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MICRO ADYA > Microbiology 21 - Antivirals > Flashcards

Microbiology 21 - Antivirals Flashcards

1
Q

What is the mechanism of action of acyclovir?

A

Guanosine analogue that prevents elongation of DNA

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2
Q

Which viruses is acyclovir particularly useful for?

A

VZV
HSV 1 + 2

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3
Q

Which antiviral is used in HSV encephalitis?

A

High dose IV acyclovir

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4
Q

What is ganciclovir used for?

A

Pretty much only for treatment of CMV in the imunocompromised and neonates

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5
Q

What is the main side effect of ganciclovir?

A

Bone marrow toxicity

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6
Q

When is foscarnet used?

A

To treat CMV in patients where ganciclovir is contra-indicated (eg neutropaenic patients- because ganciclovir risks bone marrow failure)

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7
Q

Mechanism of action of direct acting antiviral drugs

Examples of drug classes - and which is the most common?

A

They target proteins that are specific to viruses

Examples: protease inhibitors, polymerase inhibitors, integrase inhibitors

Most common- protease inhibitors

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8
Q

How does immunomodulation help antiviral response? Examples?

A

They improve the human immune response

Examples: interferon, IVIG

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9
Q

Classification of human herpes viruses?

A
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10
Q

VZV vs Herpes Zoster

A

VZV- causes chickenpox. primary infection

Herpes zoster (aka zoster)- causes shingles when VZV is reactivated

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11
Q

Distribution of shingles in immunocompetent vs immunocompromised patients

A

Immunocompetent: in dermatomal distribution

Immunocompromised: in widespread distribution (non-dermatomal)

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12
Q

Complications of herpes zoster

A

Post-herpetic neuralgia- severe after 50 y/o

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13
Q

Indications for treatment of VZV

A
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14
Q

Why is VZV (chickenpox) in adults dangerous?

A

Increased risk of complications such as pneumonitis

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15
Q

What two main infections can HSV cause? What are the indications of treatment? And what is the treatment?

A

Encephalitis

  • affects temporal lobe, presents with altered cognitive function/consciousness
  • indications for treatment: MUST TREAT!!
  • Treatment: IV aciclovir 10mg/kg TDS, 14-21 days
    • start treatment BEFORE confirming infection with tests

Meningitis

  • parenchyma not affected
  • not as severe as HSV encephalitis- except in immunocompomirsed people
  • Indications: immunocompromised or very unwell
  • Treatment:
    • IV aciclovir for 2-3 days –> switch to oral aciclovir for 10 days OR
    • PO valaciclovir - prodrug of aciclovir (activated in liver)
      • Advantage: orally available
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16
Q

Ganciclovir MOA

A

Guanosinde analogue chain terminator. (prevents DNA elongation)

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17
Q

Foscarnet MOA

Main side effect of foscarnet

A

Non-competitive inhibitor of viral DNA polymerase

Main side effect: nephrotoxic

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18
Q

Cidofovir MOA and main side effect

A

Competitive inhibitor of viral DNA synthesis

Main side effect: nephrotoxicty

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19
Q

Who gets infected with CMV?

A

This is an opportunistic virus

cause severe disease in the immunocompromised

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20
Q

What is the best treatment for paediatric adenovirus infection?

A

Combination of cidofovir and IV Ig

21
Q

Classic histological feature of CMV

Also- where does it normally reside?

A

Owl’s eye inclusions

Normally resides dormant in monocytes and dendritic cells

22
Q

Symptoms of CMV in immunocompromised and neonates

A

immunocompromised

bone marrow suppression

retinitis- retinal exudates and haemorrhages

pneumonitis

hepatitis

colitis

encephalitis

neonates

23
Q

Tx of CMV

A

First line: IV ganciclovir or PO valganciclovir

Second line: IV Foscarnet (when ganciclovir is contraindicated eg bone marrow failure)

Third line: IV Cidofovir

24
Q

Main side effect and contraindication of gancilovir

A

Bone marrow toxicity - C/I in bone marrow transplant patients

25
Q

Disease course of EBV

A
26
Q

What is a complication of EBV in post transplant patients?

*any transplant not just bone marrow

How is it treated?

A

PTLD- post transplant lymphoproliferative disease -> predisposes to lymphoma therefore needs to be treated

Treatment: reduce immunosuppression, rituximab

27
Q

Main antivirals for influenza virus

A

Neuraminidase inhibitors

  • Oseltamivir (Tamiflu)
  • Zanamivir (Relenza)
28
Q

Which antiviral is most useful for treating RSV (bronchiolitis in children)?

A

Ribavarin - but there is a lack of good evidence for its efficacy

29
Q

What drug is given to infant groups at high risk of RSV?

A

Palivizumab

Indications:

  • preterm
  • heart or lung disease
  • SCID
  • long-term ventilation
30
Q

SARS COV2 drugs:

a) early drugs
b) Treatment of Haemophagocytic Lymphohistiocytosis (HLH)
c) Treatment of Cytokine release syndrome (CRS)- used in ICU
d) New drugs

A

a) early drugs
- remdesevir - Broad spectrum adenosine nucleotide analogue pro-drug
- Ruxolitinib: JAK1 and JAK2 inhibitor
b) Anakinra- IL-1 receptor antagonist
c) Tocilizumab- IL-6 receptor antagonist
d) new drugs :

  • Favipravir- mild to moderate disease
  • Nafamostat
31
Q

What does BK virus infection cause?

A

Primary BK infection in childhood causes minimal symptoms

but leads to lifelong carriage in the kidneys and urinary tract

Causes problems post-transplant (bone marrow and kidney)

32
Q

Tx of BK haemorrhagic cystitis

A
  • Bladder washouts
  • Reduce immunosuppression if possible
  • Cidofovir IV (+probenecid)
33
Q

Tx of BK nephropathy

A
  • Reduce immunosuppression if possible
  • IVIG

cidofovir cannot be used because it is nephrotoxic!!

34
Q

What treatment can clear chronic hep B in 3-7% of patients?

A

48 week course of pergolated interferon gamma

35
Q

Adenovirus: who does it affect and how do you treat it?

A

MOstly affects paediatric transplant patients

Treatment:

  • Cidofovir IV
  • IVIG
36
Q

Mechanism of drug resistance to aciclovr

A

Majority are due to mutation in viral thymidine kinase

37
Q

Mechanism of resistance of influenza to neuraminidase inhibitors

A

H275Y mutation

38
Q

Mechanism of resistance of CMV to ganciclovir

A

mutations in protein kinase gene (UL97)

39
Q

What are the two main types of herpes viruses and what infection do they cause?

A

HSV1: cold sores (herpes labialis)

HSV2: genital herpes. can also cause aseptic meningitis.

40
Q

What is the post exposure prophyalxis for VZV?

A

VZIG

given to immunocompromised and pregnant women

41
Q

What is the vaccine against varicella?

A

Attenuated OKA strain

contraindicated in pregnancy

42
Q

Treatment of shingles?

A

Indications: symptomatic children or (<24H OF ONSET OF RASH) healthy adult smokers, chronic lung disease, >20/40 gravid

  • aciclovir or famciclovir or valaciclovir
  • topical eye drops plus oral for olpthalmic
  • PEP- for immunocompromised
43
Q

Where does HHV6 lie dormant?

A

Lies dormant in monocytes and lymphocytes

44
Q

WHat is roseola infantum also called?

A

Exanthem subitum

45
Q

What diseases can HHV8 cause?

A

In immunocompromised:

  • kaposi’s sarcoma
  • primary effusion lymphoma
  • castleman’s disease (non-cancerous growth in lymph nodes)
46
Q

Which group of people do JC virus and BK virus infect?

A

Immunocomprimsed

47
Q

What family is JC virus and BK virus?

A

polyomaviridiae

48
Q

What does JC virus cause in immunocompromised?

A

Causes progressive multifocal leukoencephalopathy + rapidly demyelinating disease + neurological deificts

MICRO ADYA (22 decks)

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