Medical Microbiology

WesternEuropeisfreeofthedisease.Thepathogenisnotcommunicable

amonghumans.Nospecialprophylacticmeasuresaretaken.

Coccidioidesimmitis(Coccidioidomycosis)

Morphologyandculture.C.immitisisanatypicaldimorphicfungus.Incul-

tures,thisfungusalwaysgrowsinthemycelialform;inbodytissues,how-

ever,itneitherbudsnorproducesmycelia.Whatisfoundinvivoarespherical

structures(spherules)withthickwallsandadiameterof 15 – 60 lm,each

filledwithupto 100 spherical-to-ovalendospores.

C.immitisisreadilycultivatedontheusualfungusnutrientmediums.

Afterfivedaysofincubation,awhite,wooly(fuzzy)mycelialcolonyisob-

served.Oneofthemorphologicalcharacteristicsofthemyceliumistheasex-

ualarthrosporesseenasseparateentitiesamongthehyphae.

Pathogenesisandclinicalpicture.Theinfectionresultsfrominhalationof

dustcontainingarthrospores.Primarycoccidioidomycosisisalwayslocalized

inthelungs,wherebythelevelofmanifestationvariesfromsilentinfections

(60%ofinfectedpersons)toseverepneumonia.Fivepercentofthoseinfected

developachroniccavernouslungcondition.Infewerthan 1 %,hematogenous

disseminationproducesgranulomatouslesionsinskin,bones,joints,andme-

ninges.

Diagnosis.Theavailabletoolsarepathogendetectioninsputum,pus,cere-

brospinalfluidorbiopsies,andantibodyidentification.Thespherulescanbe

seenunderthemicroscopeinfreshmaterial.Thefunguscanbereadilycul-

turedonSabouraudagarat 258 C.Theresultingarthrosporesarehighlyin-

fectiousandmustbehandledverycarefully.Antibodiescanbedetectedusing

thecomplementfixationtest,gelprecipitationorlatexagglutination.Acoc-

cidioidinskintestmeasuringanycellularallergytocomponentsofthefungus

isusedasaninitialorientationtestifaninfectionissuspected.

Therapy.AmphotericinBcanbeusedtotreatthedisseminatedforms.Anoral

azolederivativewillserveasanalternative,orforuse,inclinicallylesssevere

forms.

Epidemiologyandprevention.Coccidioidomycosisisendemictodesert

areasofCalifornia,Arizona,Texas,NewMexico,andUtahandisonlyrarely

observedelsewhere.Thesourceofinfectionisthefungus-richsoil.Animals

canalsobeinfected.Thisdiseaseisnottransmittedamonghumansorfrom

animalstohumans.

360 6 FungiasHumanPathogens

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Kayser, Medical Microbiology © 2005 Thieme