This document provides an overview of mycology, which is the study of fungi. It discusses the classification, morphology, and types of fungal infections that affect the skin, nails, hair (dermatophytes), subcutaneous tissues, and internal organs/systems (systemic and opportunistic fungi). Common fungal infections discussed include dermatophytosis, tinea versicolor, tinea nigra, sporotrichosis, chromomycosis, mycetoma, blastomycosis, histoplasmosis, and coccidioidomycosis. The document also covers the laboratory diagnosis and treatment of various mycoses. The lecture objectives are to describe the classification of fungal infections,

1. MYCOLOGY
Dr. Fatima Fasih
Pathology Department
DUHS

2. 1. Introduction and Classification of fungal
infections (mycoses)
2. Types of Cutaneous & Subcutaneous
mycoses
3. Characteristic of cutaneous & subcutaneous
mycoses
4. Types of systemic and opportunistic mycoses
5. Lab diagnosis
6. Treatment
Lecture Objectives

3. Greek word(mykes) meaning mushroom.
Early 19th century- First documented animal
infection by any fungus was made by
Bassi.
1910-Raymond Sabourad –Published book
(Les Teigens)
 Comprehensive study of
dermatophytic organism in various field
of life.
Mycology

4.  Decomposition
 Biosynthetic factories
 Source of antibiotic
 Model organism – study biochemical
and genetic studies- Neurospora crassa
 Use in Recombinant DNA technology-
Saccharomyces cerviciae.
Benefical effects of Fungi

5.  Destruction of food,paper and cloth
 Animal and human diseases
 Plant disease
 Spoilage of agriculture produce
Harmful effects of Fungi

6. Introduction

7. Classification of Fungi
Based on
sexual
reproduction
Ascomycetes
Basidiomycete
s
Deuteromycete
s
Zygomycetes

8. Based on morphology
Yeast
Mould Yeast like Dimorphic
Mould(Molds) : Filamentous fungi e.g Aspergillus spps,Trichophyton rubrum
Yeast: Singled celled cells that buds e.g Crytococcus neoformans
,Saccharmyces cerviciae
Yeast Like: Similar to yeast but produce pseudohyphae E.g Candida
albicans
Dimorphic: Fungi existing in two different morphological forms at two
different environmental conditions. They exist as yeast in tissue and in vitro at
37 C and as moulds in their natural habitat and in vitro at room temperature.
e.G Histoplasma capsulatum, Blastomyces dermatiditis,Paracoccidiodes.

9.  The thallus of mould is made of hyphae.
 Hyphae- cylindrical tube like structure.
 Mycelium- mass of hyphae is known as
mycelium.
 Presence of hyphae – filamentous
nature of mould.
Mould

11. Types of mycelium
Aerial
Vegetative Fertile
 penetrates the
surface of the
medium and
absorbs
nutrients
grow above the
agar surface
Aerial hyphae that
bear reproductive
structures such as
conidia and
sporandia

12.  Spiral Hyphae:
 Trichophyton mentagrophytes
 Pectinate body:
 short,unilaterial projections from the
hyphae that resemble a broken comb
Type of Hyphae

13.  Favic chandelier; group of hyphae tips
that resembles antlers of the deer.
 Trichophyton schoenleninii,
Trichophytonviolaceum

14. Nodular organ : Enlargement in the
mycelium –consist of twisted hyphae.
Trichophyton mentagrophytes
Microsporum canis
Racquet hyphae: regular enlargment of
one end of each segement with the
opposing end remaning thin.
Epidermophyton floccosum.

15. Rhizoids
Root like structure
Seen in vegetative hyphae in some
members in zygomycetes.

16. Prolonged antibiotic therapy
Underlying disease HIV infection,
cancer,diabetes
Immunosuppressantagents&
chemotherapy,indwellingcatheters,drug
addiction
Age, obesity, transplant,
occupation
Predisposing
factors

17. Pathogenesis of Fungal
diseases
 Except for few fungi such as dimorphic fungi
that cause systemic mycoses and which are
dermatophytes which are primary pathogens.
 Rest are only opportunistic pathogens.
 Reason
 Human – hostile enviroment
 Great resistance to fungal infection.
 Fungi: saprophytic
 Enzymetic pathways function –efficiently-at
redox potential of non living substrates.

18.  Compared to reduced state of living
metabolizing tissue.
 Candida and Malasezzia have adapted to
human environment and exist as
commensals.

19. Complex interplay
Virulent
factors
Host defense
factors
Fungal
infection-
disease

20. Virulent factors
cell wall
glycoprotein
• Adhesin to
host cell.
capsule
• resist
phagocytosi
s
cytotoxin
• E.G
Candida
albicans
• GM-CSF
• Suppress
the
production
of
complement

21. Secreting
enzyme
• Keratinase
• Collagenase
• elastase
mycotoxins Thermal
dimorphism

22. Host defense factors
 Physical barriers – skin, mucus membrane
 Fatty acid content of skin
 pH of the skin, mucosal membrane and body
fluids.
 Normal flora.
 Chemical barriers: secretions, serum factors
 Natural Effector Cells- polymorphonuclear
leucocytes.
 Professional Phagocytes – monocytes and
macrophages

23. 1. Cutaneous
2. Subcutaneous
3. Systemic
4. Opportunistic
Classification based on
location

24.  Dermatophytoses
 Tinea Versicolor
 Tinea Nigra
Cutaneous mycoses

25. • A fungus that cause infections of skin, hair &
nails due to their ability to obtain nutrients from
keratinized material.
• Acquired due to contact with soil, infected
animal / human
• They colonize the keratin tissues & cause
inflammation in response to metabolic by-
products
Dermatophytoses
Caused by dermatophytes

26. Classified into 3 genera
1. Epidermophyton
2. Trichophyton
3. Microsporum
Dermatophytes

27.  Infect superficial keratinized structures
Skin, hair & nails
 Spread by direct contact with infected
person / animal e.g. dogs & cats
Characteristics of dermatophytic
infection

28.  Chronic infection
 Occur in warm, humid areas of body
e.g. foot, groin
Dermatophytoses (Tinea/ ring worm)

29. Inflamed circular border  Containing papules &
vesicles surrounding  Clear area of normal
skin,having broken hair & thickened nails
Characteristic of typical ring worm

30. Typical ring worm infection

31.  Tinea capitis (head)
 Tinea corporis (body)
 Tinea cruris (groin)
 Tinea pedis (foot)
Dermatophytoses a/c body site

32. Tinea capitis

33. Tinea corporis

34. Tinea pedis

35.  Trichophyton tonsurans
 Trichophyton rubrum
 Trichophyton schoenleinii
Types of Tinea Capitis

36.  Most common cause of Tinea capitis in
children
 Main cause of endothrix ( hair infection )
Trichophyton tonsurans

37.  Hypersensitivity reaction
 In response to fungal antigens
 Vesicles on fingers
 Skin test positive in pts with tinea
infection
Dermatophytid reaction

38.  10% KOH preparation & microscopic
examination of skin scrapping & nail
 Fungal culture on Sabouraud’s agar
 Tinea lesions caused by Microsporum sp.
become fluorescent when exposed to ultraviolet
light by wood lamp.
Lab diagnosis

39. Sabouraud’s agar

40.  Local antifungal cream like
Undecylenic acid
Miconazole
Tolnaftate
 Oral antifungal drug like
Griseofulvin
Treatment

41. Keep skin dry & cool
Prevention

42.  Caused by Malassezia furfur
 Superficial skin infection
 Cosmetic importance
Tinea versicolor

43.  Lesions appear as hypopigmented
areas
 Frequent in humid & hot weather
 Occur most commonly on tanned skin
 Associated with scaling of skin &
itching
Tinea Versicolor
Main characteristics

44. KOH preparation of skin scrapping
Lab diagnosis

45.  Topical Miconazole
 Lesion may recur
 Difficult to have permanent cure
Treatment

46. Tinea Versicolor

47.  Infection of keratinized layer of skin
 Causative organism, Cladosporium
werneckii
Tinea nigra

48.  Appear as brownish spot
 Due to melanin like pigment in hyphae
Tinea Nigra
Main characteristic

49. Tinea nigra

50.  Topical keratolytic agent
Salicylic acid
Treatment

51.  Fungi enter traumatic subcutaneous tissue
 Caused by fungi that grow in soil & on
vegetation
Subcutaneous Mycoses

52.  Sporotrichosis
 Chromomycosis
 Mycetoma
Types of subcutaneous mycoses

53.  Causative organism : Sporothrix schenckii
 Dimorphic fungus, lives on vegetation
 Occur most commonly in gardeners.
 Introduced into skin by a thorn, causing
pustule/ulcer
Sporotrichosis

54. Sporotrichosis

55.  Topical antifungal ointment for skin lesion
Itraconazole
Treatment

56. Protecting skin while touching plants,
moss & wood
Prevention

57.  Appear as cigar shaped budding yeast
in tissue specimen microscopy
 In culture hyphae are formed bearing
conidia resembling daisy
Lab diagnosis

58. Moss

59. • Wart like lesions
• Have crusting abscesses
• Common in tropics
• Lesion commonly found on bare feet &
legs
Chromomycosis
Characteristics

60.  Slowly progressive granulomatous infection
 Causative organism: Fonsecaea
Phialophora
Cladosporium
 Called Dematiaceous fungi, b/c of gray or black
color hyphae.
Chromomycosis

61. Chromomycosis

62. Dark brown & round fungal cells in
leukocytes seen on microscopy
Lab diagnosis

63. Oral flucytosine / Thiabendazole
Local surgery
Treatment

64.  Causative organism: Petriellidium , Madurella
 Produce abscesses & pus draining sinuses
 Common sites are hand & foot
Mycetoma

65. Mycetoma

66. No effective antifungal drug
Surgical excision is recommended
Treatment

67. Systemic infection
• Blastomycosis
• Histoplasmosis
• Coccidioidomycosis

68. Blastomycosis
It is a fungal infection, also known as
North American Blastomycosis caused
by the organism Blastomyces
dermatitidis.

69. Blastomyces dermatitidis is a dimorphic
fungus that exist as mold in soil and as a
yeast in tissue.
Blastomycosis

70. Transmission
• This fungus grows in moist soil rich in
organic material, forming hyphae with
small pear shaped conidia.
• Inhalation of the conidia causes human
infection
Blastomycosis

71. It can present in one of the following ways:
 A flu-like illness with fever, chills, myalgia, headache,
and a nonproductive cough which resolves within days.
An acute illness resembling bacterial pneumonia, with
symptoms of high fever, chills, a productive cough, and
pleuritic chest pain.
 A chronic illness that mimics tuberculosis or lung
cancer, with symptoms of low-grade fever, a productive
cough, night sweats, and weight loss.
Blastomycosis

72. • In tissue biopsy specimen, thick walled
yeast cells with single broad based buds
are seen microscopically.
• Hyphae with small pear shaped conidia
are visible on culture. The skin test lacks
specifically and has little value.
Laboratory diagnosis

73. • Itraconazole drug of choice for most patients.
• Amphotericin B used to treat severe disease
• Surgical excision may be helpful
• There is no means of prevention
Treatment & Prevention

74. It is a disease caused by the fungus
Histoplasma capsulatum.
It is a dimorphic fungus , exist as mold in
soil and as a yeast in tissue.
Form two types of asexual spores,
Tuberculate macroconidia, Microconidia
important in laboratory identification.
Histoplasmosis

75.  Histoplasmosis is contracted from contact to
soil, particularly if soil is heavily contaminated
with bird droppings.
 Birds are not infected, bats are infected and
can excrete the organism.
 Excavation of soil during construction or
exploration of bat infected caves has resulted
in significant number of infected individuals.
Transmission

76.  It primarily affects the lungs. Occasionally,
other organs are affected; this is called
disseminated histoplasmosis.
 It can be fatal if left untreated.
Histoplasmosis is common among AIDS
patients because of their suppressed immune
system
Histoplasmosis

77. Laboratory diagnosis
• In tissue biopsy specimens or bone
marrow aspirates, oval yeast cells
within macrophages are seen
microscopically.
• Culture on sabourad’s agar show
hyphae with tuberculate macroconidia.
• Serological test include complement
fixation, immunodiffusion
Histoplasmosis

78. No therapy is needed in asymptomatic or
mild primary infections.
In progressive lung lesions, oral
itraconazole is beneficial.
In disseminated disease, amphotericin B is
treatment of choice.
Treatment & prevention

79. It is a fungal disease caused by
Coccidioides immitis.
It is a dimorphic fungus that exist as mold in
soil and as a spherule in tissue
Coccidioidomycosis

80. Coccidioidomycosis
Transmission:
Infection is caused by inhalation of the
particles (arthrospores) swept into the air by
disruption of the soil, such as during
construction, farming, or an earthquake.
It is not transmitted from person to person.

81. • In lungs, arthrospores form spherules
that are large (30um in dia) have, doubly
refractive wall and filled with
endospores.
• Granulomatous lesion can occur in any
organ but primarily in bones and CNS
(meningitis)
Pathogenesis

82.  Some infected person have influenza
like illness with fever and cough.
 50% have changes in lungs ( infiltrates,
adenopathy, effusions) when seen on
chest x-ray.
 Disseminated disease can occur in
almost any organ esp. meninges, bone,
skin.
Clinical findings

83. Serious complications include severe
pneumonia, lung nodules, and disseminated
disease, where the fungus spreads throughout
the body
Coccidioidomycosis

84.  In tissue specimens, spherules seen
microscopically.
 Culture on Sabouraud’s agar incubated
at 25oC show hyphae with arthrospores.
Cultures are highly infectious.
Precautions against inhalation of
arthrospore should be taken.
Laboratory Diagnosis

85. • Amphotericin B or itraconazole is used
for persisting lung lesions or
disseminated disease.
• Patients recovered from coccidiodal
meningitis should receive long term
suppressive therapy with fluconazole to
prevent recurrence
Treatment & Prevention

86. Opportunistic mycosis
• Candidiasis
• Cryptococcosis
•Aspergillosis

87. Candidiasis
• It is a fungal infection (mycosis) of any of the
Candida species (all yeasts), of which Candida
albicans is the most common.
• It causes thrush, vaginitis, esophagitis, diaper
rash & chronic mucocutaneous candidiasis.

88. Properties
Candida albicans is an oval yeast with a
single bud. It is part of normal flora of
mucous membranes of
• Upper respiratory tract
• Gastrointestinal tract
• Female genital tract
•
Candidiasis

89. Presence of candida on skin predispose to
infections involving instruments that
penetrate skin such as needles and
indwelling catheter.
Skin invasion occur in warm, moist areas.
Transmission
Candidiasis

90. Candidiasis encompasses infections that range
from superficial, such as oral thrush & vaginitis, to
systemic and potentially life-threatening diseases.
Symptoms of candidiasis vary depending on the
area affected. Most candidial infections result in
minimal complications such as redness, itching
and discomfort
Candidiasis

92. Clinical findings
• Persons employed as dishwashers in
restaurants and institutions are
commonly affected.
• Thickening or loss of the nail can occur.
• Diaper rash in infants when wet diapers
are not changed promptly.
Candidiasis

93. In exudates or tissues, budding yeast and
pseudohyphae appear as gram positive and
can be visualized by using calcoflour white
staining.
In culture, yeast colonies resemble as large
staphylococcal colonies.
Germ tube test is used to differentiated C.
albicans from most other candida species.
Laboratory diagnosis

94. • Drug of choice for oropharyngeal or
esophageal thrush is fluconazole.
• Caspofungin or micafungin can also be use
for esophageal candidiasis.
• Skin infections can be treated by topical
antifungal drugs (clotrimazole or nystatin).
Treatment & Prevention

95. Aspergillosis
Aspergillosis is caused by a fungus
Aspergillus, which is commonly found growing
on dead leaves, stored grain, compost piles, or
in other decaying vegetation.

96. Infections caused by the fungus rarely occur in
people who have a normal immune system.
The rare infections caused by aspergillus
include pneumonia and fungus ball
(aspergilloma).
Aspergillosis

97. Laboratory diagnosis of fungal infections
Assignment # 1