SUPERFICIAL FUNGAL INFECTIONS Flashcards
Outline the 3 genera of Dermatophytic fungi causing tinea infections
Trichophyton
Microsporum
Epidermophyton
Why are dermatophtes restricted to the non viable skin?
because most are unable to grow at 37°C
or in the presence of sebum.
Which dermatophtes affects the hair?
Trichophyton and Microsporum
Which dermatophtes affects the nails?
Trichophyton and Epidermophyton
The inflammation caused by Dermatophytes is due to what?
Due to metabolic products of the fungus or to delayed hypersensitivity
How are ringworm infections transmitted?
by DIRECT CONTACT with materials (e.g. infected scales, hairs), animals, or soils
Classify Dermatophytes according to habitat
Zoophilic
Anthropophilic
Geophilic
Personal items e.g FOMITES
Outline the anthropophilic species
T. rubrum T. tonsurans T. violaceum T. schoenleinii M. Aoudouinii M. Ferrugineum Epidermophyton floccosum
Outline the zoophilic species
T. Mentagrophytea
T. Equinum
M. Canis
Outline the Geophilic specie
Microsporum gypseum
Dermatophyte have a worldwide distribution and reproduce asexually (T/F)
False.
Although they have a worldwide distribution, they reproduce sexually producing ASCOSPORE hence belong to the genus ARTHRODERMA
Tinea infections occur only in susceptible individuals (T/F)
True
Most dermatophytes initiate disease by their invasion of dead keratin with their branching, septate hyphae. (T/F)
False
It’s ALL Dermatophytes
Itemize 3 exogenous keratolytic enzymes produced by dermatophytes
Acid proteinases
elastase
keratinases
What is known as a Dermatophytid or Trichophytid?
A hypersensitivity reaction to a very active fungal infection due to the fungi itself or it’s products
What predisposes the host to chronic or recurrent dermatophyte infection?
the LACK OF OR A DEFECTIVE cell-mediated immunity/delayed hypersensitivity /inflamtory response
Describe in details what you expect to see on a KOH MOUNT preparation of a tinea infection
translucent branching, rod-shaped filaments (hyphae) of uniform width with lines of separation (septa) spanning the width and appearing at irregular intervals.
If the infection was actually due to candida what would you expect to see on KOH MOUNT preparation?
Elongated yeast forms(pseudohyphae) without true septations
What other investigations would you use to confirm the diagnosis of a tinea infection?
CULTURE
WOOD’S LIGHT EXAMINATION
Why is it important to do a culture? And name 2 types of agar used?
It’s used to identify the species of dermatophytes.
Mycosel agar
Sabouraud agar
All of the dermatophytes capable of invading hair will induce fluorescence (T/F)
False
Its only some
Mention the genus of Dermatophytes capable of being identified under Wood’s light?
Microsporum
Trichophyton
What colour do Microsporum and T. schoenleinni appear on wood’s light?
Microsporum - GREENISH YELLOW
T. schoenleinii - PALER GREEN
The wood’s light is an essential tool in the management of the patients in areas where favus infections are prevalent
True
And Microsporum too
Which zoophilic Dermatophypte commonly causes Tinea capitis?
Microsporum canis
Commonly found in cats and dogs
Itemize 3 factors that predispose children to Tinea capitis
Poor hygeine
Prolonged moist skin
Minor skin or scalp trauma
Which of the tinea infections may be seen as an epidemic
Tinea capitis
Ringworm infection of the body, trunk or extremities is called? And is commonly caused by what genus?
Tinea corporis
Trichophyton
Fungal infection of the feet/athlete’s foot is k no own as what? And what genus commonly causes this?
Tinea pedis
Epidermophyton floccosum
Trichophyton sp
What factors predispose individuals to Tinea pedis
Poor hygiene
Prolonged wearing of tennis shoes
Ringworm infections around the bearded area is know as
Tinea barbae
Ringworm infection of the face but not including infection of the bearded area is know as
Tinea faciei
Ringworm infection of the nail bed is known as? It’s otherwise called? What organism causes it?
Tinea unguium
Onychomycosis
Trichophyton spp
What age group are more predisposed to Tinea capitis
children between 3-7 years of age
What clinical signs accompany tinea capitis?
cervical or occipital lymphoadenopathy
alopecia
Itemize 5 clinical types of tinea capitis
Non-inflammatory black dot pattern Inflammatory tinea capitis(KERION) Seborrhoeic dermatitis like (GREY PATCH TYPE) Pustular type Favus
One or multiple inflamed boggy red tender areas of alopecia with pustules on and/or in surrounding skin.
KERION(honey-comb)
Mowed wheat field appearance of the scalp
Seborrhoeic dermatitis like(GREY PATCHY TYPE)
Extensive hair loss with atrophy, scarring and so called scutula
FAVUS
What does SCUTULA mean?
Yellow adherent crusts present on the scalp
What genus is commonly isolated from the “grey patch” type of tinea capitis
Microsporum canis
What genus is commonly isolated from the “black-dot” variant of tinea capitis?
Trichophyton tonsurans
What clinical type of tinea capitis results in SCARRING ALOPECIA if not treated promptly?
Inflammatory tinea capitis(KERION)
FAVUS
The rest can cause non-scarring alooecia
What clinical type of tinea capitis occurs without scaling or significant hair loss.
PUSTULAR TYPE
What investigations would you want to do in a suspected case of Tinea capitis?
WOOD’S LIGHTexamination of Plucked hair
DIRECT MICROSCOPY in 10% KOH WET MOUNTof scales and hair
CULTURE in sabouraud dextrose agar/mycosel agar
What component of sabouraud dextrose agar/mycosel agar suppress saprophyte and bacterial growth?
cycloheximide and chloramphenicol
Treatment options for Tinea capitis is not always systemic. (T/F)
False
It’s always systemic!
Outline the treatment options of tinea capitis?
GRISEOFULVIN
15-25 mg/kg/day for 2 months
FLUCONAZOLE (Diflucan)
8 mg/kg once weekly for 4-16 weeks.
TERBINAFINE(Lamisil)
20-40 kg body weight: 125 mg daily 2-4 weeks >40 kg body weight: 250 mg daily 2-4 weeks.
Outline 3 side effects of Griseofulvin
Headache
GI upset
Photosensitivity
It is well absorbed after fatty meal.
What differentiates tinea barbae and Tinea capitis from bacteria Folliculitis clinically?
Like tinea capitis, the hairs are always infected and easily removed while The hair in bacterial folliculitis resist removal (or painful on removal).
What are the primary lesions seen in tinea barbae?
Follicular PAPULES
PUSTLES
NODULES
What are the secondary lesions seen in tinea barbae?
KERION
CRUSTS
What is tinea barbae commonly mistaken for?
Staph Aureus folliculitis
Tinea facialis is otherwise known as?
Epidermal dermatophytosis
Are tinea barbae lesions painful or painless?
Painful
What is the treatment for tinea barbae?
Same as tinea capitis!
Tinea corporis affects glaborous and non glaborous areas of the skin (T/F)
False
Affects glaborous areas only
What other tinea presentations have been found to accompany tinea corporis?
Tinea manuum
Tinea pedis
What is the most common organism causing Tinea corporis and dermatophytosis world wide?
Trichophyton rubrum
What are the anthropophilic species causing tinea corporis
Trichophyton rubrum
Epidermophyton floccosum
What are the zoophilic specie causing tinea corporis
Microsporum canis
Trichophyton mentagrophyte