilocybin-Psilocin 'Poisoning' -Teonanacatl' - 'the flesh of thc God;;.'This is how theAztecsofMcxicodescriOCd the

sacred mushrooms which have been used for thousands of years in Central America for religious rite~ of divining and curing. The practice was supp l'~ssed by the 'Christian' Sp~n ish Conquistadors, and the secret of Teon~nacatl was lost to the outside world until the tw~ntieth century. The story of its rediscovery is a mycologic~l classic. After penetrating the wall of silence with which the people of Oaxaca protected their shamanic ceremonies, IWO Am~ricans wcre el'elllually allowed to participate, and to partilke of the sacred mushrooms. Aft~r ~ating the mushrooms, thl tOrs vOmile(1. Again they waited. Nothing happened Th

POISONOUS ANn HALLUCINOGENIC MUSHROOMS- 325

which your body lits. heavy a~ lead. on the maL and you take nOtes and COmpare experi_ ences with your neighbour. while your soul flies 01I to the ends of the world and, indd. to other planes of existence_ .. some seem to experience only a divine euphoria. which may translate itself into uncontrollable 13ughter ... 1 experienced hallucinations ... vision~ of palaces, gardens. seascapcs, and mountains .. ,. With the speed of thought you arc translated wherever YOi.l desire to be, and you are there, a di~embodied eye, poised in sp~ce . seeing. not scen. invisible. incorporeal. I have placed stress on the visual hallucina_ tions. but all the senses are equally affected, and the human organism as a whole is lifted to a plane of intense experience. (Everyday experiences are) transformed. leaving you breaLltless with wonder and delight. The emolions and intellect are similarly stepped up. Your whole being is aquiver with life:

Experiences like these can be triggered by members off OUT agaric genera: PsilO('ybe (Fig. 22.2 E). P(III1UQ/U.f, Conocybe, and GylltnopilllS. The Mexican rites usually employ one of several P.li/ocybe species. particularly P. caeruleJcens. P. lapotecomllt and P. mexicana. In the United States. and in coastal areas of BritiSh Columbia, devotees of 'magic mushrooms' orten wllect hallucinogenic species of Palllle()lus and Cont)Cybe. Psilocybe species are often cultivated. since spore prints of. for example. P5iloc)'be clIbmsis (fig. 22.2 E) can be ordeted by mail. and people in the Pacific Nonhwest avidly hum for Psi/O('ybe semilnncem(l and P pl'llicula. which are the fabled 'I ibeny caps.' The psycho-ac tive principles in these agarics are indole alkaloids called psilocybin and psilocin. hydroxyltryptamine derivatives related to the neurotransmitter. serotonin. An average effective dose of psilocybin is 4-8 mg. the amoUIlI contained in about 2 g of dried mush-rooms. If larger qll(lOtities of mushrooms are e~ten. the halli.lcinogenic effects may be rather overwhelming. but serious poironing is unlikely unless huge numbers of mUSh-rooms aIe consumed. Adults on 'bad trips' may become cxtremely anxious or even par3-noid. and may need considerable reassuronce or, more nudy. tronquilizers. Children who eal hallucinogenic mushrooms may develop a high fever or convulsioll. They should nol be given aspirin. Tepid baths or wet sheels should be u!>Cd. Hallucinations may be sup-pressed by chlorpromazine. and convulsions by diazepam.

Group VIII : Gastro-Intestinal Irritants The seven kinds of poisoning aln!ady described arc now fairly well understOCld. Most

of the relatively fcw fungi involved are clcarly identified as containing specific toxins which cause well-defined sets of symptoms. In contr.lst. the se"enth kind of poisoning is caused by a grob-b:lg of fleshy fungi belonging \0 many different gencra They have only one thing in common: within 30-90 minutes of being eaten. all causc various degrees of digestive upset. The commonest symptoms are vomiting and diarrhea. with abdominal cramps. Fortunately. the similarity to amanitin poisoning ends there. Symptoms generally clear up sponta!'l~'()usly in 3-4 hours. and complete recovery takes only a day or so.

Littlc or lIothing is known about the to.lin$ involv~d, though the diversity of fungi eall5ing these symptoms suggests thaI a number of diffacnt substances may eventually be implicated. Digestive disturbances can be caused by various members of the following genera: Agaricus. Amalliw. 8o/ellls. CMorophyllllm. Elltoloma. Hebelcmlll. Lacrarius. Milrasm;/Is. Nacmmoloma . OmphalOlllS. PltolioTa. Russilla. Sdemdemw. TrichQ/(Jma. and possibly many others. Since we don't know" hal chemicals are {':uusing the problem. treatment is restricted to empty ing the stomach and, in elderly or debilitated patiems. monilOring for dehydration. reduced blood pressure or impaired kidney function . OcC3 sional fatalities have been caused by almost oil of these fungi.

If we look back on the various kinds of poisoning examincd in this chapter. Jnd try to analyze the mechanisms involved, we can discern four basic p>lltems:

326 CHAPTER TWENTY-TWO

(I) Toxins thnl cause exten

IJ.f, UfPECCB @ BIBLI01ECA

Medical Mycology

Introduction

23 Three rather different groups of fungi actually cause spedfit diseases. A few obli-

gatc!y pardsi!ic fungi (dcnnatophytes) have evolved specifically to onoek the omer sur_ face of human beings. A few other fungi which callse disease ill people are normally soil organisms, but have also adapted to life in the unusual and rather hostile environment of the human body. often responding to this environment by developing a different mor_ phology (thermal dimorphic saprobes). A third group of opportunistic saprobcs can auaek 1,15 only when OUf defenses arc: down-wiltn OUf immune systems themsel vcs arc: diseased or deficient. or when \Io'C artificially suppress mem. as we mUSllO prevent the rejection of transplanted organs.

We can divide fungal auacks on our persons illlo: (I) cu taneous infections, which involve the outer lay~fs of the skin and cause an allergic or inflammatory response; (2) subeuhlll~ous infections, usually involving fungi of low inherelll virulence which have been introduced to the tissues through a wound of some kind, and which remain localized or spread only by direct mycelial growth; and (3) systemic infections, whic h afe cau;cd, either by true pathogenic fungi which can establish themselves in normal hosts, Of by opponunistic saprobic fungi which could nOt infect a healthy host. but can anad: indio viduals whose immune system is not working. Both kinds of fungi sometimes become widely disseminated through the body of the host

Cutaneous Infections Most cutaneous mycoses arc caused by a spccialiled group of kerminoiylic fungi

called the d crmatophytes, of which you hal'e already learned something. There are about 40 spe

328 CHAPTERn\'E1\TI'-THREE

to dogs o r hl.lmans. bl.l t will die Ol.lt after one or two perso ll -to-person transfers. If it i~ to 5urviH', il must return to the cat for tejuven:uion. About five sptcies Me recorded from both man and animals. The irrit:uion caused by the presence of the fungus stimulales the epithelial cells of tIle host to divide more often than usual. This increases the amount o f keratin availabk to the fungu s. und also means that more flakes of skin containing infec_ li\e mycelium will be shed. Epid(nnophy/ol'! floa;osum causes transielll infections, and relies on this nfolialed material for quick spread 10 Other hosts. Tric/lOpfrylorl. rubn,m tends to ca l.lse chronic infection5 of the foot and tOenails. so the host produces infect ive materi ~1 over a period of years, Almost everyon~ is susceptible to short-tenn infection b>' Epid(nnqphylOl1 floccosum, but a chronic Trichophytol'! nrbrum infection of one mar-ri.:lge partne r m~y never be transmi tted to the other. TrichophylO'l collcemricllm cau~es a chronic ri ngwonn of the body in Polynesians (tinea imbriC2ta. tokel~u). bllt is never tr;ln~milled to caucasians or blacks living in the same communities . Trichophrton rubmm can anack any pan of the skin, but Microsp()ntm aldOifini; and Trichophyton tollSfmms are found mainly on the he ~d (tinea capitis), and Epidennophyton flocc().lUm usually infec t. the fC(:{ (tinea ped i~, athle te 's foot) or the groin (ti nea cruris, j ock itch). It must be emphasized that these fungi are not growing on living tissue. Their clinical effects are due to the various irritants they produce: enzymes su

L\ IEDlCAL L\ IYCOLOG Y .329

lates the formation of a tumour. within "hich are many compact fungal colonies called grains. If the surfact of the skin t" entually ruprures. some of these colonies may be extruded. They have been found to belong to fungi such as ,\1adurelfa mycelOmm; . (Hyphomycetc$). Exaphiala jea"seimti (H~'phonlycc tes), PW lda/ltschtria boydii (As-comycetes) and LeplOsphlleria S/!"egalellSis (Ascomycetes).

Sporotrichosis is caus~d by SpOfOli!ri.T schem;kii. a co

330 CHAPTER TWENTY-THREE

southwest U.S. have contracted the disease. Fortunately, as in histoplasmosis, mo,t cases are benign, and healing is spontaneous. A few become systemic, and are usually fatal if untreated or misdiagnosed. The disseminated form of this disease is commoner among males than females , and among people with darkly pigmented skin.

(3) Paracoccidioidomycosis is a disease exclusive to Central and South America. It is caused by Paracaccidioides brasiliensis, which seems to occur mainly in tropical mountain forests. Inhalation of conidia causes a primary infection in the lungs. However, as with the other two diseases just discussed, though infection is corrunon in endemic areas. serious disease is rare . When secondary infections do occur, they tend to provoke ulceration of the mucosa of mouth and nose, often causing loss of teeth. Less conunonly, the pulmonary infection progresses, mimicking tuberculosis, and sometimes eventually involves other internal organs. [n the host. the fungl.ls occurs as large, ml.lltipolar bl.ldding yeast cells (cf. Fig. 6.1 A), while in culture it is a mycelial, Chrysosporium-like anamorph (d. Fig. 4. 11 F). The tclcomorph, if one exists. has not been di,covered.

(4) B[astomycosis is caused by Blastomyces dermatWdis, a fungl.ls rarely isolated in culture from soil or other natural substrates. However, the diseasc is endemic to several areas , induding the Eastern U.S. and Canada. Infection often seems to be a n::stlit of disturbing plant debris. Again, th~ primary infection is in the lungs. forming large granu-lomas that contain many tiny abscesses. These lesions may heal, but the organism then crops up in another area, frequently the exposed parts of the facc and neck. Warty, thick~ ened patches develop, which spread widely and cause e.\tensive scarring and destruction of tissue. Internally. bones may become inyolved. Eventually other organs, especially the proswte ,md the brain. are atwcked. Blastomyces is seen as a yeast cell in host tissue, but forms a Chl)'sosporium-like anamorph in culture, converting to a yeast-like form at 37'C. Mating of compatible strains produces the tcleomorph, Ajellomyces dermatirjdjs (Asco-mycetes)

Opportunistic Pathogens Opportuni

MEOICALMYCOLOCY 331

Zysomycosis is caused by se~eral opportunistic members of the Mucorales (Zygomycota). Rlrizopus orrlrizu$ and Rlri:oplts of)'UI~ are mo&t commonJ y in~oh'ed, but s~ies of Muco r, Rhizvnrucor and Absidia have also been reponed. Four kinds of sys-temic disease occur: rhinot'erebral, thoracic, gastro-intestinal, and cutaneous. Rhinocerebral zygomycosis attacks acidotic diabetics (who have high blood sugar, high ketone levels. and usually some leucocyte dysfunction). The infection begins in the sinuses, then grows with dramatic rapidity outward to the eyes and inward 10 the blain. The eyes bulge and may become paralysed. the eyelids droop. and there is often some degree of facial para!>'-sis. The disease usuaHy progresses with devastating rapidity, and is of len fatal within 7 days.

Thoracic zygomycosis strikes people with leukemia or lymphoma. and occasion-ally also diabetics, lraIl.>plant patients undergoing steroid therapy, or patietUs on dialysis. The symptoms are those of bronchi tis and pneumonia. wilh complications like thrombo-sis or infarction, caused by direct invasion of blood v~,ssel s by the fUngus. This disease is also fatal if untreated_

Gasrroimestimlzygomycosis almost always occurs in ThirdWorid coumries, at-tacking children who art' already suffering from Kwashiorkor (chronic protein deficiency). The causal agent, Ab$idia cOf)?1Ibifuu (Zygomycetes), invades the wails of the stomach and ime~ tine, blocking the arteries. The resulting necrosis and perforations are fatal. CutaneQUS zygomycosis occurs when zygomycetous fungi colonize bums. In a severely burned, and the refore extremely debilitated, patient, the infec tion may spread rapidly and be quickl)' fatal.

Cryptococcosis is caused by an encapsulated. budding basidiomycetous yea;;t. Cryptv('OCCUJ ncojonmm,,!, the anamorph of filvoosidiella neojvm,ans (Aphyllophoralesl_ The anamorph commonly grows on pigcon droppings, so everyone is eXpVscd to thc propagulcs of the fungus. Many people contract sub-clinical or asymptomatic cryptococcusis which r~sol\'es spontaneously. An unfortunate minority, often already suffering from leukemia or !)'mphoma. or on immunosuppressive therapy following or-gan transplants, dewlop lung disease which may thcn become systemic, This phase involves bones, or organs such as hean. testicle. prostal

332 CRAYTER n YEl";iY-THREE

AIDS and Mycoses Since the searing advent of AIDS-Acquired Immune Deficiency Syndrome-to

our societal consciousness, medical mycologists h(lve become aware that many AIDS patients suffer from a variety of mycoses. Patients who developed certain opportunis tic mycoses in the absence of any obvious predisposing (acton were automatically Investi-gated 10 see whether they also had AlDS. The "diagnostic" mycoses included Aspergillo_ sis, Candidiasis, Cryptococcosis, and Zygomycosis. Oesopbageal candidia ~is and cryptococcosis of the central rtervOU5 system were regarded as being particularly strong indicators of AIDS. Candidiasis of mucous membranes is seen in two-thirds of AIDS patients. Cryptococcosis is fou nd in 6- 10% of AfOS patients in NonhAmeri1;:a . but in onc-third of patients in Zair

MEDICAL MYCOLOGY 333

America, mOM people will never contract a serious mycosis. You are far more likely to come to grief crossing the rood. riding your bicycle. or cooking dinner. But you will most probably be infected severaltimcs during your life by dermalophytcs.

Further Reading Ainswonh. G.c. and P.K.C. AuslWick(1973) fungal Diseases Or Animals_ 2nd Edn. Com~

monwealth Agrkultural Bureau:.:, Slough.

Campbell, C.K. and a.c. While (1989) Fungal infection in AIDS patients. The Mycolo-gist 3(1): 7-9.

Delacrctaz, 1 .. D. Grigoriu and G. Ducel (1976) Color Atlas of Medical Mycology. Hans Huber, Bern.

Emmons, C.w. , C.H. Binford, J.P. Utz and KJ . Kwo n-Cbung (1977) Medica l Mycology. Lea and Febiger, Phi ladelphia.

Rippon, 1.W. (1988) Medical Mycology. 3rd Edn. Saunders, Philadelphia. Speller, D.C.E. (1980) Antirungal Chemotherapy. Wiley, New York.

Vanden Bossche, H., D.W.R. Mackenzie and a. Cauwenbergh (1987) Aspergillus and Aspergillosis. Plenum. New York.

The CD-ROM which accompanies this book has many illustrations of dise~s caused by fungi-just look a1 chapter 23.

-

: UFPE-CCI!> I!$BIl3U01ECf:,

Commercial Exploitation of Fungal Metabolites

24 AI the end of the twentieth century. exploi tation is something of II dirty word. Ex-

ploiting people means laking advantage of them in some way - of their gullibility. gIttd. need or weakness. Exploi ting niltura! resoulU:s has oome, a]lloo often, 10 mean depleting th~m (think of OUf forests ilnd fisheries). However. I don 'I think we need wOlT)' 100 much about exploiting most fungi. al least the ones that grow in pure culture. They are in many COStS il prime e xample of il rencwuble resource, always ready to germinate from an almost mfm i!c i>Upply of spores or hyphal inoculum, ahle 10 grow on a wide range ofm:uerial-, that are generally regarded as surplus to human requirements, such as bagussc (what is left of sugar cane after the sugar has been c;.;tracted), and :u rnc:d with II broad spectrum of biodegradative and synth etil an;hof 1942.Anne Shcafe "'tiller was dying from a streptococcal infcction. Her tcmpcruture npproached 10TF and she was delirious. O\'~r the course of a month. the

COi\'fi\rERCTAL EXPLOITATION OF FUNGAL METABOLITES' 335

doctors in New Haven, Connecticut, had tried sulfa drugs , blood transfusions and surgery, all witho .. t s .. ccess, It seemed that the StreptocofXUS bacterium was about to claim an-other victim, But j"sl as all appeared lost, her doctors managed to get hold of a recently purified fungal metabolite called penicillin - named for thc Penicillium mould that produced it _ and administered it to Anne. SOOIl her temperature fell, she emerged from her delirium, and began eating again. Her hospital chart recording these events is now in the Smithsonian. Fig. 24.1 shows Anne with the serendipitous original discoverer of penicillin. Sir Alexander A eming. Anne was fortunate in her doctors and in her timing (the right patient, in the right place, at the right time ... ) We should all be so lucky!

Many readers may not have known about Anne, but most people have heard of Sir Alexander Fleming. Although penicillin didn't ~ave a life until 1942. it was discovered 13 years earlier, in 1927, and the concept of antibiosis had been noted as early as 1881 by another English microbiologist, John Tyndall, who recorded that culture media that had become cloudy with bacterial growth sometimes clcmed when moulds grew on the sur-face. {n 1927 Fleming was growing p .. re colonies of Swpliy/OCOCCUI aureus on plates of culture medium when one of the plates became contaminated by a mould. A wide dear wne around the fungal colony showed Fleming that something was diffusing out from the mould and killing or inhibiting the bacteria. He isolat~d the mould and found that it was a species of Penicillium, P. IWfamm. So Fleming named the unknown substance penicillin and brought it to the attention of other scientists. Although he published an account of his investigation (British Jm,mal of Experimental Pathology 10: 226, 1929) .

. 24.1 A historic phologrJph of the fo-st patient cured by peniciRin, with Alexander F1emng,

336 CIIAPTER TWE1''TI'fOUR

Fleming did not pursue the nt:ltter, and il was lehto Others to isolate penicillin, tc:Sf it agains t bacferia inside humans, and demonstrate how relatively non~toxic it was.

This brings us to the crucial test of antibiosis. There arc lots of substances that will kill bacteria stone dead. but aimosl all of them will also kill the host organism as well. Scientists needed something thai was far more dmnaging to bacteria than it was to people. They found il in penicillin. at least for Gram.positive bacteria like Staphylococcus. By 1941. measurable quantities of penicillin had been isolated. and the crude extract was used to treat an Ollford policeman who had a pOtenlially fatal staphylooocral infection. For SCIeral days he rallied. but then th~ supplies of penicillin ran out. and he relapsed and died. By now. the Americans had been drawn into the war by the attack on Pearl Harbour, and the need for antibiotics to treat wounded servicemc:n he

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