Dermatophytoses

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Dermatophytoses
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Glenn S. Bulmer, Ph.D. Prof. Medical Mycology
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Classification of Mycoses

• Dermatophytoses
• - Superficial mycoses
• Systemic mycoses

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Synonyms - Dermatophytoses -
Dermatophytosis - Ringworms - Athletes foot -
Tinea body site, e.g., Tinea capitis, Tinea
barbae, Tinea corporis and Tinea pedis.
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History

• 1837 KOH positive from patient with Tinea
  corporis.
• 1842 Remak inoculated himself with infected
  skin from a patient and reproduced disease. This
  proved infectious nature.
• 1845 Cultured the organism. This was the first
  organism ever cultured from an infectious
  disease.
• 1845 Named the fungus after his professor J.L.
  Schoenlein. Known today as Trichophyton
  schoenleinii.
• Modern taxonomy done in 1892 by Raymond
  Sabouraud.

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Current Taxonomy

• A) Dermatophytes
• - Microsporum spp.
• Epidermophyton sp.
• Trichophyton spp.
• 45 to 50 species in above genera

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• Some authors call non-dermatophytic fungi
• B) Dermatomycoses
• Clinically, these cannot be differentiated from
  dermatophytoses. However, the etiologic agent
  are not dermatophytes. They are organisms that
  we used to call contaminants. Some believe
  they are more difficult to treat. The following
  are some occurrence rates
• - 3.5 in North America (nails)
• 4.5 to 9.5 in South America (nails)
• 20 in Africa (nails and feet)

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Some non-dermatophytic fungi implicated in
onychomycosis
Acremonium (Cephalosporium), Alternaria, Aspergill
us (11 spp.), Curvularia, Fusarium, Penicillium,
Scopulariopsis Scytalidium. - 1997 report
includes 34 different fungi
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C) Yeasts

• many genera , mostly Candida spp.
• 5 to 60 nail infections
• Many yeast are normal flora

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Diagnostic methods 1) Clinical 2) Direct
examination 3) Culture
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1) Clinical aspects of dermatophytoses,
dermatomycoses and yeast infections simulating
dermatophytoses
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Fourteen year old Uyghur school girl from Kashgar
City area (Xinjiang province, west China) with
tinea capitis and tinea corporis due to
Trichophyton violaceum. More than 2 of Uyghur
school children in this area have severe tinea
capitis due to this organism and T. verrucosum.
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In KOH preparations from the edge of the large
lesion we saw numerous, septate, hyaline hyphae.
Skin scrapings were planted into Mycosel agar.
Two weeks later we identified the etiologic
agents as T. tonsurans.
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This patient is from the Philippines. Upon
culture we identified the etiologic agent as M.
gypseum.
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This case of tinea corporis was caused by
Trichophyton rubrum. The case was seen in Wuhan,
Hubei province, P.R.C. The patient was
successfully treated by Sporanox (itraconazole).
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This is the lesion of tinea corporis around the
waist in a patient with SLE. The lesion, which is
an atypical one, is scaly erythema without the
progressive clearing center and then the annular
outlines. The skin scraping culture grows T.
rubrum.
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This is an example of a child with tinea alba.
Note the bald areas on the head (A.B) and the
lesions spreading down to his cheek (C). This
infection developed over a period of several
weeks and responded very well to treatment.
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This is the characteristic lesion of ringworm
black-dot, which presents as multiple areas of
alopecia studded with black dots and some fine
scales. No scars left after cure (By Prof. Li
Jiawen ).
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This is a case of kerion caused by T.
mentagrophytes. The lesion is composed of many
(20-30) mini-abscesses with the inflammatory
infiltration basement. The surface of the lesion
has ulcers covered by crusts. Removing the crusts
reveals the necrotic tissue with loose and
broken-off hairs penetrating it. Exuding pus is
little. The patient has little pain and itching.
Scars are present after a cure.
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This picture shows kerion existence with tinea
alba.
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This is an atypical capitis, which is becoming
more common. On the scalp there are multiple
scaling patches which differ in size, alopecias
and broken hairs. However, neither has the fungal
sheath nor the black dot and pustules. The skin
scraping and broken hairs were planted onto
Sabourauds medium. The result was T. violaceum.
(By Prof. Li Jiawen )
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An Example of Tinea Barbae
Difficult to diagnose Need infected hairs for
KOH. Cultures contaminated with bacteria.
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An Example of Onychomycosis
KOH scrapings of nail debris confirms fungal
etiology.
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The picture shows tinea unguium caused by T.
rubrum with paronychia and secondarily infected
by S. aureus.
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This case contracts onychomycosis caused by C.
albicans for 30 years. The involved nail is dark
brown with smooth surface. Hyperkeratosis occurs
under the nail plate and the thickness was up to
7 mm. There is paronychial inflammation around
the nail root. Massive pseudohyphae are seen in
the pathological section.
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This is an example of a case of tinea pedis. The
lesion took several months to develop to this
size. Without appropriate therapy, it would
continue to develop in this patient over a period
of several months or years.
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This is the so-called moccasin-type of tinea
pedis (athletes foot). This patient also has
onychomycosis. Cases of this type, that are
caused by Trichophyton rubrum, can be difficult
to cure. Often 4-5 weeks of treatment is
required with either Sporanox or Lamasil.
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• Direct Examination. Every fungus laboratory in
  the world uses 10 or 20 KOH to examine
  clinical specimens. For possible dermatophytosis
  10 is used for skin and hair 20 for
  nails.
• KOH means that hyphae or yeast were seen.
  Culture is necessary to identify the organism.

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KOH photomicrographs showing fungal hyphae.
This indicates a filamentous fungus is the
etiologic agent. Therapy can begin although a
culture is required to identify the etiologic
agent.
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KOH . This microscope has a micrometer used to
measure sizes of microscopic elements. Note the
lines with numbers. These lines are calibrated
for each lens.
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Hair Infections

• Ectothrix This is where spores are seen on the
  outside of the hair, e.g., Microsporum canis.
• 2) Endothrix This is where spores or hyphae
  are seen inside the hair, e.g., Trichophyton
  tonsurans.

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Ectothrix hair infection.
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Endothrix hyphae.
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Endothrix spores.
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• Culture
• a) Sabourauds and Potato Dextrose Agar are
  the most commonly used culture media.
• b) Incubate at room temperature (24? C).
• c) Incubation of 2-4 weeks required to
  produce mature, identifiable culture.
• d) Lactophenol Cotton Blue (LPCB) is the
  preferred mounting medium to examine fungi
  microscopically.
• e) In dermatology Chloromycetin and
  Actidione are incorporated into media to
  restrict growth of contaminants.

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Two plates of media were exposed to the air for
10 minutes both at the same site. On both of the
plates are dozens of fungal colonies growing on
each medium. The individual colonies differ in
size, shape, and color. Each one of the colonies
arose from airborne spores which landed on the
medium during the exposure period and then
developed into a characteristic colony. The
medium in the plate which contains the smaller
colonies (A) is similar to the medium in the
other plate except that it contains (1) Actidione
(cycloheximide), an antibiotic which inhibits the
growth of many of the so-called contaminating or
airborne fungi and (2) Chloromycetin
(chloramphenicol), an antibiotic which inhibits
the growth of many bacteria.
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Why culture?

• Therapy Some organisms are more difficult to
  treat.
• Epidemiology You cannot eradicate a disease if
  you dont know the source in nature, e.g., SARS.
• Publish Journals will not accept a paper unless
  the organism is named.
• Research You must know the name of the
  etiologic agent.
• Grants To obtain grant money you must know the
  name of the etiologic agent.

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The following are examples of colony gross
morphology of a few dermatophytes.
Microsporum canis
Trichophyton mentagrophytes
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Trichophyton mentagrophytes
Trichophyton rubrum
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Trichophyton rubrum with diffusible
pigment
Trichophyton concentricum
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Definitive Identification of Etiologic Agents is
Dependent Upon Microscopic Examination.
The following are photomicrographs of several
dermatophytes. Note the morphology of the spores
and their arrangements.
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Microsporum canis. Note the large spores, thick
walls and numerous septa. Frequent caused of
Tinea capitis and Tinea corporis in China.
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Microsporum gypseum. Note thin-walled spores
with 2-5 septa. Geophilic and causing Tinea
barbae.
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Trichophyton mentagrophytes. On left note single
macroconidium and numerous microconidia arranged
en grappe. On right note spiral hyphae and
numerous round microconidia (spores). Common
cause of several dermatophytoses in China.
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Trichophyton rubrum. Note numerous round to oval
microconidia (spores) not arranged en grappe.
Common cause of several dermatophytoses in China.
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Trichophyton tonsurans. Note round to oval
spores some of which form small balloons. Hyphae
stained differentially with LPCB. Common cause
of Tinea capitis in numerous countries,
especially the USA.
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Special tests to identify some dermatophytes

• Urease test. This helps to differentiate T.
  mentagrophytes to T. rubrum.
• Trichophyton agars 1-7. A series of biochemical
  test that are useful to differentiate several
  Trichophyton spp.
• Hair penetration test. Accepted worldwide to
  differentiate T. mentagrophytes and T. rubrum.
• Molecular Biology tools, eg.,PCR.

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Left. Hair penetration for T. mentagrophytes.
Right. Hair penetration negative for T. rubrum.
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Dermatophytes of Importance in Asia
MOST COMMON
In hair
Disease(s)
Source
Organism
ectothrix
capitis, corporis
Z
M. canis
ecto(zoo)
corporis, pedis, nail
A,Z
T. mentagrophytes
rare
corporis, pedis, nail
A
T. rubrum
endothrix
corporis, capitis
A
T. tonsurans
A anthropophilic/ G- geophilic/ Z- zoophilic
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How are dermatophytes spread (disseminated)?

• Anthropophilic. These are organisms which
  primarily infect man and are disseminated man to
  man.
• Geophilic. These are organisms which primarily
  live in soil. Thus they are spread to man
  following contact with soil.
• Zoophilic. These are organisms which primarily
  live on animals other than man. Thus they are
  spread to man by contact with infected animals.

NOTE Many dermatophytes may be spread by
fomites. These are objects by which
dermatophytes can be spread to man, e.g., an
organism maybe anthropophilic but can be spread
to man by contact with contaminated clothing,
hats, hair brushes.
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Therapy

• The most commonly used oral medications are
• Griseofulvin. Used only for the treatment of
  Tinea capitis. Very effective and inexpensive.
• Lamasil. Extremely effective against
  dermatophytoses caused by classical
  dermatophytes.
• Sporanox. Extremely effective against
  dermatophytoses, dermatomycoses and numerous
  systemic mycoses (e.g., yeast infections).
• Numerous topical agents are effective for small
  localized lesions.

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Thank You!