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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-

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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

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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