| What is cutaneous dermatophyte infection? | • Frequent reasons for consultation
• Dermatophytes: Filamentous fungi belonging to 3 genera: epidermophyton, microsporum and trichophyton
• Dermatophytes properties:
- are not saprophytes of the skin, mucous membranes or
integuments
- are always pathogenic
- are affine for keratin: horny layer of the epidermis and
integuments (hair, hair and nails)
- always respect the mucous membranes
- transmission by contact with contaminated hair or scales and adherence of fungal elements to the stratum corneum
• General triggering factor: epidermal lesion, whatever its nature (traumatic ...) |
| What are dermatophytes? | • Contamination by:
• Human: anthropophilic species (Trichophyton rubrum, interdigital T., T. violaceum, T. soudanenese, T. tonsurans ...)
• Contamination, direct or, most often, indirect by soils (dander) , combs, brushes, clothing, scarves hats. . . ; frequent contamination in sports (pool, gym), collective showers, school cloakroom; contamination favored by maceration (obese pleats, insufficient drying, closed or safety shoe, repeated contact with water ...); risk of epidemic in case of ringworm
• Animal (mammal): zoophile's species (Microsporum canis, T. mentagrophytes); transmission by wild animals or pets; not adapted to humans, these dermatophytes can induce inflammatory lesions
• Telluric: geophilic species (M. gypseum ...); transmission either directly from the ground (soil, sand) during a small lesion, or by a vector |
| What is tinea pedis? | • Tinea pedis (“athlete’s foot”) is the most common fungal
infection seen in developed countries Most commonly
caused by the fungus Trichophyton rubrum
• Fungus thrives in warm, moist environment (e.g., shoes)
• Public showers, gyms are common sources of infection
Good foot hygiene may reduce recurrences
• There are three clinical patterns of infection: interdigital,
moccasin, and vesiculobullous type
• Most common, presents with scaling and redness between the toes and may have associated maceration |
| What is Mocassin Type of tinea pedis? | • Also known as chronic hyperkeratotic type
• Sharply marginated scale, distributed along lateral borders of feet, heels, and soles
• Often associated with onychomycosis (fungal infection of the nails)
• Moccasin type may present as “one hand, two feet” syndrome
• Affected hand shows unilateral fine scaling in the creases
• If you see a hand like this, look at the feet as well |
| What is vesiculobollus type of tinea pedis? | • Grouped, 2-3 mm vesicles, often on the arch or instep
• May be itchy or painful
• Often scale on the sole
• Delayed hypersensitivity immune response to a dermatophyte, or ide reaction |
| What is KOH microscopic exam | • KOH microscopy is the easiest and most cost
effective method used to diagnose fungal
infections of the hair, skin, and nails
• KOH dissolves keratinocytes; easier to see
hyphae
• Proper technique requires training. Sensitivity
is dependent on the operator’s experience
• Heat may be used to accelerate this reaction |
| How is KOH exam done? | • Clean and moisten skin with alcohol swab
• Collect scale with #15 scalpel blade
• Put scale on center of glass slide
• Add drops of KOH and coverslip; heat slide gently or wait 10 minutes
• Microscopy: scan at 10X to locate hyphae; then study in detail at 40X if needed |
| What is tx of tinea pedis? | • For all types of tinea pedis, hygiene and
topical antifungals are effective therapies
• Hygiene: Dry the area after bathing
• Change socks daily and alternate shoes worn
• Consider wearing open shoes such as sandals
• Use antifungal foot powder to keep feet dry
• First-line therapy: imidazoles (fungistatic), clotrimazole or miconazole cream apply to affected areas twice daily for 4- 6 weeks
• Second-line therapy: allylamines (fungicidal), terbinafine, naftifine, or butenafine cream or gel once or twice daily (product dependent) for 4-6 weeks
• Allylamines have better sustained cure rates than
imidazoles but are often more expensive
• Prescribe 30-45 g to cover both soles twice daily for a
month |
| What is tinea corporis? | Tinea corporis, “ringworm”, refers to dermatophytosis of the skin, usually affecting the trunk and limbs
Often itchy
The margin of the lesion is the most active; central area tends to heal
Scrapings should be taken from the red scaly margin for KOH exam
A variant of this is tinea cruris or “jock itch”, which has a similar presentation but appears in the groin
Check the bottom of the feet for tinea pedis
• Annular lesion with central clearing is typical of tinea corporis |
| What is tinea cruris? | • Dermatophyte infection of the groin is called
tinea cruris (aka “jock itch”)
• May lack scale because of scrotal occlusion |
| What is fungal culture usage? | • Tinea corporis may be caused by different
fungal species with different environmental
sources Fungal culture can help identify the
source and guide treatment
• You may be able to submit skin scrapings in a
sterile specimen container and have the lab
plate it for you |
| How is tx of tinea corporis? | • Topical antifungals are applied until tinea shows resolution, then continue treatment for a minimum of two weeks; this usually takes 4-6 weeks total Imidazoles (clotrimazole, miconazole) are first- line
• Allylamines (naftifene, terbinafine, butenafine) are second-line unless cheaper at your institution than imidazoles
• Oral antifungals are indicated if: Poor response to topical agents, an animal is the suspected source of infection, or large surface area involved
• Fungal culture can help guide therapy
• Terbinafine daily for 7-14 days Check liver function tests if giving more than 7 days
• Discuss and monitor for side effects and drug interactions |
| What is fungal keratoderma palmoplantare? | • Typical feature: unilateral palmar keratoderma
occasionally pruriginous + bilateral plantar
keratoderma (syndrome one hand, two feet)
• Whitish, mealy, with strengthening of
palmoplantar folds
• May be accompanied by nail involvement
• Plantar keratoderma, fissure or not, limited or not
to the heel, isolated without palmar involvement
is possible |
| What are some key points in dermatophytes? | • Dermatophytosis: superficial cutaneous and nail
infection, frequent, due to dermatophytes, keratinophilic
filamentous fungi (horny layer of the epidermis, superficial
body growths), always pathogenic
• Never with mucosal involvement
• Dermatophytes are acquired by contamination either by
humans, either by the soil or by animals
• Moisture, local trauma, occlusion of folds,
immunosuppression, diabetes are contributing factors
• Clinical lesions are rounded, well limited, with an
erythematosquamous border, or vesiculo-pustular, of
centrifugal evolution with a clear center |
| What is onychomycosis? | • Onychomycosis is a chronic fungal infection of
the nail bed
• Usually starts with tinea pedis
• Response very poor to topical antifungals
• Most common type is distal subungual onychomycosis
Thickened nail, subungual fragments, and dissociation
of the nail plate from nail bed
• Usually caused by dermatophyte Trichophyton rubrum
• Superficial white onychomycosis (SWO) is less common
and may respond to topical therapy
• Proximal subungual onychomycosis (PSO) may herald
immunosuppression |
| How is confirmation of fungus done? | • Confirmation of fungus in the affected nail is necessary
before oral antifungal treatment May mimic other
conditions (e.g. psoriasis)
– Methods for confirming fungus: Fungal culture is
preferred because identification of organism can
help direct therapy
– KOH exam of fine curetting of subungual fragments
– Nail clippings or nail biopsy submitted for histologic
exam with fungal stains |
| What is distal subungual onychomycosis tx? | • 1st line treatment
• Terbinafine 250 mg daily for 12 weeks
– Risks: idiosyncratic hepatotoxicity, reversible taste
disturbance, drug interactions (P450 CYP2D6
inhibitor), skin reactions Must prevent patients on risks and
monitor liver function tests (LFT’s)
– Do not begin treatment without confirmation of
fungus on culture, KOH, or histologic exam
• Clinical cure only seen in 50% of patients, so
treatment failure is a significant risk
• 2nd line therapies Itraconazole, Fluconazole
• These may be helpful in lesions caused by nondermatophyte molds or yeast
• Obtain positive fungal culture to identify
organism before initiating second-line
therapies |
| What is tenia versicolor? | • Tinea versicolor (Pityriasis versicolor) is not
caused by a dermatophyte
• It is a colonization caused by species of
Malassezia, a lipophilic yeast that is a normal
resident in the keratin of the skin and hair
follicles of individuals at puberty and beyond
• Tends to recur annually in the summer months |
| What are characteristics of tenia versicolor? | •Characterized by welldemarcated, tan, salmon, or
hypopigmented or hyperpigmented patches, occurring most commonly on the trunk and arms
•Macules will grow, coalesce and various shapes and sizes are attained in an asymmetric distribution
•Visible scale is not often present, but when rubbed with a finger or scalpel blade, scale is readily seen. This is a diagnostic feature of tinea versicolor |
| What is 1st line tx of tenia versicolor? | 1. Shampoos: selenium sulfide 2% shampoo, ketoconazole
shampoo, zinc pyrithione shampoo
• Apply daily to affected areas, wait 10 minutes, then rinse
• Repeat daily for 1-4 weeks
• As effective as oral therapy
2. Imidazole creams: ketoconazole, clotrimazole
• Apply daily or bid for 1-4 weeks
• Very effective for limited areas
• Usually more expensive than shampoos due to surface area |
| What are oral tx of tenia versicolor? | • Oral medication may be used when topical therapy fails, if the benefits outweigh the risks or the patient has a strong
preference for oral therapy
• Oral medications of choice include: Fluconazole 300 mg / week for 2-4 weeks
• Itraconazole 200 mg /day for 7 days or 100 mg /day for 14 days
• Side effects: hepatotoxicity, drug-drug interactions,
gastrointestinal side effects, congestive heart failure, etc.
• Monitor liver function if giving more than 7 days |
| How is relapse of tenia? | • Many patients relapse
• If the patient has had more than one previous
episode, recommend maintenance therapy
• Maintenance therapy: topicals are used 1-
2x/week Ketoconazole shampoo, Selenium
sulfide (2.5%) lotion or shampoo, Zinc pyrithione
(bar or shampoo)
• Leave on for 10 minutes before rinsing off |
| What is intertigo? | • Intertrigo = inflammation of large skin folds
Inframammary fold, gluteal cleft, inguinal creases, and
folds under pannus (abdomen)
• Up to 10% of intertrigo is complicated by Candida yeast
colonization Classic symptom: burns more than itches
• Classic sign: satellite macules, papules, or pustules
around the erythema in the fold
• KOH exam may reveal pseudohyphae, but fungal
culture may be more sensitive than KOH for Candida |
| How is pathogensis of candida albicans? | • Mucosal endosaprophyte:
• Gastrointestinal tract + female genital mucosa
• Opportunistic pathogen under the influence of various contributing factors (secondary proliferation with imbalance of microbial mucous flora +++) is never present on healthy skin
• Triggering factors of cutaneous or mucosal candidiasis:
• optimum conditions for the development of C. albicans: heat, humidity, acidic pH, medium rich in sugar
• local factors : humidity; maceration (repeated contact with water, occlusion, obesity, sweating ...); acidic pH; chronic irritations (dental prosthesis, post-radiation mucositis ...); xerostomia; local factors of exogenous origin: pastry (repeated skin contact with sugar) |
| How is tx of candida albicans? | • General conditions:
• Terrain: (congenital immunosuppression, physiological: extreme age of life
and pregnancy,
• acquired: immunosuppressive treatments, corticosteroids, HIV, diabetes);
• Medicines: systemic antibiotics, oestroprogestatives (genital mucosal infections)
• Infection modalities:
• endogenous pathway mainly (+++): digestive or genital origin
• exogenous way, rarely: newborn: chorioamnionitis secondary to maternal candidal vaginitis (maternofetal transmission); adults: sexually transmitted candidiasis
• Septicemia or deep visceral lesions with C. albicans: exceptional (deep immunosuppression, bone marrow suppression, premature neonate) |
| How is prevention of candidan albicans? | • Prevention
– Keep intertriginous areas dry, clean, and
cool Dry areas after bathing with hair dryer on
cool setting; repeat twice daily
• Encourage weight loss for obese patients
• Wear loose clothing made of cotton |
| What is candida intertigo tx? | • Topical antifungal agents
– Imidazoles: miconazole, clotrimazole, econazole
More effective than nystatin, but cream formulations may
burn. Warn patients to expect this.
– Also treat dermatophytes in case you’re not sure
– Polyene: nystatin Only works for Candida, not
dermatophytes
– Has advantage of powder and ointment formulations
• Allylamines (terbinafine, naftifene) are not effective
for Candida yeast |
| How is use of anti inflammatory agents in candida? | • Topical anti-inflammatory
• Low strength corticosteroid preparations
rapidly improves the itching and burning
– Desonide ointment or 1% hydrocortisone
ointment twice daily for 1-2 weeks Ointments burn
less than creams when applying
– Longer use can cause steroid atrophy, so avoid
– Alternatively may use tacrolimus ointment 0.1%,
which does not cause atrophy |
| What are key points in cadida? | • Candidiasis: opportunistic infections with yeast fungi of the genus Candida, C. albicans is responsible for most pathological manifestations in humans
•Candida albicans: saprophyte of the digestive and genital mucosa. Passage of yeast to a pathogenic stage depending on local factors (moisture, acidity, sugar) and / or general (immunodepression / antibiotic therapy)
• Candida infections: mucous membranes ++, but C. albicans is still pathogenic when isolated , from a cutaneous lesion
• Diagnosis of candidiasis: clinical. Confirmation by mycological examination in atypical cases or in certain topographies
• The prophylaxis and treatment of candidiasis do not reduce to their only treatment locally or general. They must seek out triggering factors, particularly in the case of recurrent features |
