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Mycology
Book list:
1
...
Microbiology With Diseases by Taxonomy
By Robert W
...
Microbiology: An Introduction
By Tortora
4
...

5
...
A
...
Introduction to Fungi 3rd edition
Cambridge University Press
7
...
Anaissie
8
...
Essentials of Clinical Mycology
By Kauffman

1

1
...
They are eukaryotic; cells contain membrane bound cell organelles including nuclei, mitochondria,
golgi apparatus, endoplasmic reticulum, lysosomes etc
...

2
...

3
...
All
fungi possess cell wall made of chitin
...
They are chemolithotrophs (require organic compounds for both C and energy sources) and fungi
lack chlorophyll and are therefore non-autotrophic
...
They obtain their nutrients by absorption
...
They obtain nutrients as saprophytes (live off of decaying matter) or as parasites (live off of living
matter)
...
All fungi require water and O2 and there are no obligate anaerobes
...
Typically reproduce asexually and/or sexually by producing spores
...
They grow either reproductively by budding or non-reproductively by hyphal tip elongation
...
Food storage is generally in the form of lipids and glycogen
...
They exhibit the phenomenon of alteration of generation
...
Some species grow as unicellular yeasts that reproduce by budding or binary fission
...

2
...
Fungi are the only organisms that combine these two
structural molecules in their cell wall
...

Structure of Fungi
1
...
They consist of
tubular cell wall made of chitin
...
Hyphae are either septate
(divided into cells with internal cross-walls called septa) or aseptate (coenocyte)
...
Hyphae grow by elongating at the tips
...
Mycelium: Cluster of hyphae interconnect and bundle up into a mycelium
...
They
also absorb the nutrients and produce fruiting bodies
...
Fruiting body: Fruiting body produces spores which are involved in fungal reproduction
...
Fruiting body is the only part of fungus that is visible to naked eye
...


2

Fig: Structure of fungus
...

1
...
It is an essential
component of fungal cell
...

Composition:
• Carbohydrate (80%): Chitin, chitosan, glucan and mannan
...

• Glycoprotein (10%)
...

2
...

4
...

It gives rigidity and strength to the cell
...

It takes part in reproduction
...

2
...

Composition: Phospholipid bilayer incorporated with ergosterol and cholesterol
...
It protects cytoplasm
...
Transport of materials to and from the cell
...
Synthesis of the cell wall
...
So antifungal drugs selectively inhibit
the fungal cell by acting on ergosterol
...
Cytoplasm: It contains mitochondria, 80s ribosome (60s+40s), endoplasmic reticulum, Golgi apparatus
and food storage vacuoles
...
Nucleus: It is eukaryotic with a nucleolus, nuclear membrane and linear chromosomes
...
Capsule: It is a non-essential structure situated outside the cell wall
...

Only one capsulated fungus is Cryptococcus neoformans
...

Significance of fungi
...
Drugs: Many fungi are major sources of pharmacologically active drugs
...

C
...

E
...

G
...
Antibiotics:
a
...

b
...

2
...
Immunosuppressant: Ciclosporin
...
Statins:
a
...
Lovastatin (from Penecillium terreus)
Cultured foods: Yeasts are used to make bread, alcoholic beverages
...
g
...
Agaricus bisporus is a commonly eaten species, used in salads, soups
...
Molds are used in cheese production
...

Bioremediation: Certain fungi, in particular, white rot fungi, can degrade insecticides, herbicides
and heavy fuels and turn them into CO2, water and basic elements
...

Mycorrhizae: The roots of about 90% of vascular plants form mycorrhizae, which are beneficial
associations between roots and fungi that assist the plants to absorb water and dissolved minerals
...
Mycoses: About 30% of known fungi species produce mycoses, which are fungal diseases of plants,
animals and humans
...

2
...

3
...

4
...

Classification of fungi: Fungi can be classified according to various traits such as
A
...

C
...


Morphological classification
Clinical classification
According to method of reproduction
On the basis of mode of nutrition

They are discussed below:
A
...
Yeast:
• Unicellular
• Reproduce by budding or binary fission
Example: Cryptococcus neoformans
...
Yeast like fungus:
• Partly yeast and partly hyphae
...

Example: Candida albicans
...
Molds:
• Multicellular
• Microscopic filaments known as hyphae
...

4

Example: Dermatophytes
...
Dimorphic fungi:
• Two forms (molds and yeasts) at different temperatures
...

B
...

1
...

Superficial fungal agents
Malassezia furfur
Hortaea werneckii
Piedraia hortae
Trichosporon species

Diseases
Pityriasis versicolor or tinea versicolor
Tinea nigra
Black piedra
White piedra

2
...
g
...

Cutaneous fungal agents
Dermatophytes
A
...

• T
...
tonsurans
• T
...
Epidermophyton spp
...
floccosum
C
...

• M
...
gypseum

Diseases
Ring worm / Tinea / Dermatophytosis

Candida species

Candidiasis
...
Sub-cutaneous fungi: They cause infections beneath the skin
...
Systemic or deep fungi: They cause infections that spread throughout the body
...
Opportunistic fungi: They infect immunocompromised patients like AIDS patients
...
According to method of reproduction:
1
...

• Basidiomycota form basidium
• Zogomycota form zygous
2
...
g
...
On the basis of mode of nutrition: Based on the mode of nutrition, fungi are classified into four
groups:
1
...
Parasites
3
...
Predacious fungi
They are discussed below:
1
...
These fungi live on dead
organic matter or exreta of both plant and animal origin
...

They are two types:
i
...

ii
...

2
...
Parasitic fungi are harmful
to the host and they produce disease condition in host organisms
...

Obligate parasites: These fungi can live only as parasite on a living host
...
Example: Puccinia which causes rust disease in several
crop plants including wheat
...

Facultative saprophytes: They are parasites but they can also survive on dead organic
matter in the absence of living host
...

iii
...
Under
certain conditions, they parasitize suitable plant hosts
...

3
...
Example: Lichens and mycorrhizae
...
Predacious fungi: They are animal capturing fungi (predators)
...

Examples are Arthrobotrys, Dactylella, Dactylaria
...

• They possess rapidly constricting hyphal traps which hold the captive for long time
...

• Some predacious fungi also produce sticky secretions for capturing nematodes
...
Cells
2
...
Reproduction

Yeasts

Molds

Unicellular
Multicellular
Spherical or elliptical
Microscopic filaments known as hyphae
Reproduce by budding or binary fission
...


Differences between bacteria and fungus:
1
...

3
...


Feature
Structure
Diameter
Nucleus
Cytoplasm

5
...
Cell wall content
7
...
Thermal dimorphism
9
...
Ribosome
11
...

Prokaryotic
Mitochondria and endoplasmic
reticulum are absent
...

Peptidoglycan
Endospores for survival, not for
reproduction
...

70s (50s + 30s)
Motile or non-motile

Multicellular
Approximately 4 µm
...

Sterols present
...

Yes (some)
Require organic carbon; no obligate
anaerobes
...

Non-motile
...
Asexual reproduction
1
...
Budding of somatic cell
3
...
Asexual spore formation
They are discussed below:
1
...

Process:
In binary fission a mature cell elongates and its nucleus divides into two daughter nuclei
↓
The daughter nuclei separates, cleaves cytoplasm centripetally in the middle till it divides parent
protoplasm into two daughter protoplasm
↓
A double cross wall is deposited in the middle to form two daughter cells
↓
Ultimately the middle layer of double cross wall degenerates and daughter cells are separated

7

Protoplasm: Nucleus + Cytoplasm
Cytoplasm is the liquid or fluid part of the protoplasm
...
Budding: Budding is the typical reproductive characteristic of Ascomycetes
...

↓
The parent nucleus also divides into two; once the daughter nucleus migrates into bud, the cytoplasm
of bud and mother remain continuous for some time
...
Then bud separates
and leads independent life
...
This gives branching
appearance
...
Fragmentation or disjoining of hyphae: In some fungi, fragmentation or disjoining of hyphae
occurs and each hyphae become a new organism
...
Asexual spore formation: Spore formation is the characteristic feature of fungi
...

Types of asexual spores:
SP Ar Coni Chlamydo কে Blast েরেরে
a
...
These cells are called arthroconidia
or arthrospores
...

b
...
These are usually formed during unfavourable conditions and are
8

thick walled single celled spore, which are highly resistant to adverse conditions
...
When favourable condition returns, each chlamydospore gives rise to a new
individual fungi
...

c
...
, sporangia) at a hyphal
tip, they are called sporangiospores e
...
Rhizopus
...
Conidiospores: If the spores are not enclosed in a sac but produced at the tip or sides of the
hypha, they are called conidiospores e
...
Penicillium, Aspergillus
...
Blastospores: Spores produced from a vegetative mother cell by budding are called
blastospores e
...
Zygomycetes, Ascomycetes, Basidiomycetes
...
Sexual reproduction: The process of sexual reproduction involves three phases:
o Plasmogamy: A haploid nucleus of a donor cell (+) penetrates the cytoplasm of a recipient
cell (⸺)
...

o Meiosis: The diploid nucleus gives rise to haploid nuclei (sexual spores), some of which may
be genetic recombinations
...
Sexual spores are fewer in number
than asexual spores
...
Zygospore: Zygospores are single large spores with thick walls
...

2
...
Example: Histoplasma, Microsporum
...
Basidiospore: Spores are formed externally on the tip of a pedestal called a basidium
...

9

Difference between bacterial spore and fungal spore:
1
...

3
...


Bacterial spore
They are produced in adverse environmental
condition as a protective mechanism
...

They are usually endospores
...


Zygomycota: Zygote forming fungi
Ascomycota: Sac fungi
Basidiomycota: Club fungi
Deuteromycota: Imperfect fungi

10

Fungal spore
1
...

2
...

3
...

4
...


Medically important fungi
Categories of fungal agents:
A
...

1
...
Coccidioides immitis
3
...
Blastomyces deramtitidis
B
...
They lack genes for patients that aid in
colonizing body tissues, though they can take advantage of some weakness in a host’s defense to
become established and cause disease
...
Serological tests are also useful but have little importance
...
Specimen collection: It depends upon the site of infection
...

• Aspirated pus
• Biopsy material
2
...
The specimen is
treated with 10% KOH to dissolve tissue material (keratin, epithelial cells, leukocytes, debris),
leaving the alkali resistant fungi intact
...

3
...
Bacterial growth is inhibited by SDA by low pH,
chloramphenicol and cycloheximide
...

4
...
A significant rise in the antibody titer must be observed
to confirm a diagnosis
...

neoformans in the CSF can be detected by the latex agglutination test
...
DNA probe test: DNA probe tests can be used for rapid diagnosis of fungi in the culture
...


11

Q
...

Serological tests are not reliable for the diagnosis of fungal diseases:
1
...

2
...
So serological tests (antibody
detection) are not reliable for the diagnosis of fungal diseases
...
Antibodies are important in case of deep fungi but not important for superficial fungi
...


12

Dermatophytes
Dermatophytes are a group of fungi which are keratinophilic and have the ability to infect the skin and skin
appendages e
...
hair and nail
...

2
...

4
...

Utilize keratin for metabolism
...

They cannot grow in serum
...
Trichophyton

2
...
Microsporum

•
•
•
•
•

Species or example
T
...
tonsurans
T
...
floccosum
M
...
gypseum

Site of infection
Skin, hair and nail

Skin and nail
Skin and hair

Mode of transmission of dermatophytes:
1
...
Human to human: They are transmitted by direct contact with infected persons through fomites,
such as contaminated towels, clothing, shared shower stalls and similar examples
...
Animal to human: Microsporum is also spread from animals such as dogs and cats
...
Typical ringworm lesions have an inflamed circular border containing papules and vesicles
surrounding a clear area of relatively normal skin
...
Erythema
3
...
Small nodules at the periphery
5
...
Heals by scar formation
7
...

Dermatophytes
1
...

3
...

5
...

7
...

• Ectothrix: When the spore of trichophyton remains
outside the hair shaft, then it is called ectothrix
...


13

Important:
•
•

Tinea is dermatophytic infection
...


Q
...
Trichophyton
2
...
Microsporum
Tinea pedis (Athlete’s foot)
This is a chronic dermatophytic infection of the toe webs
...

Site of infection: Foot (in between toes)
...

Agent:
1
...
T
...
Epidermophyton floccosum
Clinical features:
1
...

2
...

3
...

4
...

Laboratory diagnosis of dermatophyte infections:
Principle: Diagnosis is based on the demonstration of fugal structure on the specimen by microscopic
examination, and isolation and identification of fungus from culture
...
Specimen collection:
1
...
Nail clipping
3
...
Microscopic examination: The specimen is dissolved in KOH solution
...

• Nail: 40% KOH for at least 10 hours
...

Findings:
•
•

Skin and nail: Septate hyphae with arthrospores
...

C
...

Findings: Dermatophytes are identified by their colonial appearance and microscopic morphology
...

Texture: Cottony, powdery and velvety appearance
...

Macroconidia of Microsporum is spindle shaped
...


Microconidia:
•
•
•

Microconidia of T
...

Microconidia of T
...

Microconidia of T
...


Q
...
Diagnosis of Tinea infection?
KOH is a keratolytic agent which lyses the keratin present in skin, hair and nail and thus facilitates the
separation of fungal elements from skin, hair and nail tissues
...
Diagnosis of tinea infection to see the fungus clearly
...
furfur
Melassezia furfur is a dimorphic basidiomycete that is a normal member of the microbiota of the skin of
humans worldwide
...

Predisposing factors:
1
...
Increased sweating
3
...
Pytyriasis versicolor or Tinea versicolor: Pityriasis versicolor is a chronic mild superficial
infection of the stratum corneum caused by M
...

This condition typically occurs on the trunk, shoulders and arms, and rarely on the face and neck
...
Catheter associated sepsis
Stratum corneum: It is the outermost layer of epidermis, consisting of dead cells
...
Their cytoplasm shows filamentous
keratin
...
Lesions are hypopigmented areas, especially on tanned skin in the summer
...
Lesions usually occur on the chest, upper back, arms or abdomen
...
The lesions are chronic and occur as macular patches of discolored skin that may enlarge and
coalesce
...
Scaling, inflammation and irritation are minimal
...
Indeed, this common skin lesion is largely a cosmetic problem
...
Diagnosis:
Principle: It is based on demonstration of fungal structure in the specimen by microscopic examination after
dissolving the specimen in alkaline solution (NaOH or KOH)
...
Specimen: Skin scrapping
...
Microscopic examination:
A drop of 20% KOH in scrapping material is taken on a slide
↓
Covered with a cover slip
↓
The slide is slightly heated
↓
The slide is examined under microscope
...

C
...
But if needed, culture is done in Sabourad’s dextrose agar (SDA)
media at 22 – 250 C for 3 – 4 weeks
...


Treatment:
1
...

2
...


17

Histoplasma capsulatum
Histoplasma capsulatum is a systemic fungus that causes histoplasmosis
...
It is dimorphic fungus that exists as a mold in soil and as a yeast in tissue
...
It forms two types of asexual spores:
• Tuberculate Macroconidia with typical thick walls and fingerlike projections that are
important in laboratory identification
...

3
...

4
...

Transmission: Infection result from inhalation of the spores of dimorphic fungi
...

Pathogenicity/ Clinical manifestation/ Clinical features:
1
...
It is often seen in individuals with preexisting lung
disease
...

2
...

3
...
This syndrome, characterized by enlargement of the spleen and liver, can be
rapid, severe and fatal
...
Ocular histoplasmosis: It is a type I hypersensitivity reaction against Histoplasma in the eye
...

Pathogenesis:
Inhaled spores enter to the lungs
↓
Engulfed by macrophages
↓
Develop into yeast form in the lung
↓
Budding of yeast inside macrophages
↓
Yeasts survive within the macrophages by producing alkaline substances e
...
HCO3⸺, NH3
...

↓
Formation of granuloma in different organs
↓
Most infections remain asymptomatic and small granulomatous foci heal by calcification
...
g
...
g
...


18

Granuloma: A granuloma is a small area of inflammation that is found in many diseases
...
Granulomas form when the immune system attempts to wall off
substances it perceives as foreign but is unable to eliminate
...

2
...

4
...

Acute pulmonary form – symptoms like bacterial pneumonia
...


Laboratory diagnosis:
Principle: Diagnosis is based on demonstration of causative organism by microscopic examination of the
specimen, and isolation and identification of fungus from culture
...

Steps:
A
...
Sputum
2
...
Tissue biopsy
4
...
Bone marrow aspirates
6
...
Microscopic examination: Stained with fungal stains (e
...
periodic acid Schiff or calcofluor
white) or Giemsa stain
...
g
...

C
...
Complement fixation test (CFT): An antibody titer of 1:32 in the CFT with yeast phase
antigens is considered to be diagnostic
...
Immunodiffusion (ID): ID test is more specific but less sensitive than CFT
...
Detection of Histoplasma polysaccharide antigen by ELISA, Histoplasma RNA with DNA
probes are also useful
...
Skin test: The histoplasmin skin test becomes positive soon after infection and remains positive
for years
...


Treatment:
1
...

3
...

5
...

With progressive lung lesions, oral itraconazole is beneficial
...

In meningitis, fluconazole is often used because it penetrates the spinal fluid well
...


Prevention: There is no means of prevention except avoiding exposure in areas of endemic infection
...
Disease caused by candida is called candidiasis
...

Candida species:
1
...
Candida tropicalis
3
...

Morphology:
1
...

2
...

3
...

4
...


Pathological conditions or diseases or lesions caused by Candida albicans:
A
...
Oral thrush
2
...
It is seen mostly in moist sites e
...
axilla, groin etc
...
Nail lesions: Paronychia, onychomycosis
...
External ear: Otomycosis
...
Systemic candidiasis: Candidemia can be caused by indwelling catheters, surgery, intravenous drug
abuse, aspiration or damage of skin or GIT
...

1
...
Endocarditis
20

3
...
Esophagitis
C
...

Q
...

Candida albicans is a member of normal flora
...
Therefore, presence of it does not always indicate candidiasis
...
g
...
g
...
g
...
g
...
g
...

The predisposing factors for candidiasis are hereunder:
1
...

2
...

3
...

4
...
Traumatic: Burn, maceration
...
Others: Indwelling catheters
...
Why candidiasis occurs in prolonged use of broad spectrum antibiotics?
Broad spectrum antibiotics cause suppression of normal bacterial flora of skin and mucous membrane
...
albicans takes upper hand over normal bacterial flora and colonizes
...


Laboratory diagnosis of candidiasis:
Principle: Diagnosis is based on demonstration of causative agent by microscopic examination, and
isolation and identification by culture
...

Steps:
A
...

• Swabs from surface lesion
• Scraping from surface lesion
• Sputum
• Blood
• Spinal fluid
• Tissue biopsies
• Urine
• Exudates
21

• Material from removed intravenous catheters
B
...

• In case of other specimens: Wet film preparation with normal saline
...

C
...
It can also be cultured
in blood agar media
...

• Microscopic: Yeast with or without pseudohyphae
...
Germ tube test: C
...

• Germ tubes form in serum at 370 C, which serves to distinguish C
...

• Chlamydospores are typically formed by C
...

E
...

F
...

• Counter immune-electrophoresis
• Immune assay
...


22

Cryptococcus neoformans
Cryptococcus neoformans is an opportunistic fungal agent
...
C
...
It is the only
capsulated fungus
...
Round or oval in shape
...
It is not dimorphic i
...
no mold form
...
It forms a narrow based bud
...
There is no human to human transmission
...
Chronic localized infections: Well formed granuloma are typical
...
Chronic granulomatous cryptococcosis: Granulomata may be found in the lung, brain and
meninges
...
Pulmonary cryptococcosis: It is mostly seen in AIDS patients; may manifest as either massive
alveolar and interstitial or predominantly interstitial (intracapillary) infiltrates
...
Intraalveolar cryptococcosis: It may be associated with either an abundant macrophage reaction or
little to no inflammatory response with marked expansion of alveoli by proliferating organisms
...
Disseminated infection: There is minimal inflammation; although scattered macrophages are
present
...

Infection is initiated by inhalation of the yeast cells
...

↓
In immunocompromised patients, the yeasts may multiply and disseminate to other parts of the body but
preferentially to the CNS, causing cryptococcal meningitis
...

↓
The inflammatory reaction is usually minimal or granulomatous
...
Serological test is also helpful
...
Specimen collection:
• CSF – in case of cryptococcal meningitis
• Sputum
• Tissue
23

• Exudates
• Blood
• Cutaneous scrapings
• Urine
B
...

Findings: Round or oval yeast cell surrounded by wide unstained capsule
...
Culture: Culture is done in Sabouraud’s dextrose agar media at 370 C for 2 – 3 days
...

D
...
This test is the cryptococcal antigen test, often abbreviated as ‘crag’
...
Why india ink preparation is called negative stain?
India ink preparation is called negative stain as it stains whole fungus except the capsule
...

Prevention of cryptococcal meningitis: There is no specific means of prevention
...


Fungi that cause meningitis:
1
...
Candida albicans
3
...

2
...

4
...

They have separate hyphae that form V shaped branches
...

The conidia of Aspergillus form radiating chains
...
Infection of skin, eyes, ears and other organs
...
Fugal ball in the lungs
...
Allergic broncho-pulmonary aspergillosis
...


25

Agents causing mycetoma
Mycetoma: Mycetoma is a chronic granulomatous disease of subcutaneous tissue induced by traumatic
inoculation with any of several saprophytic species of fungi or actinomycetous bacteria that are normally
found in soil
...

Site: Foot, lower extrimities, hands and any exposed area
...
Actinomycetoma: It is a mycetoma caused by Actinomycetes (bacteria) including Actinomyces
israelii and N
...

2
...

The natural history and clinical features of both types of mycetoma are similar, but actimycetomas may be
more invasive, spreading from the subcutaneous tissue to the underlying muscle
...

↓
Multiply and produce localized chronic granuloma
...

↓
This process may spread to contiguous muscle and bone
↓
Untreated lesions persist for years and extend deeper and peripherally, causing deformation and loss of
function
...

Findings:
•
•

In case of fungus – septate hyphae
In case of bacteria – filamentous bacteria

26

Hortaea werneckii
Tinea nigra: Tinea nigra is a superficial chronic and asymptomatic infection of the serum corneum caused
by the Hortaea werneckii
...

Organism is transmitted during injury to the host
...

The lesions appear as a dark (brown to black) discoloration, often on the palm
...


Diagnosis: From above
...
g
...


27

Sample Questions and Answers
Q
...


By absorption: Fungi secrete catabolic enzymes outside their bodies to break large organic molecules into
smaller molecules, which they then transport throughout their bodies
...
Fungi that derive their nutrients
from living plants and animals usually have modified hyphae called haustoria
...
Parasitism: As parasites, fungi live in or on other organisms and get their nutrients from their hosts
...

3
...

4
...
In a mycorrhizal association, the fungus may colonize the roots of a host plant by either
growing directly into the root cells or by growing around the root cells
...

Q
...

Taxonomy: In biology, taxonomy is the science of naming, defining and classifying groups of biological organisms on
the basis of shared characteristics
...


2
...


Artificial system: It is based on the limited number of characteristics of living organisms and is used for
primary identification of living organisms
...

• Animals – aquatic, terrestrial and aerial
...
Organisms are classified into plant kingdom and animal kingdom
...
Animals are mobile and possess heterotrophic mode of nutrition
...

Phylogenic system: It is based on the evolution of life and shows the genetic relationships of organisms
...


Based on phylogenic system, the method of classification of living things includes 7 levels:
1
...

3
...

5
...

7
...

Monera
II
...

Fungi
IV
...

Animalia
Phylum: The phylum is the next level following kingdom in the classification of living things
...

Class: Class is a way to further divide organisms of a phylum
...
How will you diagnose cryptococcal meningitis in the laboratory?
Diagnosis of cryptococcal meningitis:
Principle: Diagnosis is based on the demonstration of fungal structure on the specimen by microscopic examination
and isolation and identification of fungus from culture
...
Specimen collection:
1
...
Serum
3
...
Microscopy: The use of India ink staining remains a common diagnostic tool for identifying Cryptococcus in
CSF
...
Culture: Culture is considered the gold standard for diagnosis of cryptococcal meningitis, but has several
disadvantages
...

• Cultures can also produce false negative results when the fungal burden is low, though diagnostic
yield can be improved using higher volumes of CSF
...
Antigen detection: The detection of cryptococcal antigen (CrAg) in CSF, serum or plasma has become an
essential diagnostic tool and should be performed on CSF for all patients with HIV with suspected meningitis
or any CNS symptoms
...
PCR: It is helpful but has not been widely developed given the high sensitivity, wide availability and low cost
of CrAg testing
...
Classify antifungal agents with examples
...

Classification of antifungal agents:
A
...
Alter cell membrane permeability:
• Azoles
• Polyenes

30

• Terbinafine
2
...
Block nucleic acid synthesis:
• Flucytosine
4
...
On the basis of site of action:
1
...

2
...

Griseofulvin: Griseofulvin is an antifungal medication used to treat a number of types of dermatophytoses
...
It is
taken by mouth
...
Sensitive dermatophytes take up the drug by an energy-dependent
mechanism and resistance can occur via decrease in this transport
...

Clinical uses: The oral formulation of the drug is indicated for dermatophytes of the skin and hair, but has been largely
replaced terbinafine and the azoles
...

2
...

4
...


Headaches
Mental confusion
Gastrointestinal irritation
Photosensitivity and
Changes in the liver function
...


Q
...
Although no worm is involved in the disease,
the name ringworm probably came from its ring shaped worm-like appearance
...
Write down the laboratory diagnosis of ringworm
...

Steps:
D
...
Skin scrapping
5
...
Hair plucking
E
...

The infection can appear at multiple body sites, and the severity of infection can range from mild lesions to
erythema multiforme, which is characterized by co-existing bacterial infections
...
Microscopic examination: The specimen is dissolved in KOH solution
...

• Nail: 40% KOH for at least 10 hours
...

Findings:
•
•

Skin and nail: Septate hyphae with arthrospores
...

G
...

Findings: Tinea corporis is identified by their colonial appearance and microscopic morphology
...
Wood lamp or UV light: Wood lamp or UV light is helpful in differentiating erythema caused by
Corynebacterium minutissimum (coal red fluorescent) from Tinea cruris (non-fluorescent)
...
The rash is made of spots that are
red welts, sometimes with purple or blistered areas in the center
...
]
Q
...

Madura foot: Madura foot is a chronic infection of the skin and underlying tissues caused by both bacteria
(actinomycotic mycetoma or actinomycetomas) and fungi (eumycetomas or mycotic mycetoma)
...

Causes:
1
...


Due to fungi (Eumycetes) – Eumycetoma (40%)
Due to bacteria (Actinomycetes) – Actinomycetoma (60%)

Pathogenesis:
Organisms enter through wounds from the soil
↓
Multiply and produce localized chronic granuloma
↓
Formation of subcutaneous nodules
↓
Formation of abscess
↓
Discharge of pus through sinuses
↓
Pus contains compact colored granules
↓
This process may spread to contiguous muscle and bone
↓
Untreated lesions persist for years and extend deeper and peripherally, causing deformation and loss of function
...
How can you diagnose Madura foot?
Laboratory diagnosis of Madura foot:
Principle: Diagnosis is based on the demonstration of fungal structure on the specimen by microscopic examination,
and isolation and identification of fungus from culture
...
Specimen collection: Pus
B
...

Finding:

32

•
•

In case of fungus: Septate hyphae
In case of bacteria: Filamentous bacteria

Short Notes
Aflatoxin
Aflatoxin: Aflatoxins are a type of mycotoxins produced by certain molds (Aspergillus flavus and Aspergillus paraciticus)
which grow in soil, decaying organisms, hay and grains
...

Major types and their metabolites: At least 14 different aflatoxins are produced in nature
...

1
...

3
...

5
...

Aflatoxin G1 and G2 are produced by some group II A
...
parasiticus
...

Aflatoxin M2 is the metabolite of aflatoxin B2 found in milk of cattle feed or contaminated foods
...


Toxicity range:
Aflatoxin B1 is considered the most toxic, capable of causing health problems such as liver disease or cancer,
autoimmune responses, digestive issues and in rare cases even death
...

Process of contamination: There are two ways that aflatoxin contamination usually occurs
...

Signs and symptoms: Some of the symptoms that aflatoxin exposure can cause include1
...

3
...

5
...

7
...


Techniques to avoid and lower the risk for symptoms:
1
...


Making change to diet: aflatoxin enters the body through certain widely available foods, including grains and
legumes
...

Taking detoxifying supplements: This will help body detoxify itself of aflatoxin and raise immunity against
its effects
...


Aflatoxin molds are entirely killed off even when corn, grains, peanuts or other foods are processed or roasted
...
9% and 81
...
However, this isn’t exactly a great solution because high
heat has the ability to alter nutrients found in legumes, destroy vitamins and turn them rancid
...
This is a
rapid test for the presumptive identification of C
...

Principle: Germ tubes are short outgrowth, non-separate germinating hyphae
...

Formation of germ tube is associated with increased synthesis of protein and ribonucleic acid
...
Germ tube is one of the
virulence factors of Candida albicans
...
5 ml of human serum
↓
Incubation at 370 C for 2-4 hours
↓
Examination under light microscope
↓
Tube like outgrowth of yeasts are found (germ tube)
Result:
Positive test: A short hyphal (filamentous) extension arising laterally from a yeast cell, with no constriction at the
point of origin
...

Negative test: No hyphal (filamentous) extension arising from a yeast cell or a short hyphal extension
...

2
...

Too heavy inoculum will inhibit germ tube formation
...
This is called oral thrush
...

Predisposing factors:
7
...

8
...

9
...

10
...
Traumatic: Burn, maceration
...
Others: Indwelling catheters
...
Germ test is also helpful
...
Specimen collection: Oral swab
...
Microscopic examination:
• In case of skin or nail scrapings: Preparation of film by dissolving with 10% KOH and calcofluor
white
...

Findings: Budding yeasts and pseudohyphae
...


Isolation and identification from culture:
Culture is done in Saboudaud’s dextrose agar media at 37 0 C for 24 – 48 hours
...

Findings:

• Naked eye: Cream colored colony with 48 hours
...


AIDS patients with a low CD4+ count and people receiving chemotherapy
...

Very low birth weight infants to prevent invasive fungal infections
...


Adverse effects:
1
...

3
...


Hypersensitivity reactions, including Stevens – Johnson syndrome in some cases
...

Diarrhea
Abdominal pain

Conidia
Conidia are asexual, non-motile spores of fungus
...

2
...

4
...

They are generated through the cellular process of mitosis
...

The morphology of specialized conidiophores is often distinctive of a specific species and can therefore be
used in identification of the species
...
Example: Candida albicans
...

Process:
The cell wall bulge out and softens in the area probably by certain enzymes brought by vesicles

37

↓
The protoplasm also bulge out in this region as small protuberance
...

↓
As the bud enlarges, a septum is laid down at the joining of bud with mother cell
...

↓
Sometimes, bud starts reproducing while still attached with mother cells
...


Importance: They cause a majority of mycoses in individuals e
...
Candida albicans
...
albicans are as follows:
D
...
Oral thrush
4
...
It
is seen mostly in moist sites e
...
axilla, groin etc
...
Nail lesions: Paronychia, onychomycosis
...
External ear: Otomycosis
...
Systemic candidiasis: Candidemia can be caused by indwelling catheters, surgery, intravenous drug abuse,
aspiration or damage of skin or GIT
...

5
...
Endocarditis
7
...
Esophagitis
F
...


Onychomycosis
Onychomycosis, also known as tinea unguinum is a fungal infection of the nail
...
Older people are more frequently affected
...

Symptoms:
1
...

3
...

5
...

Separation of the nail from the nail bed
If left untreated, the skin underneath and around the nail can become inflamed and painful
...

2
...

2
...

4
...


Aging is the most common risk factor for onychomycosis due to diminished blood circulation, longer exposure
to fungi and nails, which grow more slowly and thicken, increasing susceptibility to infection
...

Psoriasis
Athlete’s foot
Minor skin or nail injury

Diagnosis: Diagnosis is generally suspected based on the appearance and confirmed by laboratory testing
...

2
...

4
...

2
...
g
...


Ergot alkaloids
The ergot alkaloids are mycotoxins produced by several species of fungi in the genus of Claviceps
...
Ergot poising in humans and domestic animals
in known as er

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