Crash Course Immunocompromised + Influenza Flashcards

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1
Q

Which organisms are patients with splenectomy susceptible to?

A

encapsulated organisms- NHS
Neisseria
Haemophilus
Streptococcus

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2
Q

What are 2 microbiological consequences of immunocompromise?

A

Infection with unusual organisms

Infection in unusual sites

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3
Q

Name 2 unusual organisms and 2 unusual sites of infection seen in HIV patients

A

Organisms:
Microsporidium: GI infection exclusively seen in HIV
MAC

Sites:
CMV colitis
Oesophageal candidiasis

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4
Q

What unusual organism are patients with CF susceptible to? What is the significance of this?

A

Burkholderia cepacia

CI to lung transplant

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5
Q

What organism causes an unusual site of infection in sickle cell disease patients?

A

Salmonella septic arthritis

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6
Q

What unusual organism are patients on monoclonals such as anti-TNF alpha susceptible to?

A

JC virus

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7
Q

What prophylactic measures can be taken for immunocompromised?

A

Pre-splenectomy: Vaccination against meningitis + pneumonococcus

HIV: Co-trimoxazole if CD4 <200

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8
Q

What is caused by reactivation of JC virus?

A

Progressive multifocal leukoencephalopathy

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9
Q

What is JC virus AKA?

A

Human polyomavirus 2

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10
Q

How many serovars of influenza? Which is worst?

A

4 serovars (C+D not clinically relevant)
A worse than B- more likely to cause pandemic

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11
Q

What 3 characteristics are required for a virus to cause a pandemic?

A

Novel antigenicity

Replicates efficiently in human cells.

Transmit efficiently between people.

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12
Q

What results in novel antigenicity?

A

Antigenic drift
Antigenic shift

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13
Q

What is antigenic drift?

A

Accumulation of mutations over time.

Error prone replication process, slightly different primary sequence for some of the proteins, happens relatively frequently, small changes accumulate

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14
Q

Why are new vaccines to influenza required each year?

A

Antigenic drift
Leads to production of new epidemic strain every year
Pre-formed antibodies from last exposure are not so effective.

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15
Q

What is antigenic shift?

A

Recombination of genomic segments of 2 co-infecting flu strains→ leads to rapid antigenic change+ production of new viral strain (shift)

Allows exchange of RNA segments between human + animal strains

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16
Q

Why does antigenic shift not happen often?

A

Rare for an organism to be co-infected with 2 strains of influenza

Often recombination produces nonsense

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17
Q

What is the natural reservoir of influenza A viruses?

A. Pigs

B. Chickens

C. Ducks

D. Tigers

A

Ducks

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18
Q

How is the viral genome of influenza composed?

A

8 “chunks” of RNA

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19
Q

What is Haemagglutinin? What is its function?

A

Protein on surface of influenza
Allows ENTRY: binds to sialic acid, cleaved by tryptase on surface of cells in lungs

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20
Q

What is haemagglutinin especially prone to? What is the significance of this?

A

Prone to antigenic DRIFT
Target this protein in yearly vaccine

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21
Q

What is Neuraminidase? What the function of Neuraminidase?

A

Protein on surface of influenza virus
Allows EXIT: Cleaves sialic acid
Facilitates viral release

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22
Q

What is neuraminidase more prone to?

A

Antigenic SHIFT process

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23
Q

What technique can determine virus and strain of influenza?

A

RT-PCR
(Reverse transcription polymerase chain reaction)

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24
Q

What is the most commonly used influenza antiviral?

A

Oral Oseltamivir
Neuraminidase inhibitor
Prevents viral release + thus replication + infection of other cells

Others: Inhaled Zanamivir + IV Peramivir

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25
Q

How do normal antivirals and ‘val-antivirals’ differ?

A

Usually same drug
Val- increases bioavailability + resistance to first pass metabolism
Can be taken less often to get up to therapeutic dose
Can be taken orally

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26
Q

What is the stepped treatment of HSV or VZV? (if previous step ineffective)

A
  1. Acyclovir
  2. Foscarnet
  3. Cidofovir
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27
Q

What is the stepped treatment of CMV or EBV?

A
  1. Ganciclovir
  2. Foscarnet
  3. Cidofovir
28
Q

For non-herpes viral infections e.g. Adenovirus, what anti-viral should be used? What are the disadvantages of this?

A

Cidofovir
“Dirty drug”: Nephrotoxic, Ocular toxicity + BM suppression

29
Q

What are the manifestations of HSV1?

A

Oral herpes: Herpes labialis
Initially may be HSV gingival-stomatitis in mouth
HSV encephalitis

30
Q

What does reactivation of HSV1 usually cause?

A

Isolated vesicles + cold sores

31
Q

What are the manifestations of HSV2?

A

Genital herpes
HSV meningitis

32
Q

Which types of HSV virus infections are AIDS defining illnesses?

A

HSV oesophagitis, colitis or rarely pneumonitis

33
Q

What is eczema herpeticum?

A

Disseminated herpes infection in those with atopic dermatitis
Usually kids with eczema

34
Q

What is herpetic whitlow?

A

Herpes on the finger
Common in HCPs

35
Q

In which patients is disseminated cutaneous herpes seen?

A

Immunocompromised

36
Q

How does VZV commonly present?

A

In children with fever, malaise + rash
Rash starts on face, descends
Macules -> Papules -> Vesicles

37
Q

List 4 serious complications that can arise from VZV in adults/ immunocompromised

A

Pneumonitis
Encephalitis
Myocarditis
DIC

38
Q

What is caused by reactivation of VZV?

A

Herpes zoster: Shingles- dermatomal rash

39
Q

What is Ophthalmic herpes zoster?

A

Shingles of V1 (1st branch of trigeminal nerve)
Can damage retina
Specific sign: Hutchinson sign- vesicles on tip of nose
Emergency- send to ophthalmologist

40
Q

What is Ramsay Hunt syndrome?

A

Shingles affecting facial nerve
Ear pain
Facial paralysis
Vesicles usually in ear
Requires prompt Tx

41
Q

Which medication should NOT be given in VZV infection?

A

Ibuprofen
Esp. in children
Increases risk of secondary skin infections + necrotising fasciitis

42
Q

Name one complication of shingles

A

Herpetic neuralgia
Pain in distribution of that dermatome

43
Q

How does Epstein-Barr virus present?

A

Presents with infectious mononucleosis:
Fever
Pharyngitis
Lymphadenopathy (usually symmetrical, posterior cervical chain)
Hepatitis
+/- Splenomegaly

44
Q

Give 3 investigations for EBV

A

EBV serology
Atypical lymphocytes
Heterophile antibody (monospot test)

45
Q

Name 2 infections other than EBV that can cause infectious mononucleosis

A

CMV
Toxoplasmosis

46
Q

What is the management of EBV?

A

Not much evidence for using antivirals

Avoid contact sports

Avoid alcohol (have hepatitis)

47
Q

If very fulminant EBV, what drug may be considered?

A

Ganciclovir

48
Q

Why must high contact sports be avoided in EBV?

A

Splenomegaly- increases risk of splenic rupture

49
Q

What malignancy is EBV associated with?

A

Nasopharyngeal carcinoma
Burkitt’s lymphoma

50
Q

Where does EBV remain dormant?

A

B cells

51
Q

What occurs in EBV post-transplant lymphoproliferative disease?

A
  1. Immunosuppression for transplant
  2. Once immunosuppressed lose surveillance of EBV
  3. Leads to pre-lymphoma state
  4. Needs intervention or will progress to lymphoma
52
Q

How does Cytomegalovirus present?

A

Typically Asymptomatic
or
Infectious mononucleosis picture

53
Q

Where does Cytomegalovirus live dormantly? How is it visualised?

A

Monocytes + Dendritic cells

Owl’s Eye inclusion bodies

54
Q

Give 4 manifestations of CMV reactivation in immunosuppressed individuals

A

Pneumonitis
Retinitis
Colitis
Encephalitis

55
Q

What is firstline treatment for CMV?

A

Ganciclovir / Valganciclovir

56
Q

How does CMV pneumonitis appear on imaging?

A

ground glass appearances
multifocal
widespread

57
Q

Give 1 feature of CMV retinitis on fundoscopy

A

Cotton wool spots difusely

58
Q

What are the manifestations of HHV6 and HHV7?

A

Principally causes ROSEOLA

very very rarely encephalitis

59
Q

How does HHV8 manifest?

A

Only seen in immunosuppressed, esp. HIV
Lymphoproliferative diseases:
Kaposi’s Sarcoma
Castleman disease
Primary effusion lymphoma

60
Q

Where do Kaposi Sarcoma lesions occur?

A

Skin
Internally esp. resp + GI tract: can haemorrhage severely

61
Q

What is the treatment of kaposi sarcoma?

A

Treat immunosuppression + immune system should clear the cancer

62
Q

Give 4 manifestations of Adenovirus in immunosuppressed individuals

A

Pneumonitis/ pneumonia
Haemorrhagic cystitis
Meningioencephalitis
Colitis

63
Q

What occurs in JC virus in immunocompromised?

A

Can reactivate in brain causing Progressive Multifocal Leukoencephalopathy
(resistant to antivirals)

64
Q

In which patients is BK virus worrying?

A

Transplant patients

65
Q

What does BK virus cause in renal transplant and bone marrow transplant patients?

A

Renal: BK virus infects transplanted kidney: Nephropathy

BM: Haemorrhagic cystitis