MYCOLOGY

HISTORY, SCOPE
&
CLASSIFICATION
Mycology : Systematic study of fungi

A fungus is a member of a large group of eukaryotic organisms (yeast

and molds) classified as a kingdom, Fungi

Scope :
1. Genetic and biochemical properties,
2. Taxonomy and classification,
3. Use to humans as a source of medicine,
4. food, and
5. psychotropic substances consumed for religious purposes,
6. dangers, such as poisoning or infection
History:
Year Scientist Contribution
Ringworm - first to be recognized and
reported
1588 Giambattista della Porta Observed fungal spores for first time
1601 Clusius Publishes Rariorum plantarum historia, the
first monograph written on fungi, which
described 105 species, in 47 genera
1671 Marcelo Malpighi Described various molds, such
as Rhizopus, Mucor, Penicillium
1673 Antony van Leeuwenhoek in a letter to the Royal society of London,
describes the presence of the yeast S.
cervease in fermented beer, the first
observation of yeast cells

1729 Micheli Germination of spores in same fungi

1761 - 1836 Christian Hendrik Persoon Classification of mushrooms.
Founder of modern mycology
1815 Mayer and Emmert Discovered Aspergillosis
 Year Scientist Contribution
1839 Lagenbeck First demonstrated yeast like fungus in
thrush
1843 Gruby Named Microsporoum audouinii as a
causative agent of ringworm in children
1866 DeBary Gives a broad classification of the fungi
1794 - 1878 Elias Magnus Fries Classify fungi (Spore color, microscopic
characteristics)
1900 Seeber Described the causative agent of
Rhinosporidiosis
1912 Meyer blastomycosis in dogs
1913 Zschokke First animal case was reported in horse
1918 Giltner reported first naturally occurring case of
Cocci-dioidomycosis in animals (cattle)
1928 Mucor pusillus was isolated from a nodule in
horse
1952 Holzworth First reported Cryptococcosis in cat
1953 Hughes Differentiates eight main sections
of hypomycetes on the basis
of condiophore and conidium development
 Systemic classification of fungi

KINGDOM : MYCOTA
Divisions
Phycomycota Algal fungi
Phytopththora albugo
Primitive fungi
Oomycota Coenocytic hyphae
Sexual reproduction
Zygomycota Conjugation fungi
Mucor spp.

Ascomycota Sac fungi

Candida spp.
Advanced fungi
Eumycota Septate hyphae
Sexual reproduction
Basidiomycota Club fungi
Puccinia agaricus

Sexual reproduction
Fungi imperfecti Deuteromycota Fusarium spp.
not identified
 Structural classification of fungi
Two basic morphological forms
1. Yeasts
2. Molds

Yeasts are unicellular fungi which reproduce asexually

by blastoconidia formation (budding) or fission.

Yeast like fungi are fungi showing yeast form with germination tubes
(pseudohyphae).

Molds (hyphal) are multi-cellular fungi which reproduce asexually and/or

sexually. Asexual reproduction does not involve genetic
recombination between two sexual types whereas sexual
reproduction does involve genetic recombination.

Dimorphism is the condition where by a fungus can exhibit either yeast or

hyphal form, depending on growth conditions. Very few fungi
exhibit dimorphism.
 Morphology
&
General Characteristics
Morphology: Eukaryotic multicellular organisms

a diploid number of chromosomes

a nuclear membrane
sterols in their plasma membrane
Genetic complexity
morphologic complexity

Filaments ----- Hyphae

Cells ----- long and thread-like and connected end-to-end

Another feature of fungi is the presence of chitin (a long
carbohydrate polymer) in their cell walls.

The body of the organism is given the special

name mycelium

When reproductive hyphae are produced, they form a

large organized structure called a sporocarp.

In addition to being filamentous, fungal cells often have

multiple nuclei.
Asexual fruiting structure Asexual fruiting structure
of Aspergillus species, illustrating of Rhizopus species, illustrating
septate hyphae, conidiophore, sporangium, sporangiophore,
vesicle, phialides and conidiospores. sporangiospores, coenocytic
hyphae and rhizoids.
A mass of hyphal elements is termed
the mycelium (synonymous with mold).

Aerial hyphae often produce asexual reproduction

propagules termed conidia(synonymous with spores).

Relatively large and complex conidia are

termed macroconidia

The smaller and more simple conidia are

termed microconidia.

When the conidia are enclosed in a sac (the sporangium),

they are called endospores.

The presence/absence of conidia and their size, shape and

location are major features used in the laboratory to
identify the species of fungus in clinical specimens.
Aspergillus flavus Aspergillus Aspergillus niger Aspergillus ocraceus
fumigatus
Mucor spp. Rhizopus spp. Penicillium spp. Fusarium spp.
Trichophyton spp. Microsporum spp. Epidermophyton Alternaria spp.
spp.
Candida spp. Melassezia spp. Geotrichum spp. Paeciliomyces spp.
Reproduction
Strategies of Reproduction
 Fungal Reproduction

Zygomycetes spp. Blastomycetes spp.

Ascomycetes spp. Yeast spp.
 Rhinoproridium spp.

Endoconidia
increase in size

Juvenile
sporangia
Mature
sporangia &
Endoconidia
release

Juvenile sporangia
Early mature increase in size
sporangia
Nutrition
Fungi

CHEMOHETEROTROPHIC

- Chemo-organotrophic

Synthesize required organic compounds and

energy from

• pre-existing organic sources in their

environment

• using the energy from chemical reactions

Fungal protoplasm is protected by a RIGID WALL.

Hence, fungi must obtain nutrients by

ABSORPTION.

SMALL MOLECULES
(e.g. simple sugars, amino acids)
absorbed directly across the fungal wall and plasma
membrane.

LARGER, MORE COMPLEX MOLECULES

(e.g. polymers such as polysaccharides and
proteins)
broken down into smaller molecules and then
Degradation of large molecules

• Takes place outside the fungal cell or hypha

• Achieved by extracellular enzymes which
are either released through or are bound to
the fungal wall.

Water is essential for the diffusion

of extracellular enzymes and nutrients
across the fungal wall and plasma
membrane, actively growing fungi are
usually restricted to relatively moist (or
humid) environments.
Cryptococcosis
Cryptococcosis

a systemic fungal disease

• Cryptococcosis, the most
common systemic mycosis
in the domestic cat, is
caused by an encapsulated
yeast—most commonly
Cryptococcus neoformans
and C gattii, both
dimorphic,
basidiomycetous fungi.
Morphology
• A true yeast
• Round 4 – 10 microns
• Surrounded by
Mucopolysaccharide capsule.

Reproduction
• asexual and sexual phases.
• Asexual phase is haploid.
• Sexual phase is by budding basidiospores
(i.e. infectious component of Cryptococcus)
• Culturing on Sabourauds agar, and incubated at 370 C
for up to 3 weeks
• Cultures appear as Creamy, white, yellow Brown
colored Simple urease test helps in confirming the
isolate.
Host
Common in cats but also is seen in dogs, cattle,
horses, sheep, goats, birds, and wild animals.

Affect the respiratory tract (especially the nasal

cavity), CNS, eyes, and skin (particularly of the
face and neck of cats).
Causative agent
Cryptococcus neoformans and C gattii

Infection occurs worldwide.

The fungi are found in soil and fowl manure, especially in pigeon
droppings.
Exist in the environment and in tissues in a yeast form.

Transmission
inhalation of spores or contamination of wounds.
In avian droppings, it may occur in a noncapsulated form as small
as 1 μm, which can be inhaled into the deeper portions of the
lungs.
Bovine cryptococcosis

Associated only with cases of mastitis, and many cows in a herd

may be infected.

Affected cows
• anorexia,
• decreased milk flow,
• swelling and firmness of affected quarters, and
• enlarged supramammary lymph nodes.
• The milk becomes viscid, mucoid, and gray-white, or it may
be watery with flakes.

Equine cryptococcosis
Respiratory ailment with obstructive growths in the nasal cavities.
In cats

upper respiratory signs secondary to nasal cavity infection

are most common

• sneezing;
• mucopurulent, serous, or hemorrhagic unilateral or
bilateral chronic nasal discharge;
• polyp-like mass(es) in the nostril;
• a firm, subcutaneous swelling over the bridge of the
nose.
In cats

Cutaneous lesions
• characterized by papules and nodules.
• Larger lesions tend to ulcerate, leaving a raw
surface with a serous exudate. Neurologic signs
associated with cryptococcosis of the CNS may
include depression,
• changes in temperament,
• seizures, circling, paresis, and blindness.
• Ocular abnormalities,
• including dilated unresponsive pupils and
blindness due to exudative retinal detachment,
• granulomatous chorioretinitis, panophthalmitis,
and optic neuritis.
Diagnosis
• cytologic evaluation of nasal exudate, skin exudate, CSF, or samples
obtained by paracentesis of the aqueous or vitreous chambers of the
eye
• by impression smears of nasal or cutaneous masses.
• Gram stain is most useful; the organism retains the crystal violet,
whereas the capsule stains lightly red with safranin.
• India ink is also used to visualize the organism, which appears unstained
and silhouetted against a black background.
• Wright stain has been used most often in diagnosing canine and feline
cases, but this stain can cause the organism to shrink and the capsule to
become distorted.
• New methylene blue and periodic acid-Schiff (PAS) stains are better
than Wright stain.
• a biopsy of the lesion can be taken for culture and histology.
• Detection of cryptococcal capsular antigen in serum, urine, or CSF is a
useful.
• A latex agglutination test.
• Microscopy and
staining: Cryptococcus
neoformans appear as a
spherical, single or multiple
budding, thick walled yeast
that is 2-15 μm (wide variation
in size) in diameter.
• It is usually surrounded by a
wide refractile capsule.
• India ink preparation of CSF
sample India ink
preparation when positive in
CSF is diagnostic of
cryptococcal meningitis but its
sensitivity is low
Treatment

• Fluconazole (2.5–10 mg/kg/day)

• Itraconazole (10 mg/kg/day)

• Amphotericin B (0.5–0.8 mg/kg)

Candidiasis
Candidiasis
A localized muco-cutaneous disease
Caused by yeast-like fungus Candida albicans
Distributed worldwide in a variety of animals
C. albicans is a normal inhabitant of the nasopharynx, GI
tract, and external genitalia
Opportunistic pathogen
When it affects the mouth, it is commonly called thrush
Predisposing factors
Disruption of mucosal integrity
indwelling, intravenous, or urinary catheters
Antibiotics therapy
Immunosuppressive drugs
Immunosuppressive diseases.
 Morphology & Growth requirements

• Pleomorphic
• Grows as ovoid "yeast" cells.
• Mild environmental changes in temperature, CO2,
nutrients and pH can result in a morphological shift to
filamentous growth.
Shape: spores and hyphae (branching tubes that make up
the body of a multicellular fungus)
Size: 10-12 µm in diameter
pH: Needs a slightly alkaline environment to thrive , a pH
about 7.4
Temperature: 37°C, warm and damp environments
Oxygen: Facultative anaerobes
 Media
• The basic culture media used is blood agar,
• Potato Dextrose Agar (PDA) or broth (PDB),
• Sabouraud brain heart infusion agar,
• Sabouraud Dextrose Agar (SDA) or broth (SDB),
• Yeast Nitrogen Base (YNB) and
• Yeast Potato Dextrose (YPD) agar or broth.
 Cultural charcteristic

• C. albicans is present, short, slender, tubelike

structures (germ tube) can be observed under the
microscope (KOH digests keratin and glycerine
prevents degradation of yeast.
• Lactophenol cotton blue can also be used together
with KOH for better observation of yeast under
brightfield microscope.
• Gram and Giemsa stains are useful in staining yeast
cells because of their small size (3-4 μm).
• Calcofluor white, a colourless dye can be used to
detect fungal elements.
 Reproduction
• Candida which reproduce through budding and are
typically a yeast cellular of candida albicans.
• They produce bud which fail to detach and become
elongated, producing a chain of elongated yeast cells
called pseudohyphe.
 Pathogenicity
• C. albicans is normally present on the skin and in
mucous membranes such as the, mouth, rectum, and
digestive tract
• Fibronectin receptor on Candida albicans facilitates
its adherence to the epithelium of the gastrointestinal
or urinary tract.
• Hydrophobic molecules on the surface of Candida
also helps in adhesion.
• Aspartyl proteases found in C. albicans has shown
increased ability to cause disease in animal models
• Phenotypic switching and presence
of phospholipase also play a role in pathogenesis.
 Birds
A mycotic disease of the digestive tract of young chickens, turkeys,
and quail caused by Candida albicans.
Commonly develops after use of therapeutic antibiotics or when
using unsanitary drinking facilities.
Lesions
Found in the crop
thickened mucosa and whitish, raised pseudo-membranes.
The same lesions in the mouth and esophagus.
Occasionally, shallow ulcers and sloughing of necrotic epithelium.
Signs
Listlessness and inappetence.
Diagnosis
Gross lesions, histopathology, Culture of the organism
Pigs and foals
Superficial infections limited to the mucous
membranes of the intestinal tract.

Cattle, sheep, horses and foals

Systemic candidiasis secondary to prolonged
antibiotic or corticosteroid therapy. Mastitis and
abortion in cattle. Arthritis in horses
Cats
Rare but associated with oral and upper
respiratory disease, pyothorax, ocular lesions,
intestinal disease, and urocystitis.

Dogs
Rare.
• Fungemia and Candida peritonitis with
perforating intestinal lesions after surgery.
• Mucosal and cutaneous candidiasis noted in
immunosuppressed dogs and in dogs with
diabetes mellitus.
Diagnosis

• Examination of scrapings or biopsy specimens from

mucocutaneous lesions.

• C. albicans are ovoid, budding yeast cells (2–4 μm)

with thin walls

• Produce pseudohyphae when the blastospores

remain attached after budding division.

• Filamentous, regular, true hyphae also may be

visible.
Treatment

• Nystatin ointment or topical application of

amphotericin B

• 1% iodine solution may be useful in the

treatment of oral or cutaneous candidiasis

• Amphotericin B
• Fluconazole (5 mg/kg/day, PO, for 4–6 wk)
• Itraconazole and amphotericin B lipid complex
treatments of choice in dogs
Aspergillosis
 Introduction
• Aspergillosis : spectrum of diseases
• Uncommon, immunocompromised animals
• feline immunodeficiency virus
• chemotherapeutics
• renal transplants
• canine sinonasal aspergillosis
• equine guttural pouch mycosis
• bovine mycotic abortion
• cetacean mycotic pneumonia caused by Aspergillus spp.
• brooder pneumonia
Aspergillosis include

• Mycotoxicosis (ingestion of contaminated food)

• Allergy
• Colonization without extension in preformed
cavities
• Invasive
• Systemic and fetal disseminated disease
 Important Species
• A. fumigatus
• A. flavus
• A. niger
• A. terreus
Life cycle
 Diseases caused
In birds,

Aspergillosis is primarily bronchopulmonary

dyspnea,
gasping, and
polypnea,
anorexia,
emaciation.
 Diseases caused
Ruminants: may be asymptomatic

– bronchopulmonary form (Mycotic pneumonia)

– mastitis

– placentitis and abortion

• In Horses
– epistaxis (unilateral intermittent epistaxis )and
dysphagia (Guttural Pouch Mycosis).
– fetal if associated with diffuse pulmonary invasion

• In Dogs , aspergillosis is typically localized to the

nasal cavity or paranasal sinuses and is usually
caused by infection with A fumigatus.

• In Cats , sinonasal and sino-orbital disease is seen

most often
 Brooder pneumonia
• during hatching in contaminated incubators
• by inhalation of spore - laden litter.
• Dyspnea, hyperpnea, signs of nervous system
involvement, inappetence, emaciation, and increased
thirst may be seen.
• up to 6 wk old
• the lungs are most frequently involved.
• Lesions on PM: white to yellow plaques and nodules
• mycelial masses may be seen within the air passages
Diagnosis:

• by culture
• microscopic examination of fresh
preparations.
• pure culture of the organism.
• histopathologic examination
Dermatophytosis
 Dermatophytosis
• Dermatophytes are fungal organisms that are
able to exist within the keratinous elements of
living skin and which belong to one of 3
genera,
• Epidermophyton
• Microsporum,and
• Trichophyton.
• Dermatophytes require keratin for growth
and therefore infect hair, nails, and
superficial skin, with clinical manifestations
named for the area affected.
• Dermatophytes have the ability to utilize
keratin as a nutrient source, i.e. they have a
unique enzymatic capacity [keratinase].
• Other enzymes also secreted by dermato-
phytes are elastases and proteinases,which
cosidered as virulence factors.
 Occurance
• Dermatophytoses occur in all populations
worldwide, but are generally more common
among immunocompromised patients.
• • Tinea infections have alternately been called
“ringworm,” because of the lesions that present
as a circular or oval clearing surrounded by a red,
scaly, elevated border (“ring”).
• Besides the dermatophytoses, superficial
infections may also result from infection with
other fungi, including the Malassezia species of
yeast, and candida.
 ETIOLOGIC AGENTS

• Three fungal genera cause tinea infections:

Microsporum, Trichophyton, and more rarely,
Epidermophyton .
• Species may be grouped by their source of human
infection
• • 1-Anthropophilic:from human, the most frequent
causes of onychomycosis and other superficial
dermatophytoses
• • 2- Zoophilic:from animals, especially dogs, cat. •
3- Geophilic: from soil, less commonly,
 IMMUNOLOGY
• The dermatophytes colonize keratinized
tissue of the stratum corneum; invasion
by anthropophilic species usually result in
less inflammation than that of zoophilic
or geophilic species.
• • The epidermis functions as a barrier to
microorganisms, and commensal flora
may also help reduce infection by
pathogens .
 PATHOGENESIS

• Entry into the stratum corneum may result from trauma

to the skin or some other breach of the skin barrier.

• • Excessive sweating and occlusive clothing /footwear

aid in providing a warm, moist environment conducive to
tinea infection.

• Infection may be transferred from one area of the body

to another.

• Infection may also be transmitted between individuals

by direct or indirect contact with scales containing fungal
arthroconidia from infected individuals
 Clinical symptomes

• red, scaly, itchy or raised patches

• patches may be redder on outside edges or
resemble a ring
• patches that begin to ooze or develop
blister
• bald patches may develop, when the scalp
is affected
• nails may thicken, discolour or begin to
crack
 Cultural charcteristic

• Dermatophytes are strict aerobes ,most

of which grow slowly on standard SDA.
• • Can resist cyclohexamide in the
medium.
• • A few require special growth factors,
which are supplied by the addition of
yeast extract to the SDA.
• • T.equinum needs nicotinic acid, and
T.verrucosum needs thiamine and inositol
for growth.
• Macroconidia and miroconidia are produced
in culture. • The cultures of many
dermatophytes are pigmented. • Colonial
morphology and the type of macro- conidia
produced are used for identification. •
Arthrospores are the infectious forms ,most
often associated with tissue invasion by this
group of fungi.
• Dermatophytes can be grouped on the basis
of their habitats and the host preferences as:
• • Geophilic
• • Zoophilic
• • Anthropophilic USUAL HABITAT
• Geophilic dermatophytes • Inhabit and replicate in
association with decomposing keratinous materials such
as hairs or feathers. • example: • Microsporum gypseum .
• . Zoophilic dermatophytes • Zoophilic species are
primarily parasitic on animals and infections may be
transmitted to humans following contact with the animal
host. example: 1. Microsporum canis 2. Trichophyton
equinum 3. Trichophyton verrucosum

• . Anthropophilic dermatophytes • The common

anthropophilic species are primarily parasitic on
man .They are unable to colonize other animals and they
have no other environmental sources. • For example: •
Epidermophyton fluccosum • Trichophyton rubrum •
Trichophyton mentagrophytes
Microsprum
Trichophyton equinum
• Trichophyton rubrum
 sample

• Direct microscopy
of infected
materials
• • Skin Scrapings,
nail scrapings and
epilated hairs
should be
examined using
10% KOH or
calcofluor white
mounts.
 Hair invasion
• • Hairs treated with KOH
should be examined
microscopically for the
presence of arthro-
spores. • The
arrangement of
arthrospores on hair is
called ectothrix,which
either:
• 1-Large ectothrix.
• 2-Small ectothrix. .
• Hair invasion
• 1-Large ectothrix,5-8 microns in sparse
chains inside and outside of hair such as:
M.gypseum,M.nanum,T.equinum
• 2-Large ectothrix in chains,which include:
a-Megaspores type(5-10 microns) e.g
T.verrucosum b-Microides type(3-
5microns) e.g T.mentagrophytes c-
Intermediate types e.g
T.rubrum,T.megninii
• Hair invasion • When the
arthrospores arranged
inside the infected hair, it
is typically endothrix,such
as:
• • T.
violaceum ,T.sodanense. •
Favic type: special type of
endothrix hair invasion in
which hyphae are not
break up into arthrospores
but die and left air
spaces.e.g.T. schoenleinii
 Laboratory diagnosis of dermatophytes
• A-Sampling: 1-Lesions should be cleaned by soap
& water or disinfected with alcohole 70% using a
piece of gauze.
• 2-A specimen of scales,nail or hair should be free
from extraneous material such as
dirt,sebum,ointments,antifungal agents, it should
first be removed with an alcowipe.
• 3-. Using a blunt scalpel, tweezers, or a bone
curette, firmly scrape the lesion, particularly at
the advancing border(peripheries of the lesions),
hair stumps are epilated by forceps.
• 5-Suitable material from cats can also be
collected on a large sheet of paper by
bruching the caot with a clean toothbrush
• • 6-Skin and nail specimens may be
scraped directly onto special black cards,
which make it easier to see how much
material has been collected and provide
ideal conditions for transportation to the
laboratory.
 Laboratory diagnosis of dermatophytes
• B-Ultraviolet (Wood’s
light) examination : •
Hair infected with
parasitic Mirosporum
spp may be detected by
the yellow green
fluorescence in
ultraviolet light.
• • The Wood’s light is
useful to detect M.canis
infection in cats,dogs
and other small animals.
• • In tinea capitis caused by parasitic Microsporum
species(M.canis,M.distortum,M.audouinii&
M.ferrugineum) the parasitized hairs are usually
but not always fluorescent yellow green.
• • T. schoenleinii gives dull green fluorescence.
• • Fluorescence is dependent on the host animal as
well as on the dermatophyte species.
• • The Fluorescence of hair with dermatophyte
infections appears to be due to treptophan
metabolites.
• D-Isolation of dermatophytes(culturing):
• 1-Specimens should be inoculated onto primary
isolation media, like Sabouraud's dextrose agar
containing cycloheximide (actidione) and
chloramphenicol
• ,incubated at 26-28C for up to 4 weeks.
• Isolation of T.verrucosum(cattle ringworm)is
favored at 37C.
• The growth of any dermatophyte is significant.
• 2-Multiple cultures are recommended whenever a
cotamination proplem can be anticipated,i.e it is
better to culture each sample onto more than one
tube.
• Laboratory diagnosis of dermatophytes
• 4-Dermatophyte test medium(DTM)has been
formulated to differentiate dermatophytes from
contaminating fungi.
• • Phenol red is used as a pH indicator in this
medium.
• • Growth of dermatophytes results in alkaline
metabolic products and the color of the medium
changes from yellow to red.
• • Other fungal media should be used in conjunction
with DTM because some contaminating fungi can
induce a color change.
• Laboratory diagnosis of dermatophytes
• • In addition,the color change in DTM can
obscure the characteristic pigmentation
required for differentiation of
dermatophyte species. A.Dermatophyte
Test Medium (DTM) Sterile medium yellow.
• B. DTM Positive DTM plate on the right
showing color change after two day's
growth; Microsporum canis
• There are three forms of colonies: • a-
Membranous form: the aerial mycelium is entirely
absent and the vegetative mycelium is in compact
masses e.g.T.verrucosum,T.violaceum….. • b-
Filamentous form: the aerial mycelium is more or
less high and dense
e.g.M.canis,M.rubrum,E.floccosum. • c-Granular-
powdery form:characterized by extensive conidia
and absence of aerial filaments e.g.
T.mentagrophytes,T.equinum.
• The isolated cultures are examined by the
following technique: 1-Wet mount technique.
• 2-Slide culture technique
(microculture technique).
• 3-Cellophane tape preparation.
RHINOSPORIDIOSIS,
ZYGOMYCOSIS
• ETIOLOGY-
• Rhinosporidium seeberi, a fungus presumed to
occur in nature(water) and that has not been
cultivated as yet on artificial media but has been
propogated in cell cultures.
Classification
MICROSCOPIC
MACROSCOPIC
• Causes a chronic,generally benign disease of
cattle,horses,mules,dogs,aquatic birds and humans
characterized by the formation of polyps on the
nasal and occular mucous membranes.
• More than 90% cases involve male animals.
• Disease occurs mostly in tropical and subtropical
countries.
• Infrequent cases-U.S
 Diagnosis
• Wet mounts from nasal discharge and sections
from polyps disclose large sporangia(200 to 300
µm) that contain thousands of endospores.
• The latter are released when the sporangia
rupture.
• Sporangia develop in tissue from small,globose
spores.
• Typical sporangia are seen in stained sections of
biopsy specimens.
 Zygomycosis
• Disease of animals and humans caused by
fungi of the order Mucorales
• Class-Zygomycota
• Genus-
Mucor,Rhizomucor,Absidia,Rhizopus,Mortierel
la,Cunninghamella and Sakesenaea which
occur widely as thrmotolerant saprophytes in
soil and decaying vegetation.
 Pathogenicity
• Mode of infection is mainly by inhalation or
ingestion.
• Oppurtinistic and are frequently secondary to
concurrent infections,metabolic acidosis or
immunosuppression.
• They may infect lymph nodes of the respiratory and
alimentary tracts.
• Lesions are granulomatous and occasionally
ulcerative and caseocalcareous.
• Ulceration of stomach and intestine.
• Lesions in swine –mainly found in mediastinal
and submandibular lymph nodes,embolic
tumours are seen in liver and lungs and fungi of
this group may be found in gastric ulcers.
• Lesions in cattle-bronchial,messentric and
mediastinal lymph nodes,there may be nasal
and abomasal ulcers.
• Mortirella wolfi-imp cause of bovine abortion
(mycotic placentitis),which is sometimes
followed by acute pneumonia and death.
• Also reported in
 Direct Examination
• Fragments and pieces of coarse,non
septate,branching hyphae –seen in smears
from lesions and biopsies.
• The coarseness and
 Lab Diagnosis
• Grow rapidly on SDA at room temp.
• They are common contaminants,hence isolation
alone is not necessarily considered significant.
• All have round sporangia borne on
sporangiophores,sporangia contain numerous
sporangiospores.
• Rhizomucor spp.
• Produce a thick,grey mycelium with few if any
rhizoids.sporangiophores are short,with
black,spherical sporangia.
• Mucor spp.
• Have a thick,colourless mycelum without
rhizoides.sporangiophores are simple or branched
and globose sporangia contain small spores.
• Absidia spp
• Sporangiophores do not arise from the stolons
opposite the rhizoides as in Rhizopus.however
• Rhizopus species-have dense,cottony,aerial
mycelium that aare first white and then turn
grey.sporangiophores arise from the stolons where
the stolons contact the medium through rhizoides.
• Mortierella spp-
• Grows on blood agar and SDA at 25-27 c and 37 c.
• Colonies on SDA and blood agars-
white,velvety,dense and characteristically
lobulated.
• The hyphae are hyaline,and sporangia are produced
on special media.
Mycotic abortions
• History
• The first record-Theobald Smith (1920)-
recovered fungus from foetal membranes-
• Mucor rhizopodiformis (Rhizopus cohnii)
• Gilman & Birch (1925) recorded actual abortion
• Predisposing factors
• Stored hay and straw-in high humidity and
temperature
 Etiology
• A.fumigatus –the main fungus for mycotic abortions in cattle
• Other species
• *A. nidulans
• A. niger)
• A. terreus
• *Allescheria boydii
• Monotospora lanuginosa
• *Absidia corymbifera
• *A. ramosa)
• Mortierella polycephala
• *Mucor pusillus
• Rhizopus-arrnizus
• *R. colinii Berl.
• Syn. Mucor rhizopodiformis
• R. microsporus (Syn. R. equinus )
• Candidada tropicalis
• Polystictus versicolor
 Transmission
• Inhalation
• Ingestion
 Pathogenesis
• Inhalation(lung mucosa)/ingestion
• Injury to the mucosa lesions in the respiratory
tract(or ulcers ,mycotic ruminitis etc.)
• In blood
• To placenta-foetal placentitis( slow-takes
about 1-2 months)
• Interfere with nutrition of foetus
• Death of foetus
 Symptoms/lesions

• No noticeable symptoms
• Appearance of the placenta and particularly
the cotyledons-greatly thickened, especially at
the margins and Central necrosis
• The intercaruncular areas- leather-like
consistency with discrete and confluent
thickenings
 Diagnosis
• Samples
• Placenta,
• The amniotic fluid,
• Foetal stomach contents and
• Foetal skin lesions
• Foetal organs (rare)
• Smear from foetal stomach content
• Isolation of fungus on Malt Agar (with Penicillin
20 units and streptomycin 40 units)
• In the foetal stomach contents and the
placenta the hyphae of Aspergillus fumigatus
are narrow, branching, septate and 1.5-3.0 u
wide.
• In culture - small bluish-green heads with the
typical structure of an Aspergillus.
• The Absidia spp. have hyphae 2.5-7.5 micra
wide, of a different appearance, much
branched, non-septate and irregular in outline
with numerous swellings.
• The cultural appearance -fluffy white growth
and the pear-shaped sporangia containing
large numbers of spores.
• The shape of the sporangia distinguishes them
from many species
• Mucor which have globose sporangia, but the
non-septate hyphae
• Yeasts appear as round, oval or elongated
budding cells and in culture
• usually form bacteria-like colonies
• which are opaque and may produce abundant
mycelium
Mycotoxicosis
• Mycotoxins are secondary metabolites of fungi
that are recognized as toxic to other life forms.
• Mycotoxicosis is used to describe the action of
mycotoxin(s) and is frequently mediated through
a number of organs, notably the liver, kidney,
lungs, and the nervous, endocrine, and immune
systems.
• Due to their diverse chemical structures,
mycotoxins may exhibit a number of biological
effects, including both acute and chronic toxic
effects as well as carcinogenic, mutagenic,
genotoxic, and immunotoxic effects.
Feeds Most Susceptible to Fungi-
producing Mycotoxins
• Corn
• Wheat
• Oats
• Barley
• Recently Sorghum
• Cottonseed
• Peanut meal
• Rye
 Aflatoxin-1
• cancer in animals.
• Primarily attacks the liver, in cases of cirrhosis,
necrosis, and carcinomas with a secondary affect
of immune suppression.
• Risk factor for neonatal jaundice, in areas of
maternal consumption.
• Does not stay in the body for long periods of
time, usually excreted within 96 hours, in animals.
• In milk, for human consumption, advisory level is
5 ppb.
 AFLATOXIN EFFECTS
• Inhibits protein synthesis
• Poor gain
• Liver damage
• Susceptibility to Infection
• Residues / carcinogenicity
• Reproduction in swine not primarily affected
 Aflatoxin Detection
• Black Light test - BYG fluorescence
– Abused. Use very carefully by trained people
– Presumptive test for organism, not aflatoxin
– Many other things fluoresce, including broken
soybean seeds
• Chromatography
– Including rapid minicolumn in-field tests
• Ochratoxins, are produced by a number of fungi in the genera
Aspergillus and Penicillium. The largest amounts ochratoxins are
made by A. ochraceus and P. cyclopium.
• Other fungi, such as Petromyces alliceus, A. citricus, and A.
fonsecaeus (both in A. niger group), have also been found to
produce OA. Most of the OA producers are storage fungi and
preharvest fungal infection.
• Zearalenone (ZE)
• a mycotoxin produced by the scabby wheat fungus, F.
graminearum (roseum), is of most concern. Also called F-2,
ZE is a phytoestrogen causing hyperestrogenic effects and
reproductive problems such as premature onset of puberty
in female animals,especially swine.
• ZE has been shown to bind with the estrogen and steroid
receptors, and stimulates protein synthesis by mimicking
hormonal action.
• Zearalenone can be toxic to plants; it can inhibit seed
germination and embryo growth at low concentrations.
• Natural contamination with ZE primarily occurs in cereal
grains such as corn and wheat
• Mycotoxins Produced by Other Fungi
• Sporidesmines, a group of hepatotoxins
discovered in the 1960s. These mycotoxins,
causing facial eczema in animals, are produced by
Pithomyces chartarum and Sporidesmium
chartarum and are very important economically
to the sheep industry.
• Slaframine, a significant mycotoxin produced by
Rhizoctonia leguminicola (in infested legume
forage crops).
 Fusarium
• Fungal species from the genus Fusarium will attack
corn and wheat plants.
• Most are plant pathogens and can be found in soil.
• Some examples of affected plants are corn, wheat,
barley, beans, with lesser contamination in rye,
triticale, millet, and oats.
• Trichothecene toxins target the circulatory,
alimentary, skin, and nervous systems.
 F. graminearum- Wheat
• Causes scab damage to kernels and
head blight.
• Produces deoxynivalenol (DON), also called
vomitotoxin.
• F. graminearum in Maize (Corn)
• Creates Giberella Ear Rot
• Produces the toxins: DON and zearalenone (ZEN),
and T-2 toxins.
• Have damaging effects on plants, humans, and
other animals with monogastric digestive processes.
 DON and T-2 Toxin
• These are tricothecenes of wheat, grain, and barley.
• They cause necrosis and hemorrhage of the
digestive tract, decreased blood production in the
bone and spleen, and changes to reproductive
systems.
• In poultry, causes reduced egg production, beak
lesions, and abnormal feathering
• Optimal temperature range is between 70 and 85
degrees Farenheit.
• Advisory level of DON is 1 ppm.
 Zearalenone
• A tricothecene.
• Mimics the body’s production of estrogen.
• Causes feminization of male animals.
• Disrupts conception, ovulation, and fetal
development in female animals.
• Pigs are especially sensitive, poultry and cows show
little sensitivity.
 F. moniliforme
• Plant pathogen most associated with corn. Also
found in rice, sorghum, yams, hazelnuts, pecans,
and cheeses.
• Diseases associated with this species include “crazy
horse disease” in horses, pulmonary edema in pigs,
liver cancer in rats, bone malformation in chicks
and pigs.
• The fumonisins produced by F. moniliforme are
linked with esophageal cancer in humans.
• Other toxins produced include fusaric acid, fusarins,
and fusariocins.
• Advisory levels are 5 ppm in animal feed.
 Penicillium Toxins
• Large genus with over 150 species.
• Discovered antibacterial properties within
genus, causing production of penicillin.
• 100 species have mycotoxins.
• Nine specific toxins affecting human health are
citreoviridin, citrinin, cyclopiazonic acid,
ochratoxin A, patulin, penitrem A, PR toxin,
Roquefortine C, and, Secalonic acid D.
• Separated into two groups: those that affect
liver and kidneys, and those that are
neurotoxic.
• Liver and kidney toxins are asymptomatic and
cause overall animal debility.
• Neurotoxins cause visible trembling.
 Ochratoxin A and Citrinin
• Affects kidney function.
• Causes Balkan nephropathy and Yellow Rice Fever
in humans.
• Chickens, turkeys, and ducklings are affected by
ochratoxicosis, causing poor weight gain, egg
output, and poor shell quality.
• Ochratoxin sources are peanuts, pecans, beans,
dried fruit and dried fish.
• Citrinin sources are in wheat, rice, corn, and flour.
• Citrinin is most associated with horses, pigs, dogs,
and poultry.
 Cyclopiazonic Acid (CPA)

• Found in corn and peanuts in Georgia.

• Chief species from Penicillium causes cheese
spoilage.
• Causes fatty degeneration in liver and kidneys
in animals, chickens are very susceptible.
• May act synergistically with aflatoxin.
Organ System Affected Toxin(s)

Vascular Aflatoxin
Digestive Aflatoxin, T-2toxin, Vomitotoxin
Respiratory Trichothecenes
Nervous Trichothecenes
Cutaneous Tricothecenes
Urinary Ochratoxin A, Citrinin
Reproductive Zearalenone, T-2 toxin
Immune Many
 Alternaria Toxins
• Infects the plant in the field, such as wheat,
sorghum, and barley.
• Also fruits and vegetables that can cause
spoilage in refrigeration.
• Toxins include: alternariol, alternariol
monomethyl ether, altenuene, tenuazonic acid,
and altertoxins.
• Little is know of these toxins; but, toxic effects
are seen in rats, chicks, ducklings, and turkeys.
 Mycotoxins
Factors causing variation in effects
• Species, breed
• Age
• Sex
• Nutritional status
• Other diseases
• Other mycotoxins
• Extent of exposure
 Other Mycotoxins of Growing Interest
• Ochratoxins
– Produced by Penicillium verrucosum and several
spp. Of Asperfillus.
– Potently nephrotoxic and carcinogenic,
teratogenic and immunotoxic.
– Public health problem, but little evidence of
problematic instances in swine.
• Fusarium
– Taxonomy is quite confusing
– Has had classification changed various times
– Fusarium roseum, Fusarium graminearum and
Gibberella zeae are all terms applied to the same
thing.
– Gibberella zeae is the “perfect” (reproductive)
stage
– Nickname “GIB” corn.
 Fusarium toxins
• Deoxynivalenol
– Feed refusal
– Emesis (so nicknamed “vomitoxin”)
• Zearalenone
– Estrogenic effects
 FUMONISON
• Deadly to horses
– equine leukoencephalomalacia
• Swine - pulmonary oedema
• Renal toxicity and hepatotoxicActually 8 analogs
known, only B1, B2 & B3 often found.
• ORGANISM is Fusarium moniliforme [=F.
verticillioides (Sacc.) Nirenberg] or F. proliferatum
• Fusarium moniliforme is VERY COMMON but
seldom produces mycotoxin.
 Fumonison - Levels
• < 5 ppm for Horses
• 10 ppm for swine
• 50 ppm for cattle
 Mycotoxin Effects on Animals
• Feed refusal.
• Impaired animal health, resulting in reduced
production of eggs, milk, weight gain, etc.
• Metabolites are passed through the milk in
cheese, dry milk, and yogurt.
• Disease.
• Death in animals.
Thank
You