clinicalandtherapeuticterms,theyarethesameascandidiasis.Malassezia
furfuroccasionallycausescathetersepsisinprematureneonatesandpersons
whohavetobefedlipidsparenterally.Lipidsencouragegrowthofthisyeast.
Penicilliosis.ThisfungalinfectioniscausedbythedimorphicfungusPenicil-
liummarneffei,whichprobablyinhabitsthesoil.P.marneffeiinfectionsare
oneofthemostopportunisticinfectionsmostfrequentlyseeninAIDSpa-
tientswhoeitherliveinSoutheastAsiaorhavestayedinthatareaforawhile.
Theinfectionfociarelocatedprimarilyinthelungs,fromwheredissemina-
tiontootherorganscantakeplace.Thetherapeuticofchoiceintheacute
phaseisamphotericinB,thistreatmentmustbefollowedbylong-termpro-
phylacticazoles(itraconazole)topreventremission.Pneumocystiscarinii(Pneumocystosis)
&Pneumocystiscariniiisasingle-celled,eukaryoticmicroorganismthatwas
originallyclassifiedasaprotozoan,butisnowconsideredafungus.This
pathogencancausepneumoniainpersonswithdefectivecellularimmune
systems,inparticularthoseshowingAIDS.Extrapulmonarymanifestations
arealsorecordedinasmallnumberofcases.Laboratorydiagnosticmethods
includedirectdetectionofthemicrobesunderthemicroscope,bymeansof
directimmunofluorescenceorPCR.Appropriateanti-infectiveagentsfor
therapy includecotrimoxazole, pentamidine, or a combination ofthe
two. &Pneumocystiscariniiisasingle-celled,eukaryoticmicroorganismthatwas,
untilrecently,classifiedwiththeprotozoans.MolecularDNAanalysishasre-
vealedthatitresemblesfungimorethanitdoesprotozoans,althoughsomeof
thecharacteristicpropertiesoffungi,suchasmembraneergosterol,aremiss-
inginPneumocystiscarinii.Thismicrobeoccursinthelungsofmanymam-
malianspeciesincludinghumanswithoutcausingdiseaseinthecarriers.
Clinicallymanifestinfectionsemergeinthepresenceofsevereunderlying
defectsincellularimmunity,asinAIDS.
Morphologyanddevelopmentalcycle.Threedevelopmentalstagesare
knownforP.carinii.Thetrophozoitesareellipticalcellswithadiameter
of 1 .5– 5 lm.Presumably,thetrophicformreproducesbymeansofbinary
transversefission,i.e.,asexually.Sexualreproductiondoesnotbeginuntil
twohaploidtrophozoitesfusetomakeonediploidsporozoite(orprecyst),
whichareconsideredtobeanintermediatestageinsexualreproduction.
Afterfurthernucleardivisions,thesporozoitespossesseightnucleiatthe
endoftheirdevelopment.Thenucleithencompartmentalizetoformeight
sporeswithadiameterof 1 – 2 lmeach,resultinginthethirdstageofdevel-370 6 FungiasHumanPathogens6
Kayser, Medical Microbiology © 2005 Thieme