2. INTRODUCTION
Heterogenous group of fungal infections
which are characterized by development of
clinical lesions in subcutaneous tissues at
the site of inoculation of etiological agents.
Disease process starts following a trivial
trauma, which is the sole source of
infection.
mycology aruna, Microbiology
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INTRODUCTION
Usually follow trauma.
Lesions develop at the site of implantation of
the etiological agent in the subcutaneous
tissue.
Includes – Mycetoma
- Sporotrichosis
- Rhinosporidiosis
- Chromoblastomycosis
- Phaeohyphomycosis
- Lobomycosis
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MYCETOMA
Chronic, slowly progressive granulomatous
infection of skin & subcutaneous tissues with
the involvement of underlying fasciae &
bones commonly affecting the extremities.
Reported by Gill from Madurai, S.India.
Maduramycosis or Madura foot.
Tropical & subtropical countries of Asia ,
Africa, Central & S.America.
5. smsmc
Classification of Mycetoma
Based on the causative agent
True Fungi – Eumycetoma
Aerobic filamentous bacteria (actinomycetes) -
Actinomycetoma
Based on the colour of grains
Bacterial agents – white to yellow grains except
Actinomadura pelletieri (red or pink)
Fungal agents – black as well as white grains.
6. ETIOLOGY
Fungal agents (25 agents)-saprotrophic
environmental fungi-Deuteromyctes(10
agents) or Ascomycetes(3 agents) cause
white grain mycetoma
Others cause black grain Mycetoma
smsmc micro
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Colour/texture of grains in Mycetoma
of various etiology
White to yellow/soft Brown to black Red
Nocardia
asteroides/brasiliensis
Madurella
mycetomatis/hard
Actinomadura
pelletieri
Acremonium/Fusarium
/Aspergillus nidulans
Madurella grisea/soft
Actinomadura madurai Phialophora
jeanselmei/soft
Streptomyces
somaliensis
Curvularia
geniculata/hard
Pseudollescheria
boydii
8. smsmc
Epidemiology
More prevalent in developing countries,
especially in the rural areas.
Young men 20 to 40 yrs of age
Field workers, farmers – prone to thorn prick
injury & trauma.
Prevalence in world : Eumycetoma (40%)
Actinomycetoma (60%)
9. ssmsmc
Pathogenesis & Pathology
Causative agent present in soil
Accidental trauma by thorns or splinter injury
Minor trauma & skin abrasions
Mycetoma of ear – use of wicks for removal
of earwax.
Mycetoma of back – carrying goods like
wood, grain bags, stones, etc
Mycetoma of the head & neck – bundles of
wood
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Pathogenesis & Pathology
Lesion begins as a small subcutaneous
swelling of the foot, which enlarges burrowing
into the deeper tissues & tracking to the
surface as multiple sinuses discharging
viscid, seropurulent fluid containing granules
or grains which are microcolonies of the
causative agent.
11. smsmc
Clinical features
Characterised by a triad of
clinical features irrespective
of the causative agent:
1. Tumefaction – tumor like
swelling
2. Multiple draining sinuses
3. Presence of grains or
granules in sinuses.
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Diagnosis
Radiodiagnosis – Xray, CT, MRI.
Laboratory diagnosis
- Proper h/o patient
- Gross examination of lesion by a microbiologist
Specimen – grains or granules
- pus / exudates or biopsy
Lesions cleaned with antiseptics & the grains
collected by pressing the sinus from the
periphery.
Gross examination of grains – size, shape,
texture, colour
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Direct Examination
KOH mount – grains
Eumycetoma : 2-6µ, wide interwoven hyphae
with large, swollen cells (chlamydospores) at the
margin of the lesion.
Actinomycetoma : filaments with a diameter of
0.5 - 1µ, coccoid to bacillary forms.
If hyphae seen on KOH mount, use special
stains.
15. smsmc
Direct Examination
Gram stain – gram +ve
branching filamentous
bacteria embedded in the
grain material.
Modified Acid fast staining
with 1% sulphuric acid – pink
colored filamentous bacteria
i.e. Nocardia Sps whereas
other actinomycetes are
non- acid fast.
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Culture
Different sets of media – both possibilities of
fungi & bacteria .
When Actinomycetoma is suspected on direct
examination - wash grains several times with
NS & then inoculate on SDA without
antibiotics, BA, LJ & BHIA.
When Eumycetoma is suspected – wash
grains several times in NS with antibiotics(Pn)
& inoculate it on SDA with antibiotics.
- actidione not added.
- incubated at 25° & 37°C
17. smsmc micro
Treatment & prophylaxis
Eumycetoma – Oral Ketoconazole &
Itraconazole
AMB for Madurella & Fusarium species.
Actinomycetoma – Sulfonamides,
Tetracyclines, Streptomycin, Amoxycillin,
Clavunate & Amikacin
Protracted case – Surgery (debridement with
skin graft)
19. smsmc micro
SPOROTRICHOSIS
Caused by Sporothrix schenckii, a dimorphic
fungus.
Most common in USA.
Found on plant, thorns & timber
Infection is acquired through thorn pricks or
other minor injuries
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Pathogenesis & pathology
Spreads from primary site
to the regional LNs through
lymphatics
Mostly involves upper limbs
Pyogranulomatous reaction
Clinical features - Nodules
on the skin, subcutaneous
tissue and in the LNs which
later soften & ulcerate.
Lymphocutaneous sporotrichosis
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Laboratory Diagnosis
Specimens – pus, exudate & aspirate from
nodules.
- curettage or swabs from open lesions.
Direct Examination
Gram’s stain – gram+ve, irregularly stained
yeast cells.
CFW – very useful.
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Direct examination
Tissues – organisms appear as cigar shaped
bodies (yeast cells) 3-5µ in diameter.
“Asteroid bodies” in the lesion – central
fungus cell surrounded by a refractile
eosinophilic halo, called “ Splendore-Hoeppli”
phenomenon : due to immune complex
deposition around the organism.
24. smsmc micro
LPCB mount from Culture
septate hyphae - very thin & carry flower like
clusters of small conidia on delicate sterigmata.
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Treatment & Prophylaxis
Saturated solution of KI – drug of choice
Oral Ketoconazole or Itraconazole
AMB – disseminated & CNS disease.
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RHINOSPORIDIOSIS
Caused by a hydrophilic protist,
Rhinosporidium seeberi
1st identified in Argentina, but majority of cases
occur in India and Sri lanka.
High incidence among people who frequently
bathe along with domestic animals in ponds,
tanks, lakes
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Clinical Features
Chronic granulomatous disease of mucous
membrane.
Characterised by the development of friable
polyps in the nose, mouth or eye.
Miscellaneous forms –
Buccal cavity,vagina,
vulva, penis, urethra
or rectum
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Laboratory Diagnosis
Cannot be cultured
Direct Examination
FNAC, Biopsy of lesion, Nasal washing
- Contains sporangia
filled with thousands of
sporangiospores(6-9µ)
embedded in a stroma
of connective tissue &
capillaries
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Treatment & Prophylaxis
Radical Surgery:- Excision/ Electrocautery
Medical therapy :- not useful
DDS (widely used)
Recurrence common
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CHROMO BLASTOMYCOSIS
Caused by dematiaceous (pigmented) fungi
Commonest fungi - Fonsecaea Species
Phialophora verrucosa
Cladosporium carrionii
Also called as Verrucous dermatitis
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Clinical features
Soil saprobes enter the skin by traumatic
implantation and lesions develop slowly around
the site of implantation
Warty cutaneous nodules which resembles
flouts of cauliflower - Verrucous dermatitis
Frequently ulcerate
Confined to the subcutaneous tissue of the feet
and lower legs
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Laboratory Diagnosis
Direct Examination
Dry crusty material from the surface of the
lesions
1. KOH w/m –
dark brown, multicellular structures, 5-12μ in
diameter that divide by transverse septation.
-Called sclerotic bodies, medlar bodies, copper-
pennies bodies or muriform cells
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Direct examination
Medlar bodies - characteristic tissue form -
facilitates survival of organism in host tissues.
2. Tissue Stains - for Biopsy specimens
HE, Giemsa & Fontana- Masson
- Sclerotic bodies very well seen
Fungal culture - SDA with actidione and
antibiotics
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Treatment & Prophylaxis
Responds poorly to available therapies.
Cryotherapy, Thermotherapy, Laser
therapy,Chemotherapy and Surgery.
Flucytosine (commonly used drug)
Itraconazole, Fluconazole, Terbinafine
*Relapses are frequently seen
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PHAEOHYPHOMYCOSIS
Seen in debilitated & immunodeficient hosts.
Causes subcutaneous & systemic infection.
Caused by dematiaceous fungi. Commonest
genera involved - Alternaria, Bipolaris,
Curvularia, Exophiala, Phialophora, etc.
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Clinical Features
Clinical types:
1. Brain abscess caused by Cladosporium
2. Subcutaneous or intramuscular lesions with
abscess or cysts - single circumscribed
lesion with a central cavity filled with pus
and surrounded by a fibrous wall
3. Cutaneous lesions
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Laboratory Diagnosis
Specimen
Aspirates from cysts
Curreting from plaques, nodules and drained
abscess
Direct Examination
KOH mount
- Pigmented hyphae 3-4µ in dia.
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Fungal Culture
SDA with actidione at 25º & 37ºC.
Treatment & Prophylaxis
Local excision for subcutaneous forms
Invasive infections – I.V. AMB + Oral
Flucytosine.
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LOBOMYCOSIS
Caused by Lacazia loboi
(Hydrophilic fungus) : exists
only as yeast cells.
Involves exposed parts
Presence of macule, papule,
keloid, verrucous, nodular
lesions or plaques & tumors.
Lesions are painless with
slight pruritis
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Laboratory Diagnosis
Direct Examination of curettage / biopsy -
crushed
a. KOH w / m
b. CFW
- spheroid, yeast - like cells, 5 -12µ
- thick - walled & multinucleate.
- form chain with cells joined by bridges.
c. HE – may show ‘asteroid bodies’
• Culture – cannot be cultured