studies on the molecular ecology of blastomyces dematitidis

对于分子生态学领域的同行希望有所帮助。

Mycopathologia152:51–58,2000.

©2001KluwerAcademicPublishers.PrintedintheNetherlands.

51

StudiesonthemolecularecologyofBlastomycesdermatitidis

DennisJ.Baumgardner1&BryanLaundre2

1Department

ofFamilyMedicine,UniversityofWisconsinMedicalSchool,Milwaukee,WI,USA;2Universityof

WisconsinMedicalSchool,Madison,WI,USA

Received31January2001;acceptedin nalform11July2001

Abstract

ThemicroecologyofBlastomycesdermatitidis,thedimorphicetiologicagentofthepotentiallyfatalsystemicfungalinfection,blastomycosis,isnotwellde ned.Blastomycesdermatitidismayoccurperiodicallyatnaturalsites,perhapsaidedbyrottingorganicmaterial,animaldroppingsandphysicalchanges.Semi-quantitativegrowthstudiesofB.dermatitidison2%agarplatesdeterminedtheabilitytoutilizeortolerateavarietyofsubstratesincludingsimpleandcomplexmoleculesascarbonsource,andorganicandinorganicnitrogensources.Allantoin,creatinine,quanidoaceticacid,guanidineandcysteinemaybeusedassolenitrogensource.Allantoinincombin-ationwithdextrose,glycerol,lichenen,celloboiseandotherwoodby-productssupportgrowthofB.dermatitidisatroomtemperature.Thenutritionalconversionofthefungustotheyeastformatroomtemperature,welldemon-stratedonallantoin/glycerol/yeastextractmedia,appearstobeaffectedbycertaininorganiccompounds.Theorganismtolerateslowtomoderatelevelsofalpha-pinene,tannicacid,shikimicacid,veratrylalcohol,vanillicacid,andpolyethyleneglycol-200.Therearesigni cantdifferencesamongisolatesregardinggrowthonvarioussubstancesat20 and37 centigrade.Itappearsthatavarietyofwoodby-productsandanimalwastesubstrates,incombination,supportthegrowthofB.dermatitidis.TheirroleintheecologicalnicheofB.dermatitidis,andtheimportanceofnutritionaldimorphisminthenaturalenvironmentwarrantsfurtherinvestigation.Keywords:blastomycosis,Blastomycesdermatitidis,dimorphism,ecology

Introduction

Blastomycosis[1,2],asystemicandcutaneousfungalinfectionofhumans,dogsandotheranimals,isfoundinportionsofNorthAmerica,AfricaandIndia.InNorthAmerica,theendemicareaappearstobespread-ingnorthwardandwestward,nowincludingColorado[3].Inmostareas,thediseaseoccurspredomin-antlyinindividualsassociatedwithruralagricultural,recreational,orwildernessenvironments.

Humanandotheranimalinfectionstypicallyoc-curfollowinginhalationofconidiaofthedimorphicetiologicagent,Blastomycesdermatitidis,andtrans-formationtotheyeastforminthelungs.

ThepreciseecologicalnicheofB.dermatitidisre-mainsunde ned.Thephysicalgeographyofhighlyendemicareasarecharacterizedbypodzolicsoils,fre-quentlyforested,orsandysoilsalongwaterways;con-iferousforestation;andassociationswithrainfalland

othermoisture,andwaterwayswithchangingwaterlevels[4–10].InhighlyendemicnorthernWisconsin,excavationandcloseproximitytowaterwaysareriskfactorsfordiseaseacquisition[7,11].Outbreaks,andtherareenvironmentalisolationsofB.dermatitidis,haveprovidedsigni cantcluestotheecologyofthefungus.Theformerhaveimplicatedsuchecologicalsitesasriverbanks,abeaverpond,swampywood-lands,ruralagriculturalareas,andaprairiedogcolony[3,4,12].Severalofthesiteshaveincludedrot-tingwood,vegetation,andperhapsanimaldroppings.Therareenvironmentalisolationsoftheorganism,asreviewed[4,13],havealsopredominantlyincludedrottedwoodorvegetationandpresumablybirdoran-imaldroppings.Allbutoneisolationmicrofocihavebeeninornearsoil,andthesehaveincludedclayfromtheearthen oorofatobaccocuringbarn[14]andmaterialfromthe oorofapetroleum lteringshed[15].Theremainingisolationwasfromabagof