Fungi

Question 1

Difference between yeast and filamentous fungi?

Answer 1

Yeast- Unicellular, divide and grow via budding.

Filamentous- Multi cellular rods. Divide and grow via hyphae & spores

Question 2

What are the different classes of anti-fungal therapies, and what are their basic mechanisms of action?

Answer 2

Azoles, Echinocandins, Allylamines; inhibit membrane synthesis
Polyenes; inhibit membrane function
Flucytisone, Griseofulvin; Inhibit nucleic acid synthesis

Question 3

How do Azoles work?

Answer 3

Inhibit the fungal P450 enzyme

Question 4

Name a topical azole used for Candida, tinea pedis, tinea cruris…

Answer 4

Clotrimazole

Comes in creams and pessories; not for use on hair/nails as it cannot penetrate these areas.

Question 5

What three fungi are known as dermatophytes?

Answer 5

Microsporum
Epidermophyton
Trichophyton

Question 6

What anti-fungal is excreted unchanged by the kidenys, can penetrate the CNS, and is used as an oral treatment for candida, dermatophyte and Cryptococcus?

Answer 6

Fluconazole

Candida krusei is naturally resistant to fluconazole, so is often found in patients previously traeated with fluconazole

Question 7

What anti-fungal used to treat candidaemia?

Answer 7

Fluconazole; PO

Question 8

What anti-fungals are used to treat Invasive aspergillus?

Answer 8

Amphotericin B IV, or

Voriconazole IV

Question 9

What anti fungal is used to treat a fungal nail infection? And involvement of how many nails indicates treatment?

Answer 9

2+ nails infected req for treatment.
Topical (or oral) terbinafine used

or Amorlfine nail laquer can be used

Question 10

What is the mechanism of action of Polyene anti-fungals, and list two examples.

Answer 10

Bind ergosterol in cell membrane and form a pore; leakage of cations.

Amphotericin B
Nystatin

Question 11

What is nystatin used to treat?

Answer 11

It is a topical treatment (not absorbed orally), used to treat superficial candidiasis infection:
Oral thrush
Nappy rash

Question 12

What are the side effects of amphotericin B?

Answer 12

Can cause hypokalaemia in renal imparment, and worsen renal function

Question 13

What causes ring worm?

Answer 13

Any dermatophyte infection causes ring worm ‘tinea’.
Microsporum
Epidermophyton
Trichophyton

Question 14

Who is affected by hypersensitivity pneumonitis, and what are some causative agents?

Answer 14

Healthy people following heavy exposure to:
Aspergillus
Avian proteins (pigeon fancier’s lungs)
Organic dusts

Question 15

What type of hypersensitivity reactions are involved in hypersensitivity pneumonitis?

Answer 15

Type 3 & 4

Question 16

What are the signs and symptoms of hypersensitivity pneumonitis?

Answer 16

fever, dyspnoea, cough, flu-like
Crackles at end of expiration, restrictive lung function, x-ray diffuse reticulo-nodular shadowing, precipitin reaction causing serum antibodies, bronchial lavage contains high lymphocyte count.