Cutaneous mycoses

1
Medical Mycology
???? ??????????????????????????????
????????????? ?.?.
2
Medical Mycology

• Pathogenic fungi
• Human to Human
• Animal to Human

Internal Organs 35
Severe 20
Skin 45
3
Fangal Pathogensis

• Accession - adhesin, compettition
• Multiplication
• Resistance to Host Defence System
• Damage to host tissue - Metabolite

4
General Consideration

• Extracellular (except some yeast)
• Antigenicity of cell wall
• CMIR
• Damage host by metabolic products
• Eukaryotic drug

5
Mycotic Infection

• Factors influence mycotic infection
• -Host
• -Causative Agents

• Pathogenic Mechanism
• - Allergy
• - Toxin
• - Invasion

Superficaial Infection Cutaneous
Infection Subcutaneous Inf. Systemic Inf.
6
Entry Fungi rarely cause disease in healthy
immunocompetent hosts. Disease results when fungi
accidentally penetrate host barriers or when
immunologic defects or other debilitating
conditions exist that favor fungal entry and
growth
Adaptation and Propagation Fungi often develop
both virulence mechanisms (e.g., capsule and
ability to grow at 37oC) and morphologic forms
(e.g., yeasts, hyphae, spherules, and sclerotic
bodies) that facilitate their multiplication
within the host.
7
Host Factors Healthy, immunologically-competent
individuals have a high degree of innate
resistance to fungi. Resistance to fungi is based
primarily upon cutaneous and mucosal physical
barriers. Severity of disease depends on factors
such as inoculum, magnitude of tissue
destruction, ability of fungus to multiply in the
tissue, and the immune status of the host.
8
Fungus Factors Enzymes such as keratinase, the
presence of capsule in Cryptococcus neoformans,
the ability to grow at 37C, dimorphism, and
other as yet undefined factors contribute to
fungal pathogenesis which involves a complex
interplay of many fungal and host factors.
9
Superficial mycoses

• ????????????
• ??????? ??? ????????????? ???
• ???????????????????????????
• ?????? ????? ?????????????????
• ?????? ????? ??????????????????? ??,??
  ?????????-??
• ????????????? ????? ?????
• ????????????????????????????????

• ??????????????????
• ?????? ???????????? ???? slide
• Handout 1 ???
• ?????????? ?????? 50 ????

10
Cutaneous mycoses

• Tinea versicolor
• Tinea nigra palmaris
• Black piedra
• White piedra
• Otomycosis
• Mycotic kerratitis

11
Tinea Versicolor
Malassezia furfur

• Definition
• Asymptomatic colonization

• Hypopigmentation

• Hyperpigmentation

• Seborrhoeic dermatitis

• Dandruff
• Fungaemia

12
Hypopigmentation
Aborigin, Asia
13
Hyperpigmentation form
Caucasian
14
Pityriasis Foliculitis
15
Predisposing factors

• broad spectrum antibiotics

• Steroid

• pregnancy

• Genetic predisposition (tern over rate)

• Emotion (possible endocrine or neurologically
  mediated factors)

• Alkalinity of skin (sweating)
• AIDs

16
Lab.Diagnosis

• Direct exam.
• Skin scraping
• 10 KOH preparation
• Parker Ink

• Culture
• Sabouraud Dextrose Agar
• Lipophilic yeast
• Flood with Olive oil

17

• Short fragments
• of hypha
• cluster of yeast

18
Malassezia
M.ovalae
M.furfur
M.paraovalae
19
Density of M.furfur
Yeast Mycelia
Normal Skin 103 Few Specific
Lesion 1.6x105 3x105 Non-specific
Lesion 1.9x104 0.8x103
20
(No Transcript)
21
Treatments

• Sodium thiosulfate 20 aq.
• Tropical Imidazole
• Shampoo
• Ketoconazole
• Zinc pyrithione
• Selenium sulfide lotion

22
Tinea nigra
Agent Phaeoannellomyces werneckii
Cladosporium werneckii

• palmar
• brown
• no scaling
• no inflam

23
Phaeoannellomyces werneckiiSynonym
Cladosporium werneckii Exophiala werneckii
Clinical significancePhaeoannellomyces
(Exophiala) werneckii is a common saprophytic
fungus believed to occur in soil, compost, humus
and on wood in humid tropical and sub-tropical
regions and is the causative agent of tinea nigra
in humans. Tinea nigra is a superficial fungal
infection of skin characterized by brown to black
macules which usually occur on the palmar aspects
of hands and occasionally the plantar and other
surfaces of the skin. Lesions are
non-inflammatory and non-scaling. Familial spread
of infection has been reported. Clinical group
Superficial mycoses Mycosis Tinea nigra Further
readingRippon, J.W. 1988. Medical Mycology. 3rd
Edition. W.B. Saunders Co., Philadelphia, USA.
24
Tinea Nigra
This is a superficial infection caused by a black
yeast variously known as Cladosporium or Hortae
werneckii. It is usually found in tropical areas
of the world. It is seen as circumscribe areas
of hyperpigmentation usually on the palms or
soles. Lesions are dark brown to black with
little scaling.
25
This is a photograph of tissue prepared for
direct examination with 10 KOH. Throughout the
field one can readily observe strongly septate
dematiaceous hyphae. Note No coloring agent
has been added to this slide the dark brown
color is produced in the fungus. This is how the
etiologic agent of tinea nigra appears in tissue.

26
An unusual case from the Philippines. Now you
know why this disease is no longer called tinea
nigra palmaris! A small portion scrapped skin,
placed in 10 KOH on a microscope slide will
reveal the dematiaceous, septate hyphae.
27
Conidia of Phaeoannellomyces werneckii.Colonies
are slow growing, initially mucoid, yeast-like
and shiny black. With age they develop abundant
aerial mycelia and become dark olivaceous in
color. Microscopically, colonies consist of brown
to dark olivaceous septate hyphal elements and
numerous 2-celled, pale brown, cylindrical to
spindle-shaped yeast-like cells that taper
towards the ends to form an annellide. Most
yeast-like cells also have prominent darkly
pigmented septa. Annellides may also arise from
the hyphae. Conidia are l to 2-celled,
cylindrical to spindle-shaped, hyaline to pale
brown and usually occur in aggregated masses.
28
Lab.Diag.
KOH-preparation
Yeast 2 cell ??????
29
Conidia of Phaeoannellomyces werneckii
30
Therapy
Topical antifungal agents as well as Whitefields
ointment have been used successfully.
31
Black Piedra
Agent Piedraia hortae

• ????????????????????????????
• ????????????????? ????

32
This is a low-magnification photograph of hair
with black piedra. Note the discrete nodules
surrounding the hair shafts (A,B).
33
This is a higher magnification photograph of hair
with black piedra. The lesion is very discrete,
surrounds the hair shaft and is dark brown.
Eventually the fungus may weaken the hair shaft
to the extent that the hair breaks off.
34
This is a still higher magnification of hair
infected with Piedraia hortai. Close observation
reveals that the nodule appears to be composed of
hundreds of spherical cells. These cells are the
asci, which contains ascospores. Such structures
can be seen more clearly when one places infected
hair in 1-2 drops of 10-20 KOH on a microscope
slide, adds a coverslip, heats the preparation
gently and the presses down very firmly on the
coverslip. In such preparations the piedra
nodules break open, and one sees many individual
asci containing ascospores and, occasionally,
groups of ascospores which have been squeezed out
of individual asci.
35
Ascospore
36
This is a culture of the fungus Piedraia hortai.
This fungus was cultured on Sabourauds medium and
incubated at room temperature. It normally takes
4-6 weeks incubation weeks incubation for a
colony to reach this size. The gross features of
this colony are that it is slow-growing, is
heaped up in the center, is a dark brown-black to
metallic green and is surrounded by a clear ring
where the young growing mycelium has not yet
produced the dark pigment. Microscopically, there
are few characteristic features. The fungus
produces dermatiaceous hyphae which may contain
numerous chlamydospores. No characteristic spores
are produced.
37
Hypha
38
White Piedra
Agent Trichosporon beigelii

• ??????????????? ????? ?????????
• ????????????????? ????

39
b) White Piedra
In this disease we also see nodules on the hair.
However, differing from black piedra, the nodules
are softer, pale in color and are only found on
hair in the groin and axillae.
40
In this picture we see hair with white piedra
(Trichosporon beigelii). Note that, when this
module is compared with that seen in black
piedra, it is not as discrete and lacks the dark
coloration. Additionally, this fungus does not
produce ascospores. When cultured on Sabourauds
agar and incubated for 2-4 weeks at room
temperature, this fungus produces a rough,
membranous, white to light tan colony.
Microscopically, the organism produces no
characteristic spores.
41
This is a 4-5 week old culture of Trichosporon
beigelii (T. cutaneum) grown on Sabourauds
medium at room temperature. This is the
etiologic agent of white piedra.
42
Therapy
The piedras are treated by removal of the hair
and application of topical antifungal
agents. Note White piedra must be
differentiated from trichomycosis axillaris which
is bacterial in etiology.
43
Otomycosis and Mycotic keratitis
Opportunistic fungi Mostly air born Localize Reinf
ection
44
Mycotic Keratitis
Fungus infection of the cornea of the eye. It
may be caused by one of numerous filamentous
fungi which are found in our environment. Normal
flora yeasts are also implicated. Under severe
conditions it can lead to blindness and fatal
invasion of the brain.
45
This is a rather typical case of mycotic
keratitis. The patient reported that several
months previously some foreign matter had lodged
in his eye.
46
In this case of mycotic keratitis the lesion is
very obvious. Scrapings from this eye were
examined in KOH preparations, and septate hyphae
were observed. Additional material was cultured,
and the etiologic agent was identified as a
Fusarium. The patient was given treatment with
topical amphotericin B and responded in a
satisfactory fashion.
47
This is what one sees in cases of mycotic
keratitis when infected tissue is observed
microscopically under direct examination
procedures. Note the presence of hyphae (A,B).
This particular organism was cultured on
Sabourauds medium and identified as an
Aspergillus species.
48
This, like the previous slide, is a direct
examination preparation from a case of mycotic
keratitis. Note the abundance of clear, septate
hyphae (A,B). When structures of this nature are
observed, there is no doubt that the etiologic
agent is a fungus.
49
This is a photomicrograph of Penicillium. Here we
see the brushes (A) with a few spores (B)
attached to them.
50
Absidia
51
This fungus, Fusarium, is another etiologic agent
of mycotic keratitis. This organism produces
clear septate hyphae which are not particularly
characteristic. The large macroconidia, shown
here, are septate, new-moon/banana-shaped spores.
Fusarium spp. also produce small spores called
microconidia.
52
Therapy

1. A 5 solution of natamycin applied topically.
2. Topically applied Amphotericin B, oral Sporanox
   (150 dilution of Sporanox in ophthalmic
   solution) and ketoconazole in suspension have
   been used in difficult cases.
3. If thermophilic Aspergillus spp. are involved the
   organism may invade the brain. Few drugs are
   successful in such cases.

53
Otomycosis
Fungus and yeasts infection of the external
auditory canal of the ear. Numerous common fungi
have been implicated. Some investigators
believe this is not a true disease because tissue
invasion and destruction has not been
demonstrated.
54
Aspergillus flavus
55
(No Transcript)
56
(No Transcript)
57
Fusarium
58
(No Transcript)