Introduction Classification Pathogenesis Clinical types Lab diagnosis Prevention

1. ANKUR VASHISHTHA
SUBHARTI UNIVERSITY
MEERUT

2. LessonPlan
 Introduction
 Classification
 Pathogenesis
 Clinical types
 Lab diagnosis
 Prevention

3. DERMATOPHYTOSES
Dermatophytoses (tinea or ringworm) is the most common
superficial mycosis affecting skin, hair, and nails.
These are closely related keratinophilic fungi, which are capable to
invade keratinized tissues of skin and its appendages and are
correctively known as Dermatophytes.

4. Characteristicsof dermatophytes
 Filamentous fungi, digest keratin.
 Does not invade living tissues. They are incapable of
penetrating subcutaneous tissue.

5. Morphologicalclassification
 Dermatophytes are hyaline septate molds with more than hundred species described.
 These are divided into three main anamorphic genera depending on their morphological
characteristics, according to shape and site infections.
1. Trichophyton:- pencil shaped, infect skin, hair, nails (24 species)
 T. rubrum
 T. mentagrophytes
 T. schoenleinii
 T. tonsurans
 T. violaceum

6. Morphologicalclassification
2. Microsporum:- spindle
shaped, infect skin and hair. (16
species)
M. audouinii
M. canis
M. equinum
M. gypseum
3. Epidermophyton:-
Club shaped, infect
skin and nails. (2
species)
 E. floccosum
 E. stockdaleae

7. Ecologicalclassification
 Depending on the usual habitat (Humans, animals, and soil).
1. Anthrophilic :- infected Humans.
2. Zoophilic :- infect animals as well as birds.
3. Geophilic :- frequently isolated from soil.

8. Classificationofdermatophytesbasedontheirusualhabitat
Habitat Trichophyton Microsporum Epidermophyton
Anthropophilic  T. rubrum
 T. mentagrophytes
 T. schoenleinii
 T. tonsurans
 T. violaceum
 M. audouinii  E. floccosum
Zoophilic  T.equinum
 T.verrucosum
 M. canis
 M. equinum
Geophilic  T.ajelloi  M. gypseum  E. stockdaleae

9. PATHOGENESIS
Mode of infection:- Acquired by direct contact with soil, animals or humans infected with fungal
spores.
Predisposing factors – moist humid skin and tight ill – fitting underclothing.
◦ Skin: grow in a centrifugal pattern in the stratum corneum annular or ring-shaped pruritic
scaly skin lesions with central clearing and raised edges.
◦ Nails: invade nails through lateral or superficial nail plates and then spread throughout the
nails.
◦ Hair shaft: invade the hair shaft or may be found surrounding it. Hairs become brittle and
areas of alopecia may appear.
*Males more commonly infected as progesterone is inhibitory to dermatophyte growth.

10. PATHOGENESIS
Incubation period:- 1 to 2 weeks.
Anthropophilic dermatophytes:- commonest, cause relatively mild and chronic lesions but
respond poorly to treatment.
Geophilic and zoophilic species:- less adapted to human, produce more acute inflammatory
response and severe infections; but they tend to resolve more quickly.

11. CLINICAL types of dermatophytoses
• Tinea capitis
• Tinea corporis
• Tinea pedis (Athlete foot)
• Tinea cruris (jock itch)
• Tinea barbae
• Tinea faciei
• Tinea imbricate
• Tinea unguium (nail plate infection)
• Tinea manuum

12. CLINICAL types
TINEA CAPITIS
Infection of the scalp. (various types)
Kerion:- Painful inflammatory reaction producing
boggy lesions on scalp
Favus:- Cup like crust (scutula) forms around the
infected hair follicle with minimle hair shaft
involvement
Ectothrix:- Arthrospore formation occurs on the
surface of hair shaft
Endothrix:- Arthrospore formation occurs within
the hair completely filling hair shaft.
TINEA CORPORIS
Infection of the non hairy skin of the body
(trunk and limbs)

13. CLINICALtypes
TINEA PEDIS (ATHLETE FOOT)
 Infect first the webs between the toes, then spread
to the sole in a “moccasin” pattern.
TINEA CRURIS (JOCK ITCH)
 Infection of the groin area

14. CLINICAL types
TINEA BARBAE
 Infection of the beard and moustache area of
face
TINEA FACIE
 Infection of the non-bearded area of face

15. CLINICAL types
TINEA IMBRICATE
 Concentric lesions of the
skin
TINEA UNGUIUM (NAIL
PLATE INFECTION)
 Infection of nail beds
TINEA MANUUM
 Infection of the palmar aspect
of hands

16. ID reaction
 Id reaction is secondary eruption occurring in sensitized
tinea patients because of circulation of allergenic products
from primary site of infection.
 Frequently found in patients with absence of delayed
reaction to dermatophytic antigens (i.e. trichophytin).
 Two main types of id reaction:-
1. Lichen scrofulosorum-like:- commonly associated
with tinea capitis in children.
2. Pompholyx-like:- lesions are frequently found on
sides and flexor aspects of fingers and palms in
patients with tinea pedis.

17. Laboratorydiagnosis
Woods Lamps Examination:-
 Positive for various Microsporum species & Trichophyton schoenleinii.
 Fluorescence is due to the presence of pteridine pigment in cell wall.
Fluorescence seen under wood’s lamp
Microorganism Fluorescence Color
Microsporum audouinii Bright – green
Microsporum canis Bright – green
Microsporum ferrugineum Blue – green
Microsporum distortum Blue – green
Microsporum gypseum Dull – yellow
Trichophyton schoenleinii Dull – green
Malassezia furfur Golden – yellow

18. Laboratorydiagnosis
1.) Skin scraping 2.) Hair plucks
3.) Nail clipping from the
active margin of the lesions.
Specimen Collection:-

19. Transportationofspecimen
Transportation:- Moisture free paper
* When scrapings are to be sent through post, they should be folded in thick black paper.

20. DirectExamination
KOH mount :- branching septate hyaline mycelia, which frequently show arthrospore production.
Hair- arthroconidia on the surface of shaft (ectothrix) or within the shaft (endothrix).
Septate hyaline hyphae and arthospores of dermatophytes

21. Culture
Medium- Sabouraud dextrose agar (SDA) containing cycloheximide and incubated at 25°C,
30°C and 37°C for 4 weeks.
Potato dextrose agar – better sporulation (useful for the production of pigment).
* Colonies appear in 10 days to 3 weeks, depending on the organism.
Dermatophytes test Medium (DTM):- used for presumptive identification of dermatophytes
from fungal or bacterial contaminants found prevalent in cutaneous lesions. Incubation at 25°C.

22. Identification
Macroscopic appearance of the colonies:-
◦ Rate of growth
◦ Texture
◦ Pigmentation
◦ Colony topography

23. Colonymorphologyofdermatophytes
A. Trichophytpon Species, B. Microsporum species, C. Epidermophyton species
Macroscopic (colony) appearance of various dermatophytes on SDA.
A b c

24. Microscopicidentification
Microscopic appearance:- the colony are teased and LPCB mount is made to demonstrate the
hyphae and spore ( conidia).
◦ Conidia:- two types
◦ Microconidia :- small unicellular
◦ Macroconidia:- Multicellular, septate
◦ Special hyphae:- hyphae such as spiral hyphae, racquet hyphae and favic chandeliers.

25. DistributionofconidiaofDermatophytes
Dermatophytes Macroconidia Microconidia
Trichophyton Rare, thin – walled, smooth Abundant
Microsporum Numerous, thick – walled, rough Rare
Epidermophyton Numerous, smooth – walled Absent

26. LPCBteasemounts
A. Trichophytpon Species, B. Microsporum Species, C. Epidermophyton Species
Microscopic appearance of various dermatophytes species (LPCB mount).
b cA

27. MORPHOLOGICALCHARACTERSTICS
Dermatophytes Colony morphology Microscopic morphology
T. rubrum Velvety, red pigment on reverse Tear-drop microconidia, pencil-shaped
macroconidia
T. mentagrophytes White to tan, cottony or powdery, pigment
variable
Clusters of microconidia cigar-shaped
Microconidia with terminal rat-tail filament
T. schoenleinii Smooth, waxy, brownish Hyphal swellings, chlamydospores, favic
chandelier
T. violaceum Very slow growing, waxy, violet to purple
pigment
Distorted hyphae, conidia rare
M. audouinii Velvety, brownish, slow growning Thick-walled chlamydospores, conidia rare
and irregular

28. MORPHOLOGICALCHARACTERSTICS
Dermatophytes Colony morphology Microscopic morphology
M. canis Cottony, orange pigment on reverse Abudant, thick-walled spindle-shaped
macroconidia with up to 15 septa
M.Gypseum Powdery, buff-colored Abudant, thin-walled macroconidia with
4-6 septa
E.floccosum Yellowish-green, powdery Club-shaped macroconidia in clustrs

29. Biochemicaltest
Urease test:- Trichophyton mentagrophytes is
urease positive
Urease PositiveUrease Negative

30. Othermethodsofdiagnosis
Hair perforation test:- fungi pierce hair producing wedge – shaped perforations.
Positive:- Trichophyton mentagrophytes and Microsporum canis.

31. Othermethodsofdiagnosis
Molecular methods:- PCR
Skin test:- detects hypersensitivity to trichophytin

32. Treatment
Oral terbinafine or itraconazole are the drug of choice for treatment of dermatophytosis.
Duration:- depends on the affected site (1 – 2 weeks for skin lesions, 6 weeks for hair infection,
3 months for onychomycosis)
They can be given as pulse therapy.
Alternative:- oral griseofulvin and ketoconazole
Topical lotion:- whitfield ointment or tolnaftate

33. References
 Textbook of Medical Mycology, Jagdish Chander.
 Essentials of Medical Microbiology, Apurba Sankar Sastry.