Microbiology 13 - Opportunistic viral infection Flashcards
What system is used to classify viruses?
Baltimore classification system
What class of viruses form latent infections?
DNA viruses
How is most viral serology performed?
Indirectc ELISA
Recall 3 reasons for immunosuppression
- Solid organ transplant
- Human stem cell transplant (short term, or long term if they have significant GVHD)
- HIV/AIDS
Recall 4 types of immunosuppressing drugs
- Steroids
- Calcineurin inhibitors
- Anti-proliferative agent (eg. Azothioprine/ mycophenolate)
- Antibodies
What is the most important opportunistic virus in transplant patients?
CMV
What virus causes multifocal leukoencephalopathy?
JC virus
What is a common re-activator of latent HSV?
Stressful situations
What is HHV4?
EBV
What is HHV8?
Kaposi’s sarcoma associated herpesvirus
What drug would you give to someone who has CMV AND is immunosuppressed?
Valganciclovir
For which hepatitis viruses are there vaccines?
Hep A and B
Why is adenovirus particularly problematic in post-bone marrow transplant children?
You get disseminated disease
What is the treatment for disseminated adenovirus?
Cidofavir
In which patients does JC virus cause PML?
AIDS patients
What two conditions can BK virus cause in the immunosuppressed?
- *Stem cell transplant:** Haemorrhagic cystitis
- *Renal transplant:** Nephropathy
If have a patient with haematuria and lots of clots, think about this
What disease does parvovirus cause in a chronically immunosuppressed patient?
Anaemia
In renal transplants, is risk of CMV transmission when the donor or recipient is positive?
Donor is pos as recipient has never seen CMV before
In Human Stem Cell Transplants, is risk of CMV transmission when the donor or recipient is positive?
Donor is neg (recipient is pos) as patient with CMV has immune system replaced with one that is CMV-naive
Describe the pattern of symptoms caused by varicella infection in the immunocompromised
Pneumonitis, encephalitis and hepatitis
In neonate: purpura fulminans
What is the most common malignancy caused by EBV?
Post-transplant lymphoproliferative disorder
What is the most common clinical syndrome caused by CMV infection in immunocompromised? HOw is this idff to immunocomptenet?
immunosuppressed: Retinitis
immjnocompetent: tends to be asymptomatic or can cause infectious mononucleosis
What CMV prophylaxis is offered, and to whom?
Ganciclovir
Given to all transplant patients
Recall which infections affect HIV patients?
What is HHV3?
VZV
Solid organ transplant vs stem cell transplant: viral infections
Solid organ transplant:
- viral reactivation occurs >1month after
Stem cell transplant:
- viral reactivation occurs within 1 month as there’s extensive immunosuppression
What are the 3 sources of infection following transplant?
Are herpes viruses DNA or RNA viruses?
DNA viruses
What is a defining feature of herpes viruses?
they have a tendency to reactivate in immunocompromised patients
and persists for life in the host
Where do VZV, EBV and CMV cause latent infection?
VZV: dorsal root ganglion
EBV: B cells
CMV: dendirtic cells and monocytes
Which HHV’s tend to reactivate in BM transplant patients?
HSV, HHV6 and HHV7
HSV1 vs HSV 2
HSV1- oral/ mucocutaneous
HSV2- genital
Indications for HSV prophylaxis
- CD4 <200 in HIV/AIDS
- Bone marrow:
- 1 month (until engraftment)
- Solid organ:
- 3-6 months prior to transplant
- And if treated for rejection
When does VZV present?
- Usually a late complication in post-transplant
- Can be an early manifestation in HIV:
- → indication for HIV testing particularly in young person
How does VZV present in immunocmpmroised?
Really severe
Multi-dermatomal
Can disseminate
→ associated with high mortality
What is PTLD?
post-transplant lympho-proliferative disorder
Immunosuppression used in organ transplants
→ breakdown of immunosurveillance keeping B cells and EBV in check
→ polyclonal expansion of B cells
→ predisposes to lymphoma
What is the pathological hallmark of CMV?:
Owl’s eye appearance on lung pneumocytes
due to inclusion bodies
How much immunosuppression is needed post-transplant in SOT vs HSCT?
- Solid Organ Transplant
- requires lifelong immunosuppression
- Haematological Transplant
- intense immunosuppression
- for a relatively short period of time
Kaposi sarcoma histology
spindle cell proliferation
neo-angiogenesis
inflammation
and oedema
