Mycology Review

MYCOLOGY REVIEW

Fungi vs. Bacteria:

Criteria Bacteria Fungi

Yeast Mold

Size 3 microns 3 microns at least

(like bacteria)

3 feet

Cellular differentiation Unicellular Unicellular Multicellular

Nuclear & cell

structure Prokaryotic Eukaryotic

Chemical Composition

Cell Wall

Cell Membrane

Peptidoglycan

(-) Sterols (except

Mycoplasma)

Chitin, Glucan & Mannans

(+) Sterols – “Ergosterols”

Reproduction Asexual (Binary Fission) Asexual (B.F.) and Sexual

Spore For Adverse conditions

Thermoresistant

For Reproduction

Not Thermoresistant

Life Cycle Simple Simple complex

Morphology:

Dimorphism – the ability to exist as two morphologic forms

Thermally dimorphic – dimorphism is induced by change in temperature

YEASTS/SPIRULES MOLDS

Body Temp. Room Temp.

Animal Habitat Natural Habitat

Parasitic Saprobic

Facultative anaerobes Aerobes

Reproduce via

Budding or

Sporulation

Sporulation

Yeast phase Hyphal/Mycelial phase

Exist at conditions:

↑ Temp

↓ O2

↓ Nutrients

↓ Temp

↑ O2

↑ Nutrients

Hyphae of mold can be classified:

1. Septate/Non-septate

a. Septate – with crosswalls; unicellular per septation; can still reproduce when it breaks

b. Non-septate – coenocytic/aseptate; continuous; multicellular; cannot survive when it breaks

2. Reproductive/Vegetative

a. Reproductive – aerial; sprout from vegetative hyphae vertically; produce sexual spores

b. Vegetative - anchors fungus to substrate; absorbs nutrients and water

3. Hyaline/Dematiaceous

a. Hyaline – non-pigmented

b. Dematiaceous – pigmented (black-brown)

Tissue forms: what we see in histopathologic examination (so, kapag may microscope sa prax, ito lang ang madalas na nasa pointer)

YEAST CELLS Organism Disease Type of Mycoses

Intracellular Histoplasmosis capsulatum Histoplasmosis Endemic Respiratory

Broad-based Blastomyces dermatitidis Blastomycosis Endemic Respiratory

Multiple buds (like a mariner’s

wheel)

Paracoccidioides braziliensis Paracoccidioidomycosis Endemic Respiratory

Encapsulated Cryptococcus neoformans

Cryptococcus gatti

Cryptococcosis Opportunistic

With Transverse septum Penicillium marneffei Penicilliosis marneffei Endemic Respiratory

Cigar-shaped Sporothrix schenckii Sporotrichosis Subcutaneous

HYPHAE

Coenocytic Zygomycetes Zygomycosis Opportunistic

Dichotomously branched Aspergillus spp.

A.fumigatus (most common)

Aspergillosis Opportunistic

Hyaline, septate Dermatophytes Dermatophytosis Cutaneous

Demetiaceous, septate Several dematiaceous fungi

Phaeoanneliomyces wernekii

Phaeohyphomycosis

Tinea nigra

Subcutaneous

Superficial

YEAST CELLS &PSEUDOHYPHAE Candida spp.

C. albicans (most common)

Candidiasis Opportunistic

GRANULES Several dematiaceous and non-

dematiaceous fungi

Mycetoma Subcutaneous

SPHERULES Coccidiodes immitis Coccidioidomycosis Endemic Respiratory

FISSION/SCLEROTIC BODIES Several dematiaceous fungi Chromomycosis Subcutaneous

The next part is a compilation of all the diseases we tackled in our mycology module. Dr.Padla said that our prax will include the laboratory

diagnosis-part of our lectures.

Capsule:

Some fungi have

capsules.

Cryptococcus

neiformans – the

only pathogenic

yeast which has a

capsule

Thermally dimorphic fungi in our

mycology module:

- Sporothrix schenckii

- Histolasma capsulatum

- Blastomyces dermatidis

- Coccidioides immitis

- Paracoccidioides braziliensis

- Penicillium marneffei

2

I. SUPERFICIAL MYCOSES

limited to the stratum corneum, the dead layer of the skin

affect only nonliving tissues

also called “tineas” (larva, worm)

infections are usually cosmetic problems, easily diagnosed and treated

Ptyriasis versicolor

Etiology: caused by Malassezia furfur,

Tissue form: short hyphae and clusters of yeast-like cells

Infectious form: short hyphae and clusters of yeast-like cells

Laboratory Diagnosis:

o KOH examination: skin scrapings

o Spaghetti and meatball appearance (short hyphae and clusters of yeast-like cells)

o Wood’s lamp: lesions fluoresce golden yellow

o Cannot be cultured unless olive oil and fatty acids are incorporated

Tinea Nigra

Etiology: caused by Phaeoanneliomyces wernekii

Tissue form: dematiacious hyphae

Infectious form: dematiacious hyphae

Laboratory Diagnosis: direct microscopic exam’n:

KOH treated skin scrapings: pigmented budding cells, budding fragments, blanching hyphae

Piedra

Black Piedra White piedra

Etiology:

Piedra hortae

Hair shaft: perfect (teleomorphic) state

spindle-shaped ascospores w/in

asci develop

Culture: asexual (anamorphic) state

slow growing brown to reddish

hyphae with many

chlamydoconidium-like cells

Trichosporon beigelii

yeast-like, hyphae that fragmnet into

arthroconidia

Laboratory

Diagnosis

KOH: (crushed nodules)

- asci containing fusiform ascospores with

whiplike extensions

Direct KOH: septate hyphae that fragment into

arthroconidia wc rapidly round up

Blastoconidia may be present along hyphae

Confirmed by culture

II. CUTANEOUS MYCOSES

a.k.a. Dermatophytoses; normally called “tinea” and more commonly “ringworms”

result of the host reaction to the enzymes released by the fungus during its digestive process

involve infections that extent into the (epidermis/outer keratinized layer SKIN, HAIR, and NAILS

Living tissue not invaded; systemic spread is rare

Most common human mycoses

CAUSE: Dermatophytes

o “keratinophilic fungi”; able to utilize keratin as nitrogen source

o Dermatophytes classified according to:

Ecological niche or habitat:

1. Anthropophilic – exclusively in association with humans

2. Zoophilic – found in association with domesticated and wild animals and birds

3. Geophilic – species frequently isolated from the soil

3 Genera:

These genera, in the anamorphic (asexual) state, are classified according to sporulation patterns,

morphologic features and nutritional requirements:

1. Trichophyton – infects skin, hair and nails (tip: three=Tri)

2. Microsporum – infects skin and hair (tip: MSH)

3. Epidermophyton (E. flocossum)– infect skin and nail (tip: ESN)

Trichophyton Microsporum Epidermophyton

1. T. rubrum 1. M. cruisis 1. E. floccosum

3

2. T. mentagrophytes 2. M. gypseum

3. T. verrucosum 3. M. audoinii

4. T. tonsurans 4. M. ferrugineum

5. T. suodanese 5. M. canis

6. T. violaceum

7. T. schoenleinii

8. T. concentricum

GENERAL CHARACTERISTIC OF THREE GENERA:

GENUS MACROCONIDIA MICROCONIDIA

Trichophyton Usually rare, smooth, pencil-

shaped, thin-walled, normally

contain 3-8 cells

Few to numerous, round or

oval, borne singly or in grape-

like clusters

Microsporum Numerous, rough, spindle-

shaped, echinulate, thick-

walled, singly, usually contains

3-7 cells

Few club-shaped, borne singly,

usually present

Epidermophyton Numerous, smooth-walled,

club-shaped, formed singly, in

pairs or clusters, contain 2-4

cells in groups

Absent

TRICHOPHYTONS

SPECIES MACROCONIDIA MICROCONIDIA

T. rubrum Variable number Oval shape, periform, singly

along hyphae

T. mentagrophytes Not always present Numerous, borne in clusters

T. verrucosum Absent Absent

T. tonsurans Rare and irregular form Numerous, tear/club shape

T. suodanese Absent Tear shape along hyphae

T. violaceum Rare/Absent Rare/Absent

T. schoenleinii Absent Rare

T. concentricum Absent/Rare Absent/Rare; balloon shape

MICROSPORUMS


M. cruisis Numerous, long, rough knob

like ends, spiky, with many

cells

M. gypseum Numerous, symmetric, with

round ends, smooth walled

M. audoinii Distorted if present

M. ferrugineum Rare, resemble those of M.

canis

M. canis Smooth edge, round ends,

knob-like

EPIDERMOPHYTON


E. floccosum Smooth, club-shaped with

rounded ends, numerous

Absent

Trichophyton Microsporum Epidermophyton

Infects: skin, hair & nails Infects: skin & hair Infects: skin & nails

Transmission:

Human to human

Animal to human

Transmission:

Human to human

Animal to human

Soil to human

Transmission:

Human to human

TISSUE FORMS AND INFECTIOUS PARTICLES:

o hyaline septate hyphae

SELECTIVE MEDIUM USED:

o Mycobiotic Agar containing Cyclohexamide (inhibits saprophytic fungi growth) Chloramphenicol and Gentamycin (inhibits

bacterial growth to prevent contamination)

LABORATORY DIAGNOSIS:

o KOH exam of skin scrapings, hair stubs/roots, nail clippings

shows hyaline, septate hyphae

o Wood’s Lamp Examination

Fluorescence in cases of tinea capitis cause by Tinea schoenleinii, Microsporum canis and Microsporum audouinii

4

o Culture on Mycobiotic Agar

Cultural and morphological; characteristics used in species identification

CONFIRMATORY TESTS:

Hair Penetration Test – distinguishes Tinea mentagrophyte from Tinea rubrum

o Urease Test - distinguishes Tinea mentagrophyte from Tinea rubrum

NOTE: In annular lesions with central clearing and advancing border sample is obtained from the edge to yield a more

positive result and prevent false negative

Dermatophytes have no blastoconidia because they are not a budding yeast

They are seldom cultured

7 DIFFERENT TYPES OF DERMATOPHYTOSES:

TINEA CAPITIS

CAUSES: Microsporum species and Trichophyton species

Types of Tinea capitis with different causative agents:

o Microsporum audouinii infections

grey patches covered with scales develop with broken stumps of the infected hair

hair stumps are surrounded by spores hence ECTOTHRIX type of hair infection

o Kerion

Greater inflammatory reaction caused by Microsporum canis

Caused by spores of animal origin

A severe inflammatory type characterized by boggy, tumid, suppurating mass studded with pustules and broken

hair.

When the condition resolved, there may be areas of permanent hair loss.

o “black dot” tinea capitis

produced by Tinea violaceum and Tinea tonsurans

hairs are invaded within the shaft hence ENDOTHRIX type of hair infection

it breaks off at the surface of the hair shaft leaving stumps that look like black dots in the follicles

NOTE: An endothrix infection will always indicate that the pathogen is anthrophilic in origin

o Favus

Caused by Tinea schoenleinii

Affects mainly the scalp and is characterized by scutula (cup-shaped disc around the hair follicle with a peculiar

moussy odor) and cicatricial alopecia

ENDOTHRIX


o Wood’s light – suspected hair infection should always be examined under Wood’s light (UV >365 nm) as lesion of M.

canis and M. auduoinii show a diagnostic brilliant yellow-green fluorescence. Those due to T. schoenleinii may cause a

grey-green fluorescence.

o Direct microscopic examination

o Culture

TINEA BARBAE

CAUSES: Microsporum species and Trichophyton species acquired from animals



o Culture

TREATMENT:

o Systemic griseofulvin

o Clipping or shaving the beard is recommended

TINEA CORPORIS

CAUSES: Microsporum species, Trichophyton species and Epidermophyton floccosum

o Microsporum species are the predominant cause of tinea corporis in children

TINEA IMBRICATA

CAUSE: Trichophyton concentricum


o Direct microscopic examination of scrapings in 10%-20% KOH

o Culture

TINEA CRURIS

5

CAUSES: T. mentagrophyte or T. rubrum, E. floccosum



o Culture

TINEA PEDIS


o T. mentagrophyte commonly produces an inflammatory type of tinea pedis whereas T. rubrum produces a chronic type



o Culture

TINEA MANUUM




o Culture

TINEA UNGIUM

CAUSES: Trichophyton species and E. floccosum


o Direct microscopic examination of the nail

o Culture

TREATMENT:

o All nail infections are extremely resistant to treatment

o Systemic griseofulvin after identification of the agent

Dermatophytoses Location

Tinea capitis Scalp hair

Tinea barbae Beard hair

Tinea corporis Non-hairy smooth skin

>Tinea imbricata

Tinea cruris Groin

Tinea pedis Interdigital spaces of feet

Tinea manuum Hand

Tinea ungium Nail

III. Subcutaneous Mycoses

It is characterized by deep ulcerating lesions usually developing at the site of the trauma where the fungus is implanted.

It involves the deeper layer of the dermis, subcutaneous tissues and bone systemic spread.

Mimics some bacterial infections, with the exception of sporotrichosis

Causative organisms are ubiquitous in nature, cultural isolation wouldn’t be enough. Tissue invasion must be demonstrated by KOH

and tissue preparations.

Sporotrichosis

A. Etiology

Sporothrix schenckii

Yeast forms inside infected tissues

At 250, the fungus is a mold

B. Laboratory Diagnosis

Clinical materials use in laboratory examination include pus from abscesses, biopsy materials of subcutaneous or organ

lesions or sputum in cases of pulmonary infection

KOH mount is not diagnostically useful since organisms are sparse

Round to oval to cigar-shaped yeast cells can be demonstrated better with GMS stain rather that tissue smears

Asteroid bodies represents the host immune response (basophilic yeast surrounded by eosinophilic rays)

Culture is necessary to confirm diagnosis; colonies are initially white and membranous becoming black and leathery by age

Mycetoma (Madura Foot)

6

It is characterized by swelling, abscess formation and draining

A. Etiology

Eumycetoma (true fungi) Exophiala jeanselmei, Pseudallescheria boydii, Madurella mycetomatis and Madurella grisea

Actinomycetoma(bacteria) Actinomadura madurae, Actinomadura pelletieri, Streptomycis somaliensis, Nocardia braziliensis,

and Nocardia asteroids

B. Epidemiology

Saprophytes from the soil and is acquired by direct inoculation

C. Laboratory diagnosis

So that you can distinguish between a bacteria and a fungal infection

KOH examination (Direct microscopic examination) presents granules that shows the etiologic agents; color is species

specific

Culture is also use to identify the species

Chromomycosis

Dark brown nodules at site of infection

A. Etiology

Dematiaceous (black) fungi

Fonsecaea pedrosoi, Foncecaeae compactum, Phialophora verrucosa and Cladosporum carrionii


KOH in skin scrapings or histopathological infection; crushed black dots appear as thick walleddark brown, 5-12 mm in

diameter, round and sclerotic bodies with single or multiple cells formed by crosswalls

Brown, blanched distorted hyphae may also be present

Culture techniques are also done for taxonomic identification; slow growing, black colonies

Phaeohyphomycosis

Localized subcutaneous infection forming granulomas, cysts and abscesses.

A. Etiology

Several dematiaceous fungi


Histopathological examination; Organisms are seen as pigmented, septate hyphal fragments

Culture for taxonomic identification; dark colored colonies develops

IV. Opportunistic Mycoses

Candidiasis

A. Etiology

Candida albicans, C. tropicalis, C. krusei, C. parapsilosis and C. glabrata

B. Clinical disease

1. Superficial Candidiasis

The most common diseases involves the skin, nails and mucosal surface of the vagina, mouth esophagus and the

bronchial tree; Skin and nail infections usually mimics dermatophytoses

Cutaneous mycoses as seen in diabetics

Candidiasis of the nail usually causing hardening and thickening of the nail

Vulvovaginal candidiasis is also seen in diabetics and can be transferred sexually

Thrush (oral) usually presents white, creamy patches on the mucus membranes and corners of the mouth

C. Laboratory Diagnosis

KOH examination of the infected nail, skin, mucosal scrapings; in most instances, blastoconidia are seen singly or in

clusters at the constrictions of their pseudohyphae

Histopathological examination of C. albicans are demonstrated as budding yeast of pseudohyphae or both

Culture; in isolation media, C albicans grows as opaque cream colored colonies with pasty consistency while in microscopic

examination, pseudohyphae with clusters of round blastoconidia are seen

Germ tubes at 370 in serum identifies C. albicans

7

SYSTEMIC MYCOSES

- Most serious of all mycoses

- Originate primarily in the LUNGS

- Major types:

Endemic Respiratory Mycoses

A. Histoplasmosis

B. Blastomycosis

C. Coccidioidomycosis

D. Paracoccidioidomycosis

E. Penicilliosis marneffei

Opportunistic Mycoses

A. Candidiasis

B. Aspergillosis

C. Cryptococcosis

D. Zygomycosis

Endemic Respiratory Mycoses

- Portal of entry: Respiratory Tract

- Mode of Transmission: Inhalation of infectious conidia

- Infectious form: conidia (asexual form)

Agents:

- have restricted geographic distribution (area where the fungi thrive)

- exhibit thermal dimorphisms with 2 forms:

Yeast – seen at 37 degrees Celsius

Mold – seen at room temperature, natural habitat

- primary site of infection = lungs

- Microconidia – infectious form; the small the size, the better.

MYCOSES OCCUR AS CAUSED

BY

INFECTIOUS

PARTICLE

DIAGNOSIS (KOH/

histopath exam) →

TISSUE FORM

CULTURE AT ROOM

TEMPERATURE

(Saboraud’s Agar)

27C

At 37 Celsius (BHI)

Histoplasmosis

/

Darling’s/

Caver’s/

Spelunker’s

disease

Pulmonary (PTB

like) 60%

asymptomatic and

40% primary

pulmonary

histoplasmosis

Disseminated

infection with

(RES)

Reticuloendotheli

al System

involvement and

muco-cutaneous

infection

Histoplasm

a

capsulatu

m

Ascomycet

e

-Thermally

dimorphic

-

facultative

intracellula

r

-grows in

soil

contaminat

e by bat or

bird

excreta

Microconidia

(can easily go

through the

lungs and

settle in the

alveoli)

Small round to oval

intracellular yeast

cells often with

histiocytes

finding yeast cell in

tissues does not

diagnose

Histoplasmosis,

others are

histoplasma

fine septate hyphae

(hyaline)

tuberculate

macronidia (means

spikes around the

structure) and small

micronidia (both

seen in Lactophenol

Cotton Blue Mount)

which is diagnostic

of H. capsulatum

(infectious particle)

non-capsulated

creamy, pasty yeast

colonies

small oval yeast cells

(cluster – self yeast

cells)

non-infectious,

patient can’t transmit

Importance of

observation at Body

Temp: Demonstrate

dimorphism: Hyphae

(from culture)

yeast cell (seen

microscopically,

budding not

intracellularly)

Blastomycosis

aka “North

American

Blastomycosis’

PTB – like but

with lesser

calcifications

Cutaneous –

result of infection

of the skin or

sometimes a

manifestation of

disseminated

form;

microabscesses;

crusty, elevated

lesions

Disseminated –

with lower

percentage

Blastomyc

es

dermatitidi

s

Ascomycet

e

-Thermally

dimorphic

- soil

saprophyte

“conidia” /

microconidia

(No

macroconidia

)

Round, double-walled

yeast often with

single bud connected

by a broad base

(bowling pin

appearance)

Pyriform conidia

borne singly on

septate hyphae (on

Lactophenol Cotton

Blue mount)

Double-walled yeast

cells with single

broad-based bud

seen also in

KOH/histopath

8

MYCOSES OCCUR AS CAUSED

BY

INFECTIOUS

PARTICLE

DIAGNOSIS

(KOH/

histopath

exam) →

TISSUE FORM

CULTURE AT ROOM

TEMPERATURE

(Saboraud’s Agar)

At 37 Celsius (BHI)

Coccidioido

mycoses/

San

Joaquin

Valley fever

(found in

California,

an endemic

area)

PTB like with egg

shell cavity on x-ray

Disseminated

Meningitis: common

cause of death

Coccidiode

s immitis

Deuteromy

cete

(asexual

only)

-Thermally

dimorphic

-soil

saprophyte

Arthoconidia

- rectangular

shaped, thallic

conidiogeny

(conidia formed

inside hyphae)

-an asexual spore

which can be

disseminated by

fragmentation of

septate hyphae

and blastic yeast

cells

Hyphal fragments

produce

arthroconidia

Spherules

containing

endospores –

(not infectious)

Hyphae bearing

cylindrical, barrel-

shaped arthrocondia

separated by

dysjunctor cells

(empty degenerate

cells)

White floccose

colonies

No yeast-like colonies

on routine mycology

agar

Paracoccidi

oidomycosi

s

South

American

Blastomyco

sis/ Lutz-

Splendor-

Aleida’s

disease

a new

disease

PTB-like

Disseminated (oral

and nasal mucosa):

hepatosplenomegaly

is prominent

chronic

granulamatous lesion

or mulberry lesion

sometimes with

cervical adenitis

skin of face-most

common site of

infection

dimorphic and

pigmented

Paracoccid

ioides

braziliensis

Deuteromy

cete

(asexual

only)

-Thermally

dimorphic

- soil

saprophyte

Conidia Large, thin-

walled yeast

cells, with

multiple narrow

based buds

Septate hyphae with

no typical pattern

sporulation

Yeast cells with ship’s

or mariner;s wheel

appearance.

Penicilliosis

marneffei

produces

pigment

colonies

Pulmonary

disseminated (RES)

restricted to SEA

(Southeast Asia) –

Thailand (most

common in Chang

Mai areas)

Endemic – due to

mode of transmission

Opportunistic – they

affect

immunocompromised

px

naturally occurring

infections in bamboo

rats

new discovery

Penicillium

marneffei

-only

Penicillium

species

that is

thermally

dimorphic

– soil

saprophyte

Conidia Small, ovoid

yeast cells with

transverse

septum

Yeast cell

reproduction is

by tranverse

fission/

schizogony

Conidiophore

branch into metullae

which support the

phialides that bear

chains of conidia

Colonies produce

diffusible red

pigment → distinct

character of P.

marneffei (other

penicillium have

yellow pigment)

“Penicillus” –

paintbrush/fingerlik

e appearance

Round to oval cells

with crosswalls.

Opportunistic Mycoses

MYCOSES OCCUR AS INFECTIOUS

FORM

CAUSED BY DIAGNOSIS → TISSUE

FORM

CULTURE AT ROOM

TEMPERATURE

Candidiasis Yeast cells,

pseudohypha

e

Candida spp.

C. albicans (most

common)

Gram Stain/KOH/

histopath exam: small

budding yeast cells

and pseudohyphae

Germ Tube test:

Specific for C.

albicans

Pseudohyphae with

clusters of round

blastoconidia

Chlamydosores, yeast

cells and pseudohyphae

roduced on

chlasmydospore/cornme

al agar

9

MYCOSES OCCUR AS INFECTIOUS

FORM

CAUSED BY DIAGNOSIS → TISSUE

FORM

CULTURE AT ROOM

TEMPERATURE

Aspergillosis Allergic form – most

important

allergic bronchopulmonary

aspergilliosis

Asthmatic attack or hay

fever

Aspergilloma – “fungus

ball”

formation of intertwining

hyphal elements in

previous TB cavities.

Disseminated – invasive

aspergillosis

Conidia

Aspergillus spp.

A.fumigatus (most

common)

-soil saprophyte

-Monomorphic mold;

has a different sporing

head than penicillium

KOH/histopath exam

Wide, septated,

dichotomously

branced (acute angle)

hyphae - distinct

characteristics.

Conidiophore

supports swollen

vesicle covered by

phialides bearing

radial chains of

conidia

Sporing head with rows

of phialides bearing

conidiospores

Conidiospores arise from

“foot cell”

Cryptococcos

is

also called

Busse-

Buschke’s

disease or

torulosis

Pulmonary

(cryptococcoma)

-a solitary pulmonary

nodule in the mediastinum

mimicking a carcinoma.

Disseminated

-have a tendency for CNS

infection causing

meningitis.

Non-

capsulated

yeast cells

which is

smaller

because it

loses its

capsule.

Monomorphi

c yeast.

1. Cryptococcus

neoformans

(Filobasidiella

neoformans)

-in pigeon excreta

-affect the

immunocompromised

-Clinical disease:

Meningoencephatlitis

2 biotypes:

a. Cryptococcus

neoformans var.

neoformans.

→ Serotype D

b. Cryptococcus

neoformans var. grubii

Serotype A

2.Cryptococcus gatti

(Filobasidiella

bacillispora)

-soil under Eucalyptus

tree

→ Serotype: B,C

-affect the

immunocompetent

-Clinical disease:

pneumonia

India ink/histopath

exam

India ink-negative

stain (stains

background)

Yeast cells with wide

capsule.

Creamy, mucoid yeast

colonies.

Encapsulated yeast cells

Bird Seed agar (Niger) -

brown to black pigment

colonies due to melanin

protein due to

phenyloxidase produced

by the organism.

Chemical test: Urease

Test (+) – pink color

Caffeic Acid Test: (+) –

phenoloxidase

production

L-canavarine-glycine-

bromthymol blue (CBG

medium)

- C. neoformans

(yellow)

- C. gatti (blue)

Serologic test: antigen

detection - latex

agglutination & ELISA

Zygomycosis

/

Mucormycosi

s

- Rhinocerebral

- Pulmonary

- Cutaneous

- GIT

- Disseminated

Sporangiospo

re born

inside the

sporangium

Conidia – not

contained in

a

sporangium;

produced by

septate.

Filamentous fungi

belonging to

Phylum Zygomycota –

asexual

sporangiospores

Class Zygomycetes

(asexual and sexual

form)

Asexual → conidia

Sexual → zygospore

Genera:

1.Rhizopus

2.Mucor

3. Absidia

→ 1st 2 genera – more

common

KOH/histopath exam

Aseptate, wide

hyphae branching at

right angle.

Wide, ribbon like.

Morphologic features:

1. Rhizopus spp.

sporangia around

sporangiosphores

unbranched, nodal

columellae

hemispherical

no collarette

remains when

sporangia ruptures

rhizoids well

develop.

2. Mucor spp.

sporangia round

sporangiospores

branched,

internodal

no rhizoids

columellae round to

oval

3. Absidia spp.

sporangia pyriform

apophysis with

colarettes remain

when sporangia

ruptures

rhizoids

rudimentary.

Documents

Mycology Review