Superficial Fungal Infections Flashcards
Overview
Most superficial fungal infections caused by:
Dermatophytosis – superficial mycotic infections of the skin
Tinea is the latin word for fungus
● precedes the latin name for the body part that is infected (corporis
= body, pedis = foot, cruris=of the leg)
Dermatophytes survive on dead keratin (e.g., top layer of epidermis, hair,
nails. Do not invade living tissue
Most superficial fungal infections caused by:
● 3 genera of dermatophytes (Trichophyton, Epidermophyton,
Microsporum)
● Yeast-like fungi (e.g., Candida)
Transmission: Direct contact from infected people, fomites, the environment (soil) or
animals
Predisposing host factors:
● Moisture (occlusive clothing/shoes, warm humid climates)
● Genetic susceptibility
● Impaired immunity (e.g., diabetes, HIV, chemotherapy)
Tinea Pedis - Pathophysiology
Organisms:
Most commonly caused by dermatophytes
Yeast (Candida albicans) can also be involved
Gram-negative bacteria - ulcerative forms
Predisposing risk factors:
Host factors: immunosuppression, poorly controlled diabetes mellitus, obesity,
hyperhidrosis
Local factors: trauma, occluded skin, poor hygiene, moist conditions, contaminated
surface
Goals of Therapy
Prevalence:
Symptom relief
Cure infection
Prevent recurrence and transmission
● 70% will acquire Athlete’s foot infection at some point in their lifetime
● Males are 4 times more likely than females to acquire infection
● Prevalence increases with age
● Marathon runners have 30% prevalence rate
Transmission
Directly via contact with infected person
Indirectly – contaminated surfaces of warm moist
environments (e.g., swimming pools/decks, gym change
rooms)
● Fungus invades outermost layer of skin
● Drying and scaling initially (may be asymptomatic)
● Moisture and increased temperature by hot sweaty feet
promotes fungal growth
clinical presentation
chronic interdigital inf
moccasin-type inf
vesicular
ulcerative
see slide 11
Differential Diagnosis
Contact dermatitis, eczema, psoriasis or bacterial infections
When assessing patient, consider:
● Presenting signs and symptoms (?weeping & oozing, involvement of
toenail)
● Past medical history
● History of the present illness - ?risk factors
● Patient Age
Non-pharm
Mainly focused on prevention of recurrence and avoiding transmission.
● Avoid going barefoot in public spaces (direct contact with contaminated surface) -
sandals!
● Manage hyperhidrosis (antiperspirant or absorbent powders - talcum/aluminum
chloride);
● allow shoes to dry thoroughly
● avoid tight-fitting shoes
● Breathable shoes - leather/canvas allow feet to breathe
● Personal hygiene
● wash feet and dry feet thoroughly
● change socks daily (choose breathable sock materials, avoid nylon)
● launder items used by infected person often i.e don’t share towels)
Treatment
Topical: Typically used first line
Systemic: consider in patients with diabetes mellitus and
immunosuppression; moccasin type presentation (or patients who fail
topical therapy).
● Prior to starting oral therapy, presence of a dermatophyte should be
confirmed by microscopy & culture growth (refer these patients)
topical tx
slide 18
Allylamines, azoles, tolnaftate, undecylenic acid all more effective than placebo
Meta-analysis supports of allylamines (terbinafine) over azoles as drug of choice. Trial data suggests minimum treatment period is 2-4 weeks, for either allylamine or azole
terbinafine>miconazole/clotrimazole>tolnaftate
Recurrence is common and treatment failure occurs in ~30% of cases (often due to poor adherence)
● Need to assess potential cause of failure
No evidence that tea tree oil is effective
Individual preference
Ointments remain on skin longer but careful as can occlude and
cause maceration and slows skin healing (most topicals are
cream ie. Loprox, Lamisil, Monistat, Canesten, Ketoderm,
Tinactin)
● Solutions, sprays, foams applied directly to skin and let air dry
● Cost
Application & Treatment Duration
● Apply to clean dry area
● Affected area including 2-3 cm beyond the border
● Most products (e.g., creams, lotions etc) apply/massage into area twice
daily for at least 4 weeks (should be used for ~1 week after the
infection has cleared to prevent recurrent infection).
● Sprays/powders – apply to dry footwear and skin (check directions)
Monitoring
Efficacy:
● Finish recommended course of treatment to prevent reoccurrence, even though symptoms
may resolve before treatment is complete.
● Refer if worsens or no improvement after 2 weeks of treatment or not completely resolved
after 6 weeks of treatment
Safety:
Topical products: Local skin irritation or hypersensitivity (burning, erythema, pruritus, rash,
stinging). Rash suggests possible allergy to product - discontinue use and consult HCP
CPS: FUNGAL SKIN INFECTION - View Table 3: Overall monitoring Therapy for Fungal Skin
Infections
Systemic Therapy
allylamine
terbinafine
azoles
itraconazole (Sporonox)
fluconazole
Topical Corticosteroids
Some topical antifungal/corticosteroid combinations exist commercially:
Clotrimazole 1%/betamethasone dipropionate 0.05% (Lotriderm®)
Clioquinol 3%/flumethasone pivalate 0.02% (Locacorten Vioform®)
Clioquinol 3%/hydrocortisone 1% (Vioform HC®)
*However, their use is limited use due to reduced efficacy vs single-entity
antifungal agents and it is recommended to avoid. Increased costs and
potential side effects (ie. skin atrophy, immunosuppression from steroid
leading to enhanced fungal growth) must also be considered.
TINEA CRURIS (jock itch)
● Involves groin - medial and upper parts of the thigh and pubic
area, Occasionally anal cleft
● Unlike candida – penis and scrotum usually spared
● May also involve buttocks
Principal dermatophytes:
T. rubrum (most common)
T. mentagrophytes
E. floccosum
