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Tinea Pedis Natural History

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Athlete's foot is the layman's term and can be found in reference to any ... Mocassin type, keratotic feet. Diabetic. Immunosuppressed. Compromised circulation ... – PowerPoint PPT presentation

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Title: Tinea Pedis Natural History


1
Tinea PedisNatural HistoryClinical Trials
  • Joseph Porres, M.D., Ph.D.
  • Medical Officer, DDDDP

2
Part I Natural History
  • Tinea pedis subtypes
  • Causative organisms
  • Dermatomycosis syndrome
  • Predisposing factors
  • Complicating factors Complications
  • Epidemiology recurrence
  • Diagnosis
  • Treatment

3
Tinea Pedis Subtypes
  • Interdigital pruritus, erythema, scaling,
    fissuring, maceration
  • Plantar
  • Moccasin scaling, pruritus, erythema
  • Vesicobullous pruritus, vesicles, scaling,
    erythema
  • Combinations of interdigital and plantar
  • Athletes foot is the laymans term and can be
    found in reference to any of these forms

4
Causative Organisms
  • Trichophyton rubrum (60-80)
  • Plantar, mocassin
  • Plantar small vesicles, may also affect distal
    subungual nail, other body sites
  • Trichophyton mentagrophytes (10-20),
  • Peri-plantar large vesicles, and may spread to
    white superficial nail
  • Epidermophyton floccosum (3-10)

5
Tinea Pedis Interdigitalis
Dermatlas, JHMI.EDU
6
Tinea Pedis Plantaris
Rebell, G. Zaias, N. Cutis 2001, 67, 5S, 6-17
7
Tinea Pedis Plantaris, Vesicular
Dermatlas, JHMI.EDU
8
Tinea Pedis Plantaris, Moccasin
Rebell, G. Zaias, N. Cutis 2001, 67, 5S, 6-17
9
Rebell, G. Zaias, N. Cutis 2001, 67, 5S, 6-17
10
Predisposing Factors
  • Closed communities army barracks, boarding
    schools
  • Public baths, swimming pools
  • Local trauma on dermatophyte carrying
    individual
  • Occlusive footgear
  • Immersion
  • Warm weather
  • Exposure to hair of infected animals (rats in
    Vietnam)
  • Infected family members (17 in one study)
  • Familial predisposition

11
Complicating Factors
  • Immunosuppression
  • Atopy
  • Diabetes
  • Compromised circulation
  • Localized trauma
  • Geriatric population

12
Complications Cellulitis
  • Tinea pedis unrecognized
  • Treatment not given
  • Treatment is inadequate
  • Reinfection from the nail

13
Epidemiology
  • 15-70 of population at large
  • 40 of patients attending a general clinic
  • Those seeking help often have nail involvement
  • Many undiagnosed cases
  • Dermatophytes isolated from
  • 2-40 normal feet
  • Public showers
  • Swimming pools
  • Shoes and Socks

14
Recurrence
  • Topical terbinafine and clotrimazole in
    interdigital tinea pedis A multicenter
    comparison of cure and relapse rates with 1- and
    4- week treatment regimens.
  • Bergstresser PR et al, JAAD 1993 28 648-51
  • Long-term outcome of patients with interdigital
    tinea pedis treated with terbinafine or
    clotrimazole.
  • Elewski, B. et al. JAAD 1995 32290-2

15
Study Details
  • 193 evaluable patients with interdigital tinea
    pedis
  • Treatment twice daily with
  • terbinafine cr or clotrimazole cr
  • 1 or 4 weeks
  • Observation for up to 18 months Elewski
  • Mycology Cure

16
Study Results
17
Diagnosis
  • Clinical by clinical signs and symptoms
  • Mycology KOH (direct examination) and culture.
  • Mycology KOH helps confirm diagnosis and avoid
  • Delay of indicated treatment
  • Prescribing inappropriate treatment

18
Treatment. Efficacy rates reported
Treatment of Skin Disease. Lebohl, M. et al,
Mosby. 2003
19
Part II Clinical Trials
  • Dose ranging studies
  • Clinical trials for safety and efficacy


20
Dose Ranging Studies For Tinea Pedis
  • Dose ranging studies for topical antifungals
    often recommended by FDA but usually not
    conducted
  • Dose ranging studies for topical antifungals to
    select the best safety/efficacy dose
  • Drug strength
  • Frequency of application
  • Duration of treatment

21
Clinical Safety and Efficacy Trials
  • Assessment
  • Outcomes

22
Assessment
  • Mycology
  • Direct microscopic examination (KOH)
  • Mycology culture
  • Clinical. Signs and symptoms
  • Erythema
  • Scaling
  • Pruritus, etc.

23
Outcomes
  • Mycology Cure (MC)
  • Negative KOH and negative culture
  • Effective treatment
  • MC, no symptoms, only residual signs
  • Complete Cure
  • MC, and no signs or symptoms


24
Clinical Safety and Efficay Studies
  • Inclusion/exclusion criteria often do not mimic
    the populations expected to actually use the
    product
  • Include healthy patients with interdigital tinea
    pedis
  • Exclude harder cases
  • Onychomycosis
  • Mocassin type, keratotic feet
  • Diabetic
  • Immunosuppressed
  • Compromised circulation

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