Medical Microbiology

352 5 GeneralMycology

sexualspores:zygospores,ascospores,andbasidiospores.Sexualsporesare

onlyrarelyproducedinthetypesoffungithatparasitizehumantissues.

Sexualreproductionstructuresareeitherunknownornotpresentin

manyspeciesofpathogenicfungi,knownasfungiimperfecti(deuteromy-

cetes).

GeneralAspectsofFungalDisease

&Besidesfungalallergies(e.g.,extrinsicallergicalveolitis)andmycotoxi-

coses(aflatoxicosis),fungalinfectionsarebyfarthemostfrequentfungaldis-

eases.Mycosesareclassifiedclinicallyasfollows:

— Primarymycoses(coccidioidomycosis,histoplasmosis,blastomycoses).

— Opportunisticmycoses(surfaceanddeepyeastmycoses,aspergillosis,

mucormycoses, phaeohyphomycoses, hyalohyphomycoses, cryptococ-

coses;penicilliosis,pneumocystosis).

— Subcutaneousmycoses(sporotrichosis,chromoblastomycosis,Madura

foot(mycetoma).

— Cutaneousmycoses(pityriasisversicolor,dermatomycoses).

Littleisknownaboutfungalpathogenicityfactors.Thenaturalresistanceof

themacroorganismtofungalinfectionisbasedmainlyoneffectivephagocy-

tosiswhereasspecificresistanceisgenerallythroughcellularimmunity.Op-

portunisticmycosesdevelopmainlyinpatientswithimmunedeficiencies

(e.g.,inneutropenia).Laboratorydiagnosticmethodsforfungalinfections

mostlyincludemicroscopyandculturing,inordertodetectthepathogens

directly,andidentificationofspecificantibodies.Therapeuticsfortreatment

ofmycosesincludepolyenes(aboveallamphotericinB),azoles(e.g.,itraco-

nazole,fluconazole,voriconazole),allylamines,antimetabolites(e.g.,5-flu-

orocytosine),andechinocandins(e.g.,caspofungin).Antimycoticsareoften

administeredincombination. &

FungalAllergiesandFungalToxicoses

MycogenicAllergies

Thesporesofubiquitousfungicontinuouslyentertherespiratorytractwith

inspiratedair.Thesesporescontainpotentallergenstowhichsusceptiblein-

dividualsmaymanifeststronghypersensitivityreactions.Dependingonthe

localizationofthereaction,itmayassumetheformofallergicrhinitis,bron-

5

Kayser, Medical Microbiology © 2005 Thieme