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PM3A > FUNGAL INFECTIONS > Flashcards

FUNGAL INFECTIONS Flashcards

1
Q

What drugs come under the polyene class?

A

Amphotericin B

Nystatin

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2
Q

What is amphotericin B?

A

Polyene macrolide - broad spectrum kills most fungi - fungicidal. Used oral or IV
- IV route very toxic so used for life threatening systemic infections e.g. cryoptococcal meningitis

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3
Q

What is nystatin?

A

Polyene macrolide - local or topical (oral suspension) for oral infections and cream for skin candida.
Broad spectrum

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4
Q

Mechanism of action of polyenes?

A

Bind to ergosterol
Form pores in the PM
Leaks K+ / Mg2+ cause . cell cannot maintain ionic balance due to pores
causes cell lysis
Fungicidal depending on conc - note that . high enough concs . will bind to cholesterol too which will affect human cells

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5
Q

What drugs come under the azole class?

A
  1. Imidazoles such as miconazole, clotrimazole, ketoconazole
  2. Triazoles e.g. fluconazole, itraconazole, voriconazole, posaconazole
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6
Q

are triazoles broad spectrum? if so what?

A

Yes - candida, crytococcusm, aspergillus

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7
Q

Mechanism of action of azoles?

A

Inhibit lanosterol 14-alpha demethylase CYP450 which interferes with ergosterol synthesis and disrupts PM - fungistatic

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8
Q

are imidazoles broad spectrum

A

Yes - dermatophytes and candidasis

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9
Q

Brand names for:
miconazole
ketoconazole
clotrimazole

A

miconazole - daktarin
ketoconazole - nizoral
clotrimazole - canesten

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10
Q

What is flucytosine?

A

Antifungal (synthetic is fluoropyrimidine) - Converted to 5-FU which disrupts DNA/RNA synthesis (competes with uracil for RNA synthesis)

  • Fungistatic
  • used in combo with other drugs for severe cryptococcal or candida systemic infections
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11
Q

Is flucytosine used alone?

A

No - in combo with others for severe cryptotoccal or candida systemic infect

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12
Q

What class is griseofulvin and MoA?

A

Benzofuran –> binds to polymerised microtubules and inhibits mitosis to stop growth of fungi - thus fungistatic

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13
Q

What is the spectrum of griseofulvin?

A

Limited . - dermatophytes e.g. tinea capitis

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14
Q

What are the S/E of griseofulvin?

A

N&V, anorexia, rash, urticaria

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15
Q

What drugs are included in allylamines class and MoA?

A

Terbinafine (Lamisil) –> mainly on dermatophytes
MoA: inhibits squalene expoxidase to inhibit generation of lanosterol from squalene in ergosterol biosynthesis
- fungistatic / fungicidal

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16
Q

What class of drugs is amorolfine?

A

Morpholine (amorolfnie is synthetic)

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17
Q

MoA of amorolfine and spectrum?

A

Spectrum mainly dermatophytes and yeast

MOA: inhibits delta 14 reductase and delta 7-8 isomerase so interferes with ergosterol synthesis - usually fungicidal

18
Q

What are echinocandins?

A

Lipopeptides e.g capsofungin - used IV . OD. Broad spectrum for serious systemic i nfection - candida, aspergillus. NOT for CNS/cryptococcus

19
Q

What are echinocandins NOT used for?

A

CNS/cryptococcus

20
Q

MoA of echinocandins?

A

Inhibit production of Beta1-3 glucan (part of cell wall), via . 1-3 Beta glucan synthase
Fungicidal depending on conc

21
Q

What are treatment options for candidasis infections?

A

Imidazoles e.g. clotrimazole (canesten topical)
Triazoles e.g. fluconazole (canesten oral)
Polyenes e.g nystatin - oral infections, skin, local
Systemic infection–> amphotericin B or capsofungin . (sometimes flucytosine with amphotericin)

22
Q

Treatment for vulvovaginal candidiasis VULVITIS?

A

Vulvitis - topical imidazole cream - clotrimazole 1% or 2% 2-3 times a day
OR ketoconazole cream 2% 1-2 times a day

23
Q

Treatment for vulvovaginal candidasis - VAGINAL/ vulvovaginal (Main) ?

A

10% clotrimazole cream 5g insert at night or 500mg single dose pessary at night
OR
can use oral e.g. fluconazole or itraconazole
Fluconazole 150mg single dose
Itraconazole 200mg BD for 1 day

24
Q

What are treatment options for a 12-15 year old girl with vulvovaginal candidiasis?

A

Use topical clotrimazole 1% or 2% 2-3 times a day. Not oral or intravaginal

25
Q

What are treatment options for pregnant woman with vulvovaginal candidasis?

A

NOT oral. Intravaginal clotrimazole or miconazole for at least 7 days

26
Q

Common symptoms of vaginal candidiasis?

A

Pain, itchy, creamy curd like plaques on mucosal surface / discharge.

27
Q

What is nail candidasis and symptoms?

A

Oncomycosis –> nail abnormal and discoloured, symptoms overlap with those caused by dermatophytes

28
Q

Treatment for oncomycosis?

A

hygeine, footwear, clip naisl
Initially - topical 5% laquer of amorolfine OTC for 6 months on nails, 9-12 months on toes
If topical fails or not appt - oral pulsed therapy of itraconazole 200mg BD 1 week (x2 or x3, 21 days apart)

29
Q

what is resistant candida auris?

A

Fungus similar to c.albicans (thrush) but multi drug resistance e.g. to fluconazole seen in hospitals. Can cause invasive candidiasis and blood steam infection - fungaemia

30
Q

What is aspergillosis infection? how is it . diagnosed?

A

Aspergillus sp. affects respiratory tract, heart, brain, skin - severe
Diagnosed via sputum culture(but . limited value), main ones are bronchoalveolar lavage, antigen detection (NAAT)

31
Q

Treatment for aspergillosis infection?

A

Voriconazole (triazole) but can also use liposomal amphotericin IV (polyene)

32
Q

What is dermatophytosis?

A

Filamentous fungi - epidermophyton, microsporum, tricophyton
Red scaly patch lesions on skin, nail discolouration/thickening, hair loss and scalp scarring, itchy but rarely painful

33
Q

What location of dermatophytosis is:
tinea capitis
tinea corporis
tinea pedis

A

Capitis - head scalp
Corporus - trunk
Pedis - foot -athletes foot

34
Q

Treatment for Tinea capitis?

A

Systemic griseofulvin or terbinafine + Topical imidazole / selenium sulphide shampoo / imidazole cream

35
Q

Treatment for tina corporis?

A

Topical imidazole e.g. clotrimazole etc). If not appt or fail - 1st line oral is terbinafine 250mg OD 6 weeks - 3 months for finger and 3-6 months for toes

36
Q

what is pityriasis versicolor?

A

Skin infection of yeast - malassezia furfur. Brown scaly patches
Treatment with azole creams - imidazole - ketoconaozle/ clot for 2-3 weeks.

37
Q

What is histoplasmosis?

A

Histoplasma capsulatum - inhalation of spores so lung infection.
Oral itraconazole. If severe then IV amphotericin B

38
Q

Treatment for cryptococcal infection?

A

Amphotericin B + Flucytosine IV – 2 weeks then oral fluconazole for 8 weeks

39
Q

what is aspergillus becoming resistant to?

A

Azoles

40
Q

Is candida becoming resistant?

A

Yes

PM3A (17 decks)

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