DERMATOPHYTES K R.pptx

1. DERMATOPHYTES
(SUPERFICIAL MYCOSES)
K R MICRO NOTES 1

2. INTRODUCTION
 Dermatophytes are cutaneous fungi which infect only keratinized
tissue by liberating keratinase enzyme which helps them to invade
keratinized tissue.
 Ringworm (Tinea)infections are common diseases of the startum
corneum of the skin, hair and nail . They are referred to as
“ Dermatophytosis” or tinea .
 Ringworm infections are caused by about 20-40 species of
dermatophtye fungi which are grouped into three genera:
Trichophtyon – Hair, skin, nail
Microsporum – Hair, skin
Epidermophyton – Skin, nail
K R MICRO NOTES 2

3. Epidemiology
• Anthropophilic D.Gruby (1842-1844) detected the fungus in
– Man tinea as a causative agent and C.P.Robin (1853)
• Zoophilic described Microsporum mentagrophytes that
– Animals was transferred to trichophyton by Blanchard
• Geophilic (1896).
– Soil
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4. K R MICRO NOTES 4

5. TRICHOPHTYON
CLASSIFICATION
Kingdom : Fungi
Division : Ascomycota
Class : Eurotiomycetes
Order : Onygenales
Family : Arthrodermataceae
Genus : Trichophyton
 The genus Trichophyton is characterized by the development of both Smooth-
walled , macro-conidia and micro-conidia.
 Most important and common causes of infections of the feet, skin and nails.
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6. TRICHOPHTYON
CLASSIFICATION
Kingdom : Fungi
Division : Ascomycota
Class : Eurotiomycetes
Order : Onygenales
Family : Arthrodermatacceae
Genus : Trichophyton
 The genus Trichophyton is characterized by the development of both Smooth-
walled , macro-conidia and micro-conidia.
 Most important and common causes of infections of the feet and nails.
K R MICRO NOTES 6

7. Morphology
• The morphologies vary depending on the growth temperature, growth medium
and the type of species.
• Most of the species produce either macroconidia or microconidia or both.
• Their occurrence of shapes and sizes depending on the medium of growth.
Macro conidia Micro conidia
 They are small, cigar shaped
(cylindrical).
 They are spherical in shape
 They have thick walled cell walls and
tend to occur in clusters.
 They may occur singly or in clusters
and they produce on the terminal
branches on the hypal structures.
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8. • Trichophytons produces spiral-shaped hypal structures, from which the conidial
spores originate.
• They do not form conidiophores.
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9. Important species of trichophyton
With conidia
• Trichophtyon rubrum
• Trichophtyon mentagrophytes
• Trichophtyon tonsurans
With hyphae
• T. schoenleinii
• T. violaceum
• T. verrucosum
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10. Trichophtyon rubrum
• It is the most common cause of dermatophytosis.
• It occurrence is world wide.
• It is anthropophilic species of dermatophytes.
• It is a keratinophilic filamentous fungus.
• It affects human feet, skin, and finger nails, causing chronic infections on
these body parts ( granulomatous lesions).
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11. • Micrscopically, endothrix and ectothrix invasion may be observed on infection.
They form both microconidia and macroconidia.
• Macroconida occur, they are in large numbers, with terminal projections.
• Microconidia occur, they vary in shapes and sizes. They may be slender calvate to
pyriform.
• Urease test is negative
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12. Trichophyton mentagrophytes
• This is a zoophilic species with a cosmopolitan distribution.
• it commonly affects animals such as mice, cats, horses, sheep and rabbits.
• In humans cause ringworm , majority in rural areas.
• Grape like clusters of microconidia.
• No red pigment.
• Hair perforation test is positive.
• Cigar shaped macroconidia
• Urease positive.
• It is a contagious fungus which primarily causes
tinea pedis , tinea unguium, tinea corporis and
Tinea capitis. K R MICRO NOTES 12

13. Pathogenesis
K R MICRO NOTES 13

14. Clinical Manifestations of Trichophyton spp infections
Tinea corporis
( ringworm)
Tinea pedis
(athlete’s foot)
Tinea cruris (jock
itch)
Tinea barbae  Tinea unguium
(onychomycosis)
 Caused by T.
mentagrophytes
Trichophyton rubrum
and T. mentagrophytes
Trichophyton rubrum
and T. mentagrophytes
Trichophyton rubrum
and T. mentagrophytes
Trichophyton rubrum
and T. mentagrophytes
 It affects the
nonhairy, smooth
skin.
It occurs in the
interdigital spaces on
feet of persons wearing
shoes.
It is associated with
groin erythematous
scaling lesions in the
intertriginous area
Affects the beard hair It affect the nail
 It is characterized by
circular patches with
advancing red,
vesiculated border
and central scaling.
By acute infection
associated with itching
and red vesicular .
It is characterized by
Edematous,
erythematous lesion.
The nails thickened or
crumbling distally ,
discolored , lusterless
 The infection is
pruritic
Chronic infection also
characterized by
itching, scaling, fissures.
And the lesions pruritic. It is usually associated
with Tinea pedis.
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15. Tinea corporis
Tinea pedis
Tinea cruris Tinea barbae Tinea unguium
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16. Laboratory diagnosis
• Specimen collection
• Direct examination
• Culture
• Identification
K R MICRO NOTES 16

17. Specimen collection
• Hair
– plucked , not cut, from edge of lesion.
• Skin
– wash, srape from margin of lesion.
• Nails
– Scrapings from nail bed or infected area.
• Transport in sterile petri dish
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18. Direct examination
• Examine hair for flourescence
– Wood’s lamp
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19. Direct examination
• Examine specimen for fungal elements
– Skin 10% KOH for one hour.
– Hair 20% KOH for 10 hours.
– Nails 20-40% KOH for 10 hours.
• With Calcofluor white stain
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20. Culture Media
• Trichophyton grow well in Sabouraud Dextorse agar within two weeks at room
temperature producing cylindrical, smooth walled macroconidia and
microconidia
• Trichophyton rubrum develops white, cottony surface and deep red nondiffusible
pigment in reverse growth . They produces small pear shaped micorconidia.
K R MICRO NOTES 20

21. Culture media
• Trichophyton mentagrophyte produces a cottony to granular growth,
grape clusters of spherical microconidia on terminal branches. They
also form coiled or spiral hyphae.
K R MICRO NOTES 21

22. Identification
• Identification based on the colonial appearance and color , pigment
production and micromorphology of any spores produced .
• Special test exist for differentiating certain morphologically similar
species. Thus, the ability of t. mentagrophytes to produce urease
within 2-4 days distinguishes from T. rubrum.
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23. Treatment
• Topical therapy is satisfactory for most skin infection, but oral antifungals are
required to treat infections of the nail and scalp, and severe or extensive skin
infections.
• Itraconazole and terbinafine are used for the treatment of tinea corporis, tinea
pedis and for the nails also.
• Tinea capitis (scalp infection)
Are treated for several weeks
With oral administration of
Griseofulvin or terbinafine.
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24. Microsporum
CLASSIFICATION
Kingdom : Fungi
Division : Ascomycota
Class : Eurotiomycetes
Order : Onygenales
Family : Arthrodermatacceae
Genus : Microsporum
Microsporum spp are dermatophyte fungi that cause cutaneous infections of
the hair, skin.
As a dermatophyte, it is restricted to the nonviable skin tissues because of its
inability to grow in temperatures above 37C.
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25. • It is highly transmissible fungus from animals to humans therefore it is a zoonotic
fungus.
• They occur world wide, naturally living in the soil.
• This include the Tinea capitis which cause the fungal infection of the scalp hairs
that fungi penetrate the hair follicles outer root sheath,
and result in an inflammatory types is characterized by
painful nodules that contain pus and losses hair.
it is common in 3-14 years children but it can affect any
group
• Tinea corporis affects the arms and legs , itching, scaling,
redness, rashes and may be dry. K R MICRO NOTES 25

26. Characteristics of Microsporum spp
• They reproduce asexually forming Macroconidia and microconidia.
Macro conidia Micro conidia
 They are larger asexual spores  They are smaller
 Hyaline and multiseptate  hyaline and single celled
 Spindle shaped to obovate  pyriform to clavate shaped , having smooth call wall
 They are 7-20 m by 30-160 m in size  2.5-3.5 m by 4.7 m in size
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27. Important species of Microsproum
• Microsporum gypseu
• Microsporum canis
• Microsporum audouinii
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28. Microsporum audouinii
• Anthropophilic
• Hair fluoresce yellow- green when examined under wood’s lamp.
• Velvety, brown colored colony
• Macroconidia – distorted shape or absent
• Terminal chlamydospore present
K R MICRO NOTES 28

29. Microsporum gypseu
• Geophilic
• Hair do not fluoresce
• Spindle shaped, round end macroconidia are abundant . There is no curve
at the end of macroconidia .
K R MICRO NOTES 29

30. Microsporum canis
• Zoophilic (Dogs and cats)
• Hair fluoresce yellow – green
• Spindle shaped, rough walled, multi segmented, curved end , warty
projections macroconidia are abundant.
• Microconidia are very few.
K R MICRO NOTES 30

31. Pathogenesis
K R MICRO NOTES 31

32. Laboratory diagnosis
• Specimen collection
• Direct examination
• Culture
• Identification
K R MICRO NOTES 32

33. Lab diagnosis
• Specimens
Skin scrapings, nail scrapings, tissue biopsies
• Direct examination
KOH wet mount using the skin scrapings and pus.
K R MICRO NOTES 33

34. Culture examination
• Potato Dextrose Agar
Microsporum audouinii produce pinkish-brown or salmon-colored fluffy colonies
K R MICRO NOTES 34

35. • Microsporum canis produces bright yellow colonies.
Trichophyton Agar
• Microsporum audouinii produces flat , white, suede-
like to downy, with yellow-brown reverse colonies with
a furry texture.
• Microsporum canis forms flat, white, suede-to downy , with yellow-brown
reverse colonies.
Rice Grain Agar
• Microsporum canis produces white aerial mycelium with the production of yellow
pigment.
K R MICRO NOTES 35

36. Treatment
• Topical or oral antifungals including imidazole, ciclopirox, naftifine or
terbinafine in cream, lotion or gel for mild – moderate lesions arising
due to tinea corporis and tinea capitis .
• Use of antifungal shampoos for treatment and also for the prevention
of fungal infection spread.
• Extensive infections can be treated with oral Itraconzole for a
prolonged period of time.
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40. INTRODUCTION
Madura foot is also know as “Mycetoma” or “Madura mycosis” ( tumor-like)
Mycetoma is a chronic, granulomatous infections of the skin, subcutaneous
tissue, fasica and bone.
Individuals who walks in barefoot in dry, dusty conditions and agriculture
fields.
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41. EPIDEMOLOGY
It was first identified in Madura , Tamil nadu (India) by
GILL (1842) Madura mycosis.
CARTER (1874) named the disease mycetoma and proved
its’ mycotic nature.
The first cases in Africa was described in Sengal in 1894
and in Sudan ( 1904).
The disease is most prevalent in tropical, subtropical
regions of Africa, and Central America.
K R MICRO NOTES 41

42. MYCETOMA - TYPES
Eumycetoma – due to fungus (40%)
Actinomycetoma – due to bacteria (60%)
K R MICRO NOTES 42

43. Eu Mycetoma Actino Mycetoma
Caused due to Caused by Fungi Caused by Bacteria
Grains Black or white White/red
Granules Black granules if caused by
Madurella mycetomatis
White granules if caused by
Pseudallescheria boydii
White to Yellow granules if caused
by Actinomadura madurae,
Nocardia species, Streptomyces
som-alien-sis
Pink to Red granules if caused due
to Actinomadura pelletieri
Sinues Appear late, few in number Appear early, numerous with raised
inflamed opening
Tumor Single, well defined margins Multiple tumor masses with ill
defined margins
Discharge Serous Purulent
Bone OsteoSclerotic lesions OsteoLytic lesions
Grains contain Fungal hyphae Filamentous bacteria
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47. Pathogenesis
Organism enter through a prick in the foot usually who walks in
barefoot
Reaches deeper plane in the foot
That causes chronic granulomatous inflammation
causes pale, painless, firm nodules
Formation of vesicles
Burst to form a discharging sinuses
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49. Lab Diagnosis
Specimen collection
Grains ( collect after cleaning with antiseptic , using sterile gaze or loop, press
the sinuses from periphery ).
Then sterile pads for 8-12 hour, it examined for color, size and consistency
which differ according the causative agents. Grains examined microscopically
after crushed between two slides with KOH or stained by gram.
K R MICRO NOTES 49

50. Culture
• Grains as well as exudate are cultured on suitable media .
• In case of black grains Sabouraud’s dextrose agar (SDA) and dermatophyte test
medium is suitable.
• If it is white grains SDA or malt extract agar as
well as blood agar are used and LJ media.
Incubation time and degree of temperature is
differ from bacterial isolates or fungi.
Lab diagnosis contd…
K R MICRO NOTES 50

51. Lab diagnosis contd…
• In fugus identify by observation of the growth rate, colony morphology,
production of conidia and their sugar assimilation patterns.
• In bacteria identified by their growth rate, colony morphology, urease test
• Acid fastness and media containing casein,
tyrosine, xanthine.
Nocardia is partially acid fast.
K R MICRO NOTES 51

52. Treatment
• SURGERY then Drugs
( but in pathogenesis they never mentioned about pain or complications)
Eumycetoma
Itraconazole
Amphotericin B
Actinomycetoma
Welsh regimen = Amikacin (systematic aminoglycoside)
+Cotrimoxazole (sulphamethoxazole + trimethoprim)
K R MICRO NOTES 52

53. Reference
• MEDICAL MICROBIOLOGY
– DAVID GREENWOOD
– RICHARD C.B.SLACK
• TEXTBOOK OF MICROBIOLOGY
– DR C P BAVEJA
• http://micronotes.com
• MEDICAL MICROBIOLOGY
– SATISH GUPTA
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