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PM3A: Autumn > Infections Lecture 6: Fungal infections and anti fungal drugs > Flashcards

Infections Lecture 6: Fungal infections and anti fungal drugs Flashcards

1
Q

What is a fungus

A

Single celled or multicellular organism

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2
Q

Give examples of single celled fungus organisms

A

Candida SPP, Cryptococcus

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3
Q

Give examples of filamentous, mould, multicellular organisms

A

Aspergillus SPP

Dermatophytes

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4
Q

What is the fungal cell wall normally made of

A

Beta 1,3 glucans

Beta 1,6 gluons

Chitin

Ergosterol

Beta 1,3 glucan synthase

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5
Q

State all the main anti fungal drugs PAAEFG or FAGPAE

A

POLEYENES (main one)

AZOLES (main one)

ALLYLAMINE (main one)

ECHINOCANDINS

FLUCYTOSINE

GRISEOFULVIN

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6
Q

Give an example of a Polyene, its route/indication, spectrum and side effects

A

Example: Amophotericin B, NYSTATIN

Route:
Oral, not toxic: Oral candida
IV, highly toxic: life threatening cryptococcal meningitis

Spectrum: Broad

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7
Q

What is the polyene mechanism of action

A

Binds to ergosterol to form pores in plasma membrane

Leaks out K+ and Mg2+

Lysis- cell death

Fungicidal

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8
Q

What are the two types of Azoles that are available

A

Imidazole

Triazole

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9
Q

Give examples of imidazole and the route

A

Miconazole (Daktarin)

Clotrimazole (canesten cream)

Ketoconazole (nizoral cream/shampoo)

Route: topical for superficial mycoses

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10
Q

Give examples of Triazoles and the route

A

Fluconazole (capsules, liquids, IV, systemic)

Itraconazole (sporanox, capsules, liquid, IV)

Posaconazole (tablet or suspension)

Route: oral or systemic

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11
Q

What is the mechanism of action of azole

A

Inhibition of lanosterol 14 alpha-demethylase (cytochrome P450) this interrupts ergosterol biosynthesis

Disrupts plasma membrane and acts as fungistatic

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12
Q

Give an example of Allylamines, its spectrum

A

Example: TERBINAFINE (lamisal)- fungal nail infection

Spectrum: mainly dermatophytes

Mechanism:

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13
Q

What is the mechanism of action of Allylamine

A

Inhibits squalene epoxidase which inhibits the production of lanosterol from squalene in ergosterol biosynthesis

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14
Q

Give an example of Echinocandins, its route and spectrum/indication

A

Lipopeptides (caspofungin)

Route: Intravenous (1 per day)

Spectrum: BROAD against candida, aspergillus

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15
Q

What is the mechanism of action of Echinocandins

A

Inhibition of production of Beta 1-3

Gluten (part of cell wall) 1-3

Beta glucan synthase- fungicidal

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16
Q

Give a type of flucytosine, a route, spectrum/indication

A

Type: Fluoropyrimidine

Route: oral or IV

spectrum: can be used with other drugs against severe cryptococcal or candida infections

17
Q

What is the mechanism of action of flucytosine

A

Converted into 5-FU which disrupts RNA and DNA synthesis (fungistatic)

18
Q

Give a type of Griseofulvin, route and spectrum

A

Type: Benzofuran

Route: Oral (tablets or suspensions)

Spectrum: normally dermatophytes like Tinea Capitis

19
Q

What is the mechanism of action of Griseofulvin and side effects

A

Binds to polymerised microtubules to inhibit mitosis (half growth)

Side effects: Rash, urticaria, nausea, vomtiing, anorexia

20
Q

In candidiasis, what is the common causative organism and common cause

A

C.albicans

Cause:
Broad spectrum antibiotics
Immunodeficiency

Localised thrush: due to balance upset

21
Q

What are the symptoms of candidiasis and in immunocompromised patients

A

Usually localised: skin, mucosal, vaginal, oral thrush

Pain
Itching
Creamy curd like plaques on mucosa surface
Itching

Immunocompromised:
pharyngitis
oesophagi’s
dysphagia with weight loss and sepsis

22
Q

How do you diagnose candidasis

A

clinical features

Laboratory culture

23
Q

What is the cause of Aspergillosis (fungi) and the symptoms?

A

Aspergillus Spp
Affects the respiratory tract
Severe: affects heart, brain and skin

Symptoms: wheezing, breathlessness, fatigue, cough (mucus plugs), feeling unwell

24
Q

How do you diagnose Aspergillosis?

A

Sputum Culture- limited value

Bronchoalveolar lavage

Antigen detection, NAAT detection

25
Q

How do you treat Aspergillosis

A

Voriconazole

Itraconazole, caspofungin, posaconazole - alternatives: bronchodilators and steroids

Isolation for neuropathic pain

26
Q

What are the three types of Dermatophytosis

A

Epidermophyton

Microsporum

Trichophyton

27
Q

What are the symptoms of Dermatophytosis

A

Red scaly patch like lesions (skin)

Nail discolouration and thickening

Hair loss and scarring (scalp)

Itchy but painful

28
Q

What is the clinical diagnosis of dermatophytosis on different locations of infection site called (3)

A

Tinea Capitis (head scalp)

Tinea Corporis (trunk and leisions)

Tinea Pedis (Athletes foot)

29
Q

What is pityriasis versicolor caused by, its symptoms, diagnosis and treatment

A

Malassezi fur fur

Brown Patchy sections

Skin culture scraping

Topical anti fungal (Imidazole): ketoconazole
Oral itraconazole or fluconazole

30
Q

What is histoplasmosis caused by, transmitted by, and symptoms, diagnosis, treatment

A

Histoplasma capsuatum

Spore inhalation

Lung infections: flu like symptoms
Chronic infections: TB resemblance

Diagnosis: blood samples and cultures

Treatment: oral intraconazole
Severe: IV amphotericin B

31
Q

What normally causes cryptococcal infection

A

Cryptococcus Neoformans (inhalation)

Lung infection (pneumonia)

Cryptococcus meningitis in HIV and AIDS

32
Q

What are the symptoms, diagnosis and treatment of cryptococcal infection

A

Symptoms:
Fever, fatigue, dry cough, headache, nausea, confusion, chest pain, skin rash, blurred vision

Diagnosis:
Blood test, sputum and urine screening

Treatment:
Amphotericin B and flu cytosine (2 weeks IV)
Oral fluconazole: 8 weeks

33
Q

What are the four mechanisms of resistance in fungi same as bacteria

A
  1. Altered drug metabolism
  2. Efflux Pumps
  3. Change in protein target
  4. Prevention of drug entry

PM3A: Autumn (20 decks)

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