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8/18/2019 Agents of Systemic Mycoses
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Micro-2|Midterm
Agents of Systemic Mycoses
Dissemination of any fungal agent, yeast, orbacteria-like fungus to involve any tissue ororgan. Agent must be dimorphic.
• Histoplasma capsulatum
• Coccidioides immitis
• Paracoccidioides brasiliensis
• Blastomyces dermatitidis
Histoplasma capsulatum
• Histoplasmosis
o an infection of thereticuloendothelial system resultingin patchy bronchopneumoniacontaining yeast-ladenphagocytic cells within alveolarspaces.
o aka Reticuloendothelialcytomycosis, Cave dse,Spelunker’s dse, Darling dse
• orldwide in distribution
o it is endemic in the Mississippi,Missouri, !t. "awrence, and #hio$iver %alleys
• !trong association with ird and atdroppings!
• &eleomorph' Emmonsiella capsulata
• &his organism resides in soil "ith highnitrogen content.
• H.capsulatum var! duboisii , endemic in(entral Africa, causes disease involvingthe skin and ones!
• H.capsulatum var! farciminosum,causes epi)ootic lymphangitis in horsesand mules.
Heterothallic # re*uires 2 mating strainsto produce se+ual forms.
Macroscopic Morphology$ o slow growtho white to dark tan with ageo woolly, cottony, or granular
Microscopic Morphology$
o Microconidia- $ound to pyriformo Macroconidia # large echinulate
or tuberculate
%east form$ !mall, oval yeast in
histiocytes, phagocyteso resemble C.glabrata;
dierentiated by &uorescenttechni'ues or culture.
(herapy$ tracona)ole, Amphotericin
Coccidioides immitis
• Coccidioidomycosis
o usually an asymptomatic or mildlysymptomatic self-limiting upper$&, but may become disseminatedand fatal.
• San )oa'uin *ever or +alley *ever
o it is endemic in southwestern /!,esp. Ari)ona and (alifornia.
• (aution must be taken with cultures0o organism produces arthroconidia
which are very easily inhaled.• 1robably the most virulent of all human
mycotic agents.• Allergic manifestations' to+ic
erythema, erythema nodosumdesertbumps3, erythema multiforme valleyfever3, and arthritisdesert rheumatism3
• !oil-dwelling mold0
• rimary dse usually resolves w4o therapyand confers a strong speci5c immunity toreinfection.
• Secondary coccidioidomycosis, whichcan include nodules, cavitary lung dse,and4or progressive pulmonary dse.
• *ilipinos and lacks run the highest riskof dissemination w4 meningeal
involvement.• $eside in a narrow ecologic niche known
as the o"er Sonoran life .one,characteri)ed by rainfall and semiaridconditions.
• C.immitis – !an 6oa*uin %alley region of(alifornia
• C.posadasii 7 found in the desert ofsouthwest of the /!, Me+ico and!.America.
• Macroscopic Morphology$
o $apid growtho white to tan to dark gray
o %oung colonies tenaciouso /ld colonies cottonyo &end to grow in concentric rings
• Microscopic Morphology$
o Alternating one-celled, arrel-shaped arthroconidia w4 dis8unctorcells
• %east form$ !pherules containingendospores
• rogressive cleavage 7 production ofendospores by rupture of the spherulewall, w4c releases endospores into thebloodstream and surrounding tissue.
• Microscopic e0amination of culture$
fertile hyphae arising at right angles to thevegetative hyphae, producing alternatinghyaline arthoconidia.
• (herapy$ 9lucona)ole, Amphotericin
Paracoccidioides brasiliensis
• aracoccidioidomycosis
o aka South Americanlastomycosis, 1ra.ilianlastomycosis, ut.-Splendore-
8/18/2019 Agents of Systemic Mycoses
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Micro-2|MidtermAlmeida dse, aracoccidioidalgranuloma
o a chronic, progressive fungal dseendemic to central and southAmerica.
• 1.brasiliensis is pulmonary, and infection isusually unapparent and asymptomatic,subse*uent dissemination leads to
formation of ulcerative granulomatouslesions of the buccal, nasal and :mucosa.
• Macroscopic morphology$
o slow growtho white to beigeo colony glabrous, folded or velvety
• Microscopic morphology$
o typical budding yeast withmultipolar budding at theperiphery, resembling a mariner’s"heel.
o daughter cells are connected by anarro" ase.
o many buds of various si)es canoccur, or there may be only a fewbuds giving the mickey mousecap to the yeast cell.
• %east form$ Multiple blastoconidia,budding from single, large yeast
Blastomyces dermatitidis
• 1lastomycosis
o most prevalent in middle-agedmen, as are other systemicmycoses, presumably because ofmen;s greater occupational andrecreational e+posure to the soil.
o rimary infection #
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Micro-2|Midterm• presents as Rhinocereral .ygomycosis
o in the sinuses where conidia areinhaled and take up residence
o from the sinuses, infection rapidlyspreads to the orbits, face, palate,and brain.
Cunninghamella
recovered from the sinuses or other
organs from disseminated dse. isolate is common in the environment
rapidly growing ?ygomycetes that form acottony colony that is initially white butbecomes gray with age.
Mucor
Rhinocereral .ygomycosis
commonly isolated from the environmentworldwide
sporangiospores are formed insporangia on erect sporangiophores
rapidly growing ?ygomycetes that form
cottony, dirty white colonies that becomemousy-brown to gray with age.
Rhi.opus
most common )ygomycete that causeshuman disease
classically involved in diaetic patients"ith ketoacidosis, presenting asrhinocereral .ygomycosis
$hi)opus sp. is e+tremely refractory totreatment
@rect sporangiophores terminated bydark sporangia and sporangiospores.
Syncephalastrum
rarely implicated in human dse, but hasben documented in cutaneous infections.
sometimes confused w4 Aspergillus oninitial e+amination
colonies are initially white and becomegray with age.
o growth rate is rapid, as with other)ygomycetes, with coloniescovering the entire surface of theagar.
S6(A(6 7 H%A846 SAR/H%(6S
Aspergillus
Allergic ronchopulmonary
aspergillosis2asthma, allergies growing in mucous plugs in the lungs butdo not penetrate the lung tissue3
*ungus all$ free in preformed lungcavities surgical removal to reducecoughing, w4c may induce pulmonaryhemorrhage3
nvasive aspergillosis4severe neutropenia,chronic granulomatous dse, cystic 5brosis,burns
o invades tissues causing infarctsand hemorrhage
o 4asal coloni.ation #
pneumonia4meningitiso Cellulitis in burn patients may
also disseminate1eauveria
a rare human isolate, uncommonlyassociated w4 keratitis
a known insect pathogen and is foundworldwide on vegetation and in the soil
Abundant, single-celled, tear-shapedsympoduloconidia are formed onsympodulae, w4c taper e+tremely from arather swollen base.
Chrysosporium
rare cause of disease
have been recovered from nails and skinlesions
found in the environment worldwide
simple, wide-based, single-celled conidiaare produced on nonspeciali)ed cells.
*usarium
fre*uently seen in mycotic keratitis softcontact lenses wearer and of contact lenssolution3
1one marro" transplant patients,mortality from infections caused by thefusaria approaches 9::;
are easily recovered in lood culturesystems
S6(A(6 7 D6MA(8AC6/
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Micro-2|Midtermsystem dse patients have beenidenti5ed as % drug users3
found in the environment and have apredilection for cellulose products
o they have been known todevastate printed literature andlirary holdings and have beenassociated with indoor air 'uality
prolemsCladosporium
an infre*uent cause of disease,(ladosporium sp. are primarily recoveredas aoratory contaminants
infections are typically con5ned to thesinuses or following traumatic inoculation
ubi*uitous in nature, this isolate can berecovered from nearly any location in theworld.
Curvularia
most often implicated in chronicsinusitis in immunocompetent patients
this fungus is fre*uently recovered fromgrass, leaves, and decayingvegetations
multicelled conidia are produced onsympodial conidiophore
Agents of %east 8nfections
&hese are caused by fungi that usually do notinduce dse and occur almost e+clusively inimmunocompromised patients who are oftenon treatment with corticosteroids, cytoto0icdrugs, or other immunosuppressive drugs.
• (andidiasis
• (ryptococcus &orulosis, @uropeanblastomycosis3
• $hodotorula
• 1neumocystis
Candida albicans
• east endogenous to our mucousmemrane normal &ora
• form germ tues at =>?C in serum
• form pseudohyphae and true hyphae when it invades tissues nonpathogenic(andida do not3
•Diseases2redisposing conditions$
o erleche # crevices ofmouth4malnutrition
o #ral thrusho @sophagitiso !epticemiao @ndocarditiso (utaneous infectionso east vaginitiso (hronic mucocutaneous candidiasis
• Diagnosis$
o @/H$ pseudohyphae, true hyphae,budding yeasts
o Septicemia$ culture labidenti5cation' biochemicaltests4formation of germ tues
• (reatment$
o &opical imida)oles or oralimida)oles0 nystatin
o Disseminated$ Amphotericin or9lucona)ole
Cryptococcus neoformans
6ncapsulated yeast Monomorphic3
(eleomorph$ Filobasidiella neoformans
6nvironmental source$ !oil enrichedwith pigeon droppings
Diseases2redisposing conditions$
o Meningitis4Bodgkin;s, AD! thedominant meningitis3
o Acute pulmonary usuallyasymptomatic34pigeon breeders
Diagnosis of Meningitis$ CS*o detect capsular Ag in (!9 by
"ate+ agglutination or counterimmunoelectrophoresis3
o 8ndia ink mount misses C>3 of(!9 sediment to 5nd buddingyeasts with capsular halosB
(ultures urease positive yeast3
(reatment$ AM E C9( until afebrile andculture negative, then
8/18/2019 Agents of Systemic Mycoses
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Micro-2|Midtermo -ray$ patchy in5ltrative ground
glass appearance3, the lowerlobe periphery may be spared.
C/6C(8/4, (RA4S/R(, A4D C-2>0 breaks down keratin andskin layers to see fungi present moreeasily0 skin, hair, nails, and tissue
! Calco&uor Jhite # binds topolysaccharides present in chitin of thefungus or to cellulose0