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.
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)
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.
Mode of infection:- Acquired by direct contact with soil, animals or humans infected with fungal
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
◦ 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.
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.
12. CLINICAL types
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
Ectothrix:- Arthrospore formation occurs on the
surface of hair shaft
Endothrix:- Arthrospore formation occurs within
the hair completely filling hair shaft.
Infection of the non hairy skin of the body
(trunk and limbs)
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
15. CLINICAL types
Concentric lesions of the
TINEA UNGUIUM (NAIL
Infection of nail beds
Infection of the palmar aspect
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.
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
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
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.
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.
Dermatophytes Colony morphology Microscopic morphology
T. rubrum Velvety, red pigment on reverse Tear-drop microconidia, pencil-shaped
T. mentagrophytes White to tan, cottony or powdery, pigment
Clusters of microconidia cigar-shaped
Microconidia with terminal rat-tail filament
T. schoenleinii Smooth, waxy, brownish Hyphal swellings, chlamydospores, favic
T. violaceum Very slow growing, waxy, violet to purple
Distorted hyphae, conidia rare
M. audouinii Velvety, brownish, slow growning Thick-walled chlamydospores, conidia rare
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
E.floccosum Yellowish-green, powdery Club-shaped macroconidia in clustrs
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