Subcutaneous mycoses

1. iii sem smsmc
SUBCUTANEOUS
MYCOSIS
Mycetoma
Dr. Dinesh Jain
Assistant Professor
Deptt. of Microbiology
SMS MC Jaipur

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

3. 16/12/07
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

10. smsmc
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.

12. smsmc

13. smsmc
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.

16. smsmc
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

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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)

18. smsmc
micro
Botryomycosis
 Similar condition caused by bacteria like
S.aureus, P.aeruginosa, CONS, E.coli.
Pr.vulgaris etc.
 2 types : cutaneous
visceral – ill debilitated pts

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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.

22. smsmc micro
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.

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Culture
 Inoculated on 2 sets of SDA, BHIA
 Incubated at 25°& 37°C.

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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

29. smsmc micro
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

31. smsmc micro
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

32. smsmc micro
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

33. smsmc micro
Sclerotic bodies - KOH
Sclerotic bodies - tissues

34. smsmc micro
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

35. smsmc micro
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

36. smsmc micro
PHAEOHYPHOMYCOSIS
 Seen in debilitated & immunodeficient hosts.
 Causes subcutaneous & systemic infection.
 Caused by dematiaceous fungi. Commonest
genera involved - Alternaria, Bipolaris,
Curvularia, Exophiala, Phialophora, etc.

37. smsmc micro
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

38. smsmc micro
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.

40. smsmc micro
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

41. smsmc micro
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

42. smsmc micro
Fontana Masson stain

43. smsmc micro
Treatment & prophylaxis
 No effective medical treatment
 Complete excision
 Cryosurgery.