Microbiology - Immunocompromised Hosts

Question 1

What are some reasons why someone may be immunocompromised?

Answer 1

Genetic:
- e.g. immunodeficiency syndromes)

Acquired:
- Transplant (Solid organ/SCT)
- Chronic conditions (e.g. AIDs)
- Iatrogenic: chemotherapy/corticosteroids

Question 2

How do viral infections present different in an immunocompromised host?

Answer 2

• Disseminated
• Different organs
• More severe
• Oncogenic (HHV8 = Kapsi sarcoma)

Question 3

Why are pathogens of specific concern in an immunocompromised host?

Answer 3

• Do not cause disease in immunocompromised host
• Cause more severe/disseminated disease in immunocompromised
• Require consideration of prophylaxis/treatment in immunocompromised pts

Question 4

What are some viruses of specific concern in an immunocompromised host?

Answer 4

• Herpesviridae (causes latent infection): CMV, CBV, HSC, HHV8, VZV
• Polyomaviridae: JC virus, BK virus
• Respiratory viruses: Influenza A + B, Parainfluenza (1,2,3,4), respiratory synctial virus (RSV), adenovirus, MERS coronavirus
• Hepatitis viruses: A (normally vaccinate), B,C,E (increased risk of chorionicity

Question 5

What are some fungi of specific concern in an immunocompromised host?

Answer 5

• Candida
• Cryptococci
• Aspergillus
• Dermatophytes
• Mucormycosi

Question 6

What are some consequences of immunocompromise?

Answer 6

Unusual organisms:
- HIV = microsporidium
- CF = Burkholderia cepacia
- Anti-TNFα = JC virus

Unusual site:
- HIV = CMV colitis, oesophageal candidiasis
- Sickle cell = salmonella septic arthritis

Prophylaxis:
- Vaccination pre-splenectomy
- Cotrimoxazole in HIV