Dermatophytes

 

DERMATOPHYTES

Q. 1

Most common organism causing tinea capitis in India is:

 A Microsporum
 B Trichophyton tonsurans
 C Epidermophyton
 D Trichophyton violaceum

Q. 1

Most common organism causing tinea capitis in India is:

 A Microsporum
 B Trichophyton tonsurans
 C Epidermophyton
 D Trichophyton violaceum
Ans.D

Explanation:

The most common organisms causing Tinea capitis in the United States are Trichophyton tonsurans.

T. Violaceum is the commonest cause od Tinea Capitis in India.

Ref: Pediatric Primary Care: Child Care, By Raymond C. Baker, Pages 30-31; Clinical Pediatric Dermatology, By Thappa – Elsevier India 2009.


Q. 2

Athlete’s foot infection is caused due to:

 A Trichophyton
 B Candida
 C Papilloma virus
 D E.coli

Q. 2

Athlete’s foot infection is caused due to:

 A Trichophyton
 B Candida
 C Papilloma virus
 D E.coli
Ans.A

Explanation:

Athlete’s foot is a health hazard associated with contact with contaminated swimming pool water. It is caused by Epidermophyton or Trichophyton species.

Ref: Park 21st edition page: 673.

Q. 3

Dermatophytes infecting-

 A Subcutaneous tissue
 B Systemic organs
 C Nails, hair and skin
 D Superficial skin and deep tissue

Q. 3

Dermatophytes infecting-

 A Subcutaneous tissue
 B Systemic organs
 C Nails, hair and skin
 D Superficial skin and deep tissue
Ans.C

Explanation:

Ans. is ‘c’ i.e., Nails, hair and skin

DERMATOPHYTES

.    Filamentous fungi that infect only superficial keratinized tissues – skin, hair and nails.

.     Cause a variety of clinical conditions, collectively known as dermatophytoses, tinea or ring worm.

.  Have been classified into three genera:

Trichophyton – Microsporum

– Epidermophyton

.   In lesions appear as :

– Hyphae

– Arthrospores

.  In culture on sabouraud’s agar form :

– Septate hyphae

– Asexual spores (micro and macroconidia)

.   Differentiation is based mainly on macroconidia.

Trichophyton

Microsporum

Epidermophyton

Site

Hair, skin and nail

Hair and skin

Skin and nail

Microconidia

Abundant, arranged in

clusters along hyphae

Single (multicellular)

Absent

Macroconidia

Relatively scanty, elongated

with blunt ends –> Pencil

or cylindrical shaped

Single (multicellular),

Spindle shaped

. Groups of 2 or 3

. Club shaped

or pear shaped


Q. 4

A patient made a self-diagnosis of athlete’s foot (tinea pedis) and began using a product advertised on television. The condition improved but did not clear and then the patient showed himself to a Dermatologist. A skin scraping was sent to the laboratory for culture, including culture for fungi. The fungal culture yielded a slow growing colony, which produced a few small microconidia. This is consistent with isolation of a dermatophyte of the genera –

 A Trichophyton
 B Microsporum
 C Epidermophyton
 D Trichosporon

Q. 4

A patient made a self-diagnosis of athlete’s foot (tinea pedis) and began using a product advertised on television. The condition improved but did not clear and then the patient showed himself to a Dermatologist. A skin scraping was sent to the laboratory for culture, including culture for fungi. The fungal culture yielded a slow growing colony, which produced a few small microconidia. This is consistent with isolation of a dermatophyte of the genera –

 A Trichophyton
 B Microsporum
 C Epidermophyton
 D Trichosporon
Ans.A

Explanation:

Ans. is ‘a’ i.e., Trichophyton

.    Dermatophytes can be identified by their colonial appearance and microscopic morphology after growth for 2 weeks at 25°c on sabouraud’s dextrose agar.

.   Differential diagnosis of Dermatophytes on the basis of Macroconidia and microconidia

General

Microconidia

Macroconidia

Trichophyton

Abundant microconidia, arranged in clusters

along hyphae

Relatively scanty, elongated with

blunt ends

Microsporum

Single microconidia (multicellular)

Single macroconidia (multicellular)

Epidermophyton

No microcondia

Macroconidia in groups of 2 or 3


Q. 5

T. capitis (endothrix) is caused by –

 A Epidermophyton
 B T.tonsurans
 C T.violaceum
 D b and c

Q. 5

T. capitis (endothrix) is caused by –

 A Epidermophyton
 B T.tonsurans
 C T.violaceum
 D b and c
Ans.D

Explanation:

Ans. is ‘b’ i.e., T. tonsurans; ‘c’ i.e., T. violaceum

Two types of hair infection may occur :

  1. Ectothrix —>                Arthrospores are produced in a sheath surrounding the hair.
  2. Endothrix —>              Arthrospores are inside the hair shaft.

Hair infection

Ectothrix                                                Endothrix

. M. audouinii                                      . T. tonsurans

. M. canis                                              . T.violaceum

. T. mentagrophytes                            . T. schoenleinii


Q. 6

Which of the following does not produces dermatophytosis in India –

 A Trichophyton rubrum
 B Trichophyton mentagrophytes
 C Microsporidium distortum
 D Epidermophyton floccosum

Q. 6

Which of the following does not produces dermatophytosis in India –

 A Trichophyton rubrum
 B Trichophyton mentagrophytes
 C Microsporidium distortum
 D Epidermophyton floccosum
Ans.C

Explanation:

Ans. is ‘c’ i.e., Microsporidium distortum

Skin disease

  1. Tinea pedis (Athlete’s foot)
  2. Tinea cruris (jock itch)
  3. Tinea unguium (Onychomycosis)
  4. Tinea corporis (ringworm)
  5. Tinea capitis
  6. Tinea barbae

Dermatophvtes most commonly responsible

T. rubrum, T. montagrophytes, E.floccosum.

T.rubrum, E.floccosum

See previous explanations

T.mentagrophytes

Important dermatophyte pathogens of man

Epidermophyton floccosum

—>

Trichophyton mentographytes

–>

T. rubrum

—>

T. Tonsurans

—>

Worldwide distribution

Worldwide distribution

Worldwide distribution

Europe and America

Important dermatophyte pathogens of animal

M. distortum                          –>           Australia, USA

M. canis                                  —>         Worldwide

M. nanum                               –>           Worldwide

T. equinum                             –>           Worldwide

T. verrucosum                        –>           Worldwide

T. simii                                     –>           India

Coming back to question

T. rubrum, T. mentographytes and E. floccosum have world wide distribution (including India), while M. distortum is found in Australia & USA.


Q. 7

Dermatophytoses in caused by –

 A Herpes simplex
 B Papilloma virus
 C Trichophyton
 D Candida

Q. 7

Dermatophytoses in caused by –

 A Herpes simplex
 B Papilloma virus
 C Trichophyton
 D Candida
Ans.C

Explanation:

Ans. is ‘c’ i.e., Trichophyton


Q. 8

The causative agent of Favus is –

 A Microsporum audounii
 B Microsporum canis
 C Trichophyton mentagrophyte
 D Trichophyton schoenleinii

Q. 8

The causative agent of Favus is –

 A Microsporum audounii
 B Microsporum canis
 C Trichophyton mentagrophyte
 D Trichophyton schoenleinii
Ans.D

Explanation:

Ans. is ‘d’ i.e., Trichophyton schoenleinii


Q. 9

Which does not cause Tinea Capitis

 A Epidermophyton
 B Microsporum
 C Trichophyton Rubrum
 D Trichophyton Violaceum/Schoenleinii

Q. 9

Which does not cause Tinea Capitis

 A Epidermophyton
 B Microsporum
 C Trichophyton Rubrum
 D Trichophyton Violaceum/Schoenleinii
Ans.A

Explanation:

A i.e. Epidermophyton


Q. 10

Most common organisim causing T. capitis is

 A Trichophyton tonsurans
 B Microsporum
 C Epidermophyton
 D Candida albicans

Q. 10

Most common organisim causing T. capitis is

 A Trichophyton tonsurans
 B Microsporum
 C Epidermophyton
 D Candida albicans
Ans.B

Explanation:

B i.e. Microsporum


Q. 11

Black dot ring worm is caused by-

 A Microsporon
 B Trichophyton
 C Epidermophyton
 D Candida

Q. 11

Black dot ring worm is caused by-

 A Microsporon
 B Trichophyton
 C Epidermophyton
 D Candida
Ans.B

Explanation:

B. i.e. Trichophyton


Q. 12

An eleven year old boy is having tinea capitis on his scalp. The most appropriate line of treatment is:

 A Oral griseofulvin therapy
 B Topical griseofulvin therapy
 C Shaving of the scalp
 D Selenium sulphide shampoo

Q. 12

An eleven year old boy is having tinea capitis on his scalp. The most appropriate line of treatment is:

 A Oral griseofulvin therapy
 B Topical griseofulvin therapy
 C Shaving of the scalp
 D Selenium sulphide shampoo
Ans.A

Explanation:

A i.e. Oral griseofulvin

Tenia capitis is most commonly caused by Microsporum canis > Trichophyton tonsurans; and never caused by Epidermophyton as it does not involve hair.

It presents with localized non-cicatrial (mostly) alopecia, itching, scaling with or without boggy swelling of scalp & easily pluckable hair.

Tinia capitis is diagnosed by potassium hydroxide (KOH) wet mounts of hair & scale and treated by griseofulvin.

Griseofulvin is used systemically only for dermatophytosis, it is ineffective topically. It is the drug of choice for treatment of tinea requiring systemic therapy. Griseofulvin has no role in treatment of Tinea versicolar & candida.


Q. 13

Grisefulvin given for the treatment of fungal infection in the fingure nail dermatophytosis for how much duration

 A 4 weeks
 B 6 weeks
 C 2 months
 D 3 months

Q. 13

Grisefulvin given for the treatment of fungal infection in the fingure nail dermatophytosis for how much duration

 A 4 weeks
 B 6 weeks
 C 2 months
 D 3 months
Ans.D

Explanation:

D i.e. 3 months

Tinea unguium is dermatophyte infection of nail plateQ. It is treated by topical ciclopiro oleamine & amorolfineQ (in cases without nail matrix involvement) and/or oral terbinafine, itraconazole, fluconazole and griseofulvinQ (in cases with nail matrix involvement).


Q. 14

About dermatophytes all are true execpt

 A Candida albicans usually cause systemic infection
 B Dermatophytes involve superficial layers of skin
 C Microsporum doesn’t involve nail
 D Epidermophyte doesn’t involve hair

Q. 14

About dermatophytes all are true execpt

 A Candida albicans usually cause systemic infection
 B Dermatophytes involve superficial layers of skin
 C Microsporum doesn’t involve nail
 D Epidermophyte doesn’t involve hair
Ans.A

Explanation:

A i.e. Candida albicans usually cause systemic infection

Candidiasis may present as buccal creamy curd like pseudomembrane (thrush) or thickness, erosion & discoloration of web space (erosio interdigitalis blastomycetica)Q. It is most common fungal infection of female genital tract. Amphotericin B is drug of choice in systemic candidiasisQ.


Q. 15

Dermatophytes can affect:

March 2012

 A Hair
 B Nail
 C Scalp
 D All of the above

Q. 15

Dermatophytes can affect:

March 2012

 A Hair
 B Nail
 C Scalp
 D All of the above
Ans.D

Explanation:

Ans: D i.e. All of the above

Three genera of dermatophytes infect skin and appendages:

Trichophyton (skin, hairs and nails), Microsporum (skin and hairs) and Epidermophyton (skin and nails)


Q. 16

Tinea corporis is commonly caused by all the following except ‑

 A T. rubrum
 B T. verrucosum
 C

E. floccosum

 D

M. canis

Q. 16

Tinea corporis is commonly caused by all the following except ‑

 A T. rubrum
 B T. verrucosum
 C

E. floccosum

 D

M. canis

Ans.D

Explanation:

Ans. is ‘d’ i.e., M. Canis


Q. 17

Systemic infection is caused by all fungi except ‑

 A Cryptococcus
 B

Histoplasma

 C Dermatophytes
 D Paracoccidioides

Q. 17

Systemic infection is caused by all fungi except ‑

 A Cryptococcus
 B

Histoplasma

 C Dermatophytes
 D Paracoccidioides
Ans.C

Explanation:

Ans. is ‘c’ i.e., Dermatophytes



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