Midterm Subcut-sys-opportunistic

8/13/2019 Midterm Subcut-sys-opportunistic

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MYCOLOGY-VIROLOGY

MIDTERM LECTURE NOTES


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ENABLING OBJECTIVES: At the end of the period,

the students will be able to.

1. Discuss each medically important fungus as to:

Morphology and Physiology

methods of transmission

pathogenesis and clinical manifestations

methods of diagnosis

prevention and control

2. Perform slide preparation of fungal cultures3. Identify a fungus based on gross and microscopicappearance


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CONTENTS

Subcutaneous Mycoses

Sporothrix schenkii Loboa loboi

Agents of Chromomycosis Basidioboulus spp.

Agents of Mycetoma Conidiobolus spp.

Rhinosporidium seeberi

Systemic Mycoses

Histoplasma spp. Blastomyces dermatitidis

Cocciciodes immitis Paracoccidiodes braziliensis

Opportunistic Mycoses

Candida spp.


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SUBCUTANEOUS MYCOSES

Caused by exogenous fungi that normallyreside in nature, mostly in soil and vegetations

Portal of entry

Chronic infections

Sporotrichosis

Mycetoma

Chromoblastomycosis

Phaeohyphomycosis


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Sporotrichosis

Rose gardeners disease

Chronic infection of the subcutaneous tissues and

lymphatics

trauma (thorns or splinters) hand, arm or leg

Occupational hazard


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Sporotrichosis

Clinical manifestations

Fixed cutaneous sporotrichosis

Lymphocutaneous sporotrichosis

Pulmonary sporotrichosis

Osteoarticular sporotrichosis


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Sporotrichosis

Fixed cutaneous sporothricosis

Primary lesion begins as a small, non-healing

ulcer, commonly in the index finger or the

back of the hand

Lymphocutaneous sporotrichosis

nodular lesions

lymphatic vessels and lymph nodes draining the

region


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Sporotrichosis

Sporothrix schenckii

Dimorphic fungi

aspirated pus from nodules, swabs, scrapings,

biopsy tissue

Macroscopic

Rapidly growing, white,

pasty, moist colonythat later becomes

brown, black, wrinkled

or leathery

Microscopic

Mycelial form: narrow,

septate hyphae withpyriform conidia

arranged singly or in a

flowerette


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Mycetoma

Madura foot or Maduromycosis

Traumatic inoculation with several saprophytic

fungi

lower extremities but may occur in any part

of the body


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Mycetoma: Types

1. Actinomycotic

(bacterial)

Actinomycetes

Actinomyces Nocardia

Streptomyces


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MYCETOMA

2. Eumycotic (fungal)

Pseudallescheria boydii most common

Acremonium falciforme

Exophiala jeanselmei Curvularia

Madurella mycetomatis

Madurella grisea

Black grainmycetoma

Whitegrainmycetoma


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Pseudallescheria boydii

Ascomycota group

Soil, standing water and sewage

Clinical specimens: granules from the lesions Pseudoallescheriasis

Meningitis

Arthritis

Endocarditis

Brain abscess


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Pseudallescheria boydii

Macroscopic

Rapidly growing (5-10

days), initial growth as a

white fluffy colony

after several wks to

brownish-gray colony

Reverse tan to dark

brown

Microscopic

Asexual form :

Scedosporium apiospermum

golden brown elliptic,single-celled conidia borne

singly from the tips of

conidiophores

Sexual form : brown sac-like

cleistothecia containing asci

and ascospores


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Chromoblastomycosis(Chromomycosis)

Traumatic inoculation

Chronic infection producing warty or

cauliflower-like or tumor-like lesions mostly in

the lower extremities

Epidermis hyperplasia


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Chromoblastomycosis(Chromomycosis)

Etiologic agents

Cladosporium (Cladophialophora carrionii)

Phialophora (Phialophora verrucosa)

Fonsecaea (F. pedrosoi, F. compacta)

Rhinocladiella aquaspersa


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Chromoblastomycosis

Macroscopic All grow slowly and produce heaped-up and slightly folded,

darkly pigmented colonies with a gray to olive to black

velvety colonies; reverse side of colonies is jet black

Microscopic

Cladosporium: chains of budding blastoconidia borne from

branching conidiophores

Phialophora: short flask-shaped phialides with collarette Fonsecaea: conidial heads with sympodial arrangement of

conidia, primary conidia giving rise to secondary or tertiary

conidia


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Fonsecaea

F. pedrosoi

Polymorphic

1. Phialides

2. Chains of blastoconidia

3. sympodial

F. compacta

Spherical w/ broad base

connecting the conidia

Smaller and more

compact than pedrosoi


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Rhinocladiella

Produces lateral or terminal condia from

conidiogenous cell ( sympodial)

Conidia are elliptical to clavate


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Phaeohyphomycosis

Caused by dematiaceous fungi other than

those causing chromomycosis

Tissue morphology is mycelial

Subcutaneous and systemic infection


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Clinical manifestation

Subcutaneous phaeohyphomycosis

Cystic lesion, abscess

Paranasal sinus phaeohyphomycosis

sinusitis

Cerebral phaeohyphomycosis

Immunosuppressed


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PhaeohyphomycosisEtiologic Agents

Exophiala jeanselmei

Wangiella dermatitidis

Phialophora richardsiae Alternaria spp

Bipolaris spicifera

Curvularia spp

subQ: exophiala and wangiellaparanasal sinusitis ( allergic rhinitis or immunosuppression) : Bipolaris, Exserohilum, Curvularia andAlternaria


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Exophiala

Macroscopic

Grow slowly (7-21 days)and initially grows black

yeast-like colonies; as

colonies age they

become filamentous,

velvety, gray to black

Microscopic

Pale brownconidiophores that form

cylindrical annellids,

hyaline conidia gather at

its tip

Wangiella dermatitidis

Subcutaneous phaeohyphomycosis

cystic lesions occur most often in adults : subcutaneous phaeomycotic cyst


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Alternaria

Macroscopic

Grow rapidly and appear fluffy, gray to graybrown or gray green colonies

Microscopic Hyphae: septated and golden brown,

Conidiophores: simple sometimes branched whichbear a chain of large brown conidia resembling a

drumstick


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Curvularia

Macroscopic

Rapid growing, most are fluffy, gray to black

colonies

Microscopic

Hyphae are dematiaceous and septate

conidiophores are twisted at the ends where

conidia are attached

conidia are multicelled, curved with a central

swollen cell


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SYSTEMIC & OPPORTUNISTIC MYCOSES

Primary Systemic Mycoses

Coccidioidomycosis

Histoplasmosis

Blastomycosis

Paracoccidioidomycosis


Candidiasis, systemicCryptococcosis

Aspergillosis

Mucormycosis


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Primary Systemic Mycoses

Caused by dimorphic fungi

Dimorphic fungi

Yeast phase

When grown on enriched media usually supplementedwith blood at 35-37C

Is observed in vivo and is also known as the tissue orinvasive phase

Mycelial phase Observed on SDA at 25-30C

Saprophytic, observed in vitro


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Transmission

Inhalation of fungal spores

Lead initially to pulmonary infection which

may be symptomatic or asymptomatic

Dissemination to other body sites can occur


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Coccidioidomycosis

Acquired through inhalation of the infectivearthroconidia

Approximately 60% are asymptomatic and

self-limited respiratory tract infections Infection may become disseminated to

visceral organs, meninges, bone, skin, lymph

nodes and subcutaneous tissue


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Coccidioidomycosis

Etiologic agent: Coccidioides immitis

Clinical specimens: Sputum, tissues or body fluids

Direct microscopic examination from clinicalspecimens

Non-budding, thick-walled spherule, 20-200um in diameter containing either granular

material or numerous small non-buddingspores


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Coccidioides immitis

Macroscopic

Colonies appear after 3-21 days, delicate fluffy whitewhich turn tan or brown with age

Microscopic Mycelial phase: septate, branched hyphae that produce

thick-walled barrel-shaped, rectangular arthroconidia that

alternate with empty alternate cells

Yeast phase: large, round, thick-walled spherules withendospores observed in tissues and direct examination


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Coccidioides immitis

Other nonvirulent fungi that resemble C. immitis

microscopically may be found in the environment andmay produce hyphae that may dissociate into

arthroconidia

Considered as the most infectious of all fungi Extreme caution should be observed in handling

cultures of this organism

If culture plates are used, they should be handled

only in a biological safety cabinet

Cultures should be sealed in tape if the specimen is

suspected of containing C. immitis


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Safety Precautions in Handling

C. immitis Cultures

cotton-plugged tubes is discouraged andscrew-capped tubes are preferred

All microscopic preparations for examination

should be performed inside a BSC Cultures should be autoclaved as soon as the

final identification of C. immitis is made


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Histoplasmosis

A chronic granulomatous infection that is primary

and begins in the lungs, produce cavitary lesions

disseminate to the lymph node, liver, spleen, bone

marrow, kidneys, meninges Heart infxn in immunocompromised indls


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Histoplasmosis

inhalation of conidia or small hyphal

fragments

95% are asymptomatic and self-limited

most prevalent pulmonary mycosis of humans

and animals


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Histoplasma capsulatum

Direct microscopic examination

Difficult to visualize in the sputum and other

tissues

bone marrow smear: Wright or Giemsa-stained

Rarely in peripheral blood

Intracellular yeast in macrophages


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Histoplasma capsulatum

Macroscopic Slow growing

SDA:

white to brown mold

with fine fluffy texture

reverse side: white,

yellow or tan

BHI

moist, white to cream

heaped colony

Microscopic Mycelial phase:

septate hyphae with

large spherical or

pyriform tuberculatemacroconidia; some

produce small round

smooth microconidia


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Blastomycosis

Chronic suppurative and granulomatous

infection which involve the lungs and spread

to the long bones, soft tissue and skin

inhalation of the conidia and hyphal

fragments


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Blastomyces dermatitidis

Direct microscopic examination of tissues or body

fluids

large, spherical, thick-walled yeast cells 8-15 u usually with

a single bud that is connected to its parent cell by a broad

base

Mycelial phase: delicate, septate hyphae with round or

pyriform conidia borne singly on conidiophores resembling

lollipops


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Blastomyces dermatitidis

Macroscopic

Growth rate is 7-21 days

SDA: colony at first white, waxy, yeast-like and later

becoming cottony with white aerial mycelium; turnstan to brown with age

BHI with blood: cream to tan, waxy. Wrinkled colonies


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Paracoccidioidomycosis

Chronic granulomatous infection that begins

as a primary pulmonary infection

asymptomatic but may disseminate to

produce ulcerative lesions


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Paracoccidioides brasiliensis

Macroscopic:

SDA: white, glabrous, leathery colony which turns

tan-brown with age

BA: cream to tan, moist, wrinkled colony whichturns waxy with age

Microscopic

Mycelial phase small, septate, branched hyphae with intercalary

and terminal chlamydospores

few pyriform microconidia


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Paracoccidioides brasiliensis

Yeast phase

large, round to oval,

thick-walled yeast

cells (8-40 u) withmultiple buds with a

narrow base

mariners wheel


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Candidiasis

Most frequently encountered opportunistic

fungal infection

Etiologic agents

Candida albicans

C. tropicalis

C. parapsilosis

C. glabrata



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Candidiasis

are part of the normal flora, seen in the

oropharynx, GIT, GUT, skin

Infections are believed to be endogenous in

origin or nosocomial


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Candida Infections In Normal And

Immunocompromised Hosts

Intertriginous candidiasis (skin folds)

Onychomychosis and paronychia

Perleche

Oral thrush

Vulvovaginitis

Pulmonary infection

Eye infections

Endocarditis

Meningitis


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Predisposing Factors For Candidiasis

Alteration in the normal skin and mucous

membrane barriers

Prolonged antibiotic administration

Use of immunosuppressive drugs

Diseases of the immune system


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Candida

Direct microscopic examination of clinicalspecimens

Budding yeast cells

Pseudohyphae

Definitely identified microscopically by production of

germ tubes and chlamydospores


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Germ Tube Test

A hypha-like extension of the yeast cells with

no constriction at the point of origin

Candida albicans will form germ tubes when

incubated with serum at 37C for a few hours


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Cornmeal Agar with Tween 80

Conidiation

ID of Candida spp and other yeasts through

examination of

hyphae, blastoconidia, chlamydospores. and

arthroconidia

Tween 80

reduce the surface tension

to allow conidiation

C l A ith T 80


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Cornmeal Agar with Tween 80Procedure

colony from the 1 culture media

Inoculate a plate of CMA with 1% T80 and trypanblue by making 3 parallel cuts about inch apart at a45 angle to the culture medium

RT for 48 hours

After 48 hours, remove and examine the areas where

cuts into the agar were made

Commonly encountered yeast in CMA-T80 Agar


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Commonly encountered yeast in CMA T80 Agar

Organism Arthro-

conidia

Blastoconidia Pseudohyphae or

Hyphae

C. albicans

-

Spherical clusters at

regular intervals on

pseudohyphae

Chlamydoconidia

on hyphae

C. glabrata-

Small, spherical, tightlycompact

None

C. krusei

-

Elongated, clusterered

at septae of

pseudohyphae

Branched

pseudohyphae

C. parapsilosis

-

Present but not

characteristic

Sagebrush like,

Giant hyphae

Commonly encountered yeast in CMA-T80 Agar


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Organism Arthro- conidia Blastoconidia Pseudohyphae or

Hyphae

C. kefyr

(pseudotropicalis)- Elongated, parallel to

pseudohyphae

PH present, not

characteristic

C. tropicalis - Randomly appear on PH

& H

PH present, not

characteristic

-

C. neoformans - Round to oval separated

by capsule

Rare, usually not

seen

Saccharomyces - Large and spherical Rudimentary H

sometimes present

Trichosporon Numerous,

resemble

Geotrichum

Maybe present but

difficult to find

Septated hyphae is

present


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Cryptococcosis

An acute, subacute or chronic fungal infectionthat has several manifestations

Disseminated disease

with or without meningitis in immunocompromisedpatients

Meningitis occur 2/3 of patients

very common in patients with AIDS


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Cryptococcus neoformans

Saprophyte

pigeon, bat, or bird droppings, decaying

vegetations, fruit, plants

Inhalation

lungs then disseminate to meninges and other

sites


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Cryptococcus neoformans

Direct microscopic

examination

Spherical, single or multiple

budding, thick-walled yeast

cell (2 to 15 um)

surrounded by a wide,

refractile polysaccharide

capsule

Macroscopic Colonies appear in 1-5

days

smooth, white to tan,

mucoid, gelatin-likecolonies (soap-bubble)

Brown-black colonies

on Niger seed agar

O i C l G Bl t A th Chl


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Organism Capsule Germ

Tube

Blasto-

conidia

Arthro-

conidia

Chlamy-

dospore

C. albicans - + + - +

C. tropicalis - - + - V

C. parapsilosis - - + - -

C. glabrata - - + - -

C. neoformans + - + - -

Geotrichum - - - + -

T. beigilii - - + + -


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Organism FERMENTATION Urease Nitrate

Reduction

G M S L

C. albicans + + - - - -

C. tropicalis + + + - - -

C. parapsilosis + - - - - -

C. glabrata + - - - - -

C. neoformans - - - - + -

Geotrichum - - - - - -

T. beigilii - - - - + -

Aspergillosis


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Aspergillosis

disseminated infection in IC patients

Other infection

invasive lung infection

Pulmonary or sinus fungus ball (tangled mass of hyphae)

Mycotic keratitis

allergic pulmonary aspergillosis

External otomycosis

Onychomycosis

Sinusitis, endocarditis, CNS infxn

inhalation


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Aspergillus fumigatus

Direct microscopic examination

Septate hyphae that usually show dichotomous

branching (45 angle branching)

Macroscopic Rapidly growing mold (2-6 days)

fluffy to granular, white to blue green colonies

Microscopic Branching septate hyphae that terminate in

conidiophore

MOST COMMONLY RECOVERED SPP FROM IC PATIENTA. FLAVUS SOMETIMES RECOVEREDBotany repeated branching into two equal parts.Methenamine silver stained tissue section showing dichotomously branched, septate hyphae.



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expands into a largeDOME-SHAPED vesicle

with BOTTLE-SHAPED

phialides from which

chains of conidia arise


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Zygomycosis (Mucormycosis)

Decaying vegetable matter, old bread or in soil

Acquired by inhalation

Less common cause of infection as compared to

Aspergillus Rhinocerebral infection involving nasal mucosa,

palate, sinuses and brain

Perineural invasion

Retro-orbital spread (brain)

Lungs, GIT


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Zygomycetes

Direct microscopic examination of tissue

specimens or exudates

Branching non-septate hyphae

Macroscopic

Fluffy, white to gray to brown colonies covering

the surface of the agar within 24-95 hours, grayish

hyphae with brown to black sporangia


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Zygomycetes

Microscopic large ribbon-like hyphae

irregular in diameter

non-septate

Sporangia

Sac-like sporangiospores at the tip of sporangiophore

Stolons

Connects sporangiphore

Rhizoids are attached


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Mucor

Sporangiophores the tip

of which have sporangia

filled with

sporangiospores No rhizoids and stolons


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Rhizopus

unbranched

sporangiophores with

rhizoids that appear at

the point at which thestolon arises


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Penicillium

When clinically

significant, clinical

manifestations include

bronchopulmonary,

endocarditis, cutaneous

ulcers of extremities


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Fusarium

Infections becoming more common esp in IC patients

(Hyalohyphomycosis)

Common environmental flora

mycotic keratitis after traumatic implantation into the cornea

Other infections: sinusitis, wound (burn) infections, allergic

fungal sinusitis, respiratory tract secretions
http://www.mycology.adelaide.edu.au/Mycoses/Opportunistic/Hyalohyphomycosis/index.htmlhttp://www.mycology.adelaide.edu.au/Mycoses/Opportunistic/Hyalohyphomycosis/index.html


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Pneumocystis jiroveci (carinii)

Opportunistic atypical fungus causing

pneumonia in immunocompromised hosts

Ideal specimen broncho-alveolar lavage fluid

or lung biopsy

Does not grow in routine culture methods


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Polyene macrolide antifungals


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Agent Source Function Treatment for

Amphotericin B

(liposomal prep)

Streptomyces

nodosus

Binds ergosterol and

alter selectivepermeability

IV:Aspergilossis

Candida spp.Cryptococcus

Zygomycetes

R: P.boydii,

A. terreus,

Trischosporon,Fusarium

Nystatin S. noursei Not absorbed by GIT,

not given

parenterally (TOXIC)

Oral or

vulvovaginal

candidiasis

Griseofulvin Penicillium Binds microtubular

protein (mitosis)

Oral tx:

dermatophytes

non responsive to

azole

Antimetabolite


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Antimetabolite

5- Fluorocytosine (Flucytosine)

5-fluorouracil

incorporated to fungal RNA and inhibit protein

synthesis

Fluorodeoxyuridine monophosphate

Inhibitor of DNA synthesis

Combination therapy w/ AmB

Candida spp. and C. neoformans

Side effect & resistance when used alone

Azole antifungal drugs


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Agent Application Treatment Adverse rxn

Clotrimazole &

Miconazole

Topical or

intravaginal

Mild dermatophytosis

(T.versicolor)

Burning, itching,

skin irritation

Fluconazole Oral or IV Candida and Cryptococcus

(CNS)

S or R (C. glabrata)

R: C.krusei &

Rhodotorula spp)

Ketoconazole Topical or

oral

Mild

ParacoccidioidomycosisBla

stomyces & Histoplasmosis

Chronic mucocutaneous

candidiasisP. boydii

Elevated liver

enzymes, nausea,

dose related-

gynecomastia;

Decreased libido;oligospermia

A l if l d


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Azole antifungal drugs

Agent Application Treatment Adverse rxnItraconazole Expanded

activity w/

ketoconazole

Aspergillosis

Sporothricosis

Cryptococcosis

OnchymycosisBlastomycosis

GIT & vestibular

disturbances,

edema, skin

irritation

Voriconazole

(new triazole)

Expanded

activity

compared

w/itraconazole

Fusarium

C.krusei & C.

glabrata

R: Zygomycetes;

Elev.liver

enzymes; visual

disturbances

E hi di


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Echinocandins

Agent Application Treatment Adverse rxnCaspofungin

Micafungin

Anidulafungin

Fungicidal

Fungistatic

Candida spp

(krusei,glabrata)

Aspergillus

R:

C.neoformans

Trichosporon,

RhodotorulaZygomycetes

Selenium

sulfide

Shampoo

Sporicidal

Malasezzia furfur

T. tonsurans

Potassium

iodide

oral Cutaneous/lymp

hatic

sporothricosis

Bitter taste,

allergic rash

and anorexia

Documents

Midterm Subcut-sys-opportunistic