(FE) Week 12 Infx in Immunocompromised Populatn

Question 1

How can anatomical and physical barriers be broken down for infx to occur?

Answer 1

1) Skin
- Wounds, burns, IV plugs, drug allergies

2) Ciliary clearance and airway protection
- Intubation, tracheostomy
- COPD
- Depressed conscious level

Question 2

What are some conditions where neutropenia will occur?

Answer 2

1) Bone marrow failure
- Leukemia, lymphoma, aplastic anemia

2) Drug
- Chemotherapy, PTU, Valgancyclovir

Question 3

What infx are more probable if a px have neutropenia?

Answer 3

• Gram-neg rod infc
  ~ E. coli, Klebsiella
  ~ S. aureus
  ~ Pseudomonas
• Candida
• Aspergillus (if neutropenia is prolonged for 2-3 weeks)

Question 4

What is the management of neutropenia?

Answer 4

• Monitor fever
• Early Ab treatment while febrile
• Avoid procedures that can introduce bacteremia
• Px isolation

Question 5

What instances would there be a decrease in antibody?

Answer 5

• Multiple myeloma (B cell unable to produce Ab)
• Rituximab (monoclonal Ab removes B cells, especially in lymphoma)

Question 6

What are some ways to protect the cellular immunity?

Answer 6

• Antiviral prophylaxis (eg Herpes zoster)
• PPE
• Vaccination
• Food hygiene
• Cohorting
• No gardening, fresh flowers or mouldy areas
  ~ For px infected with aspergillus, mucor, pneumocystis jirovecii
• Trimethoprim/Sulfamethoxazole
  (Bactrim) prophylaxis
  ~ For toxoplasma infx

Question 7

What are the steps in hematopoetic stem cell transplantation?

Answer 7

1) Eradicate patient’s own stem cells
- Using high dose chemotherapy

2) Infusion of new stem cells
- Takes 2 weeks to see graft function

3) Prevention of graft vs host disease
- Through immunosuppression of T cells

Question 8

After graft infusion, which cells grow back first?

Answer 8

Neutrophils (from 0) -> B/T cells (from 0)

Plasma and dendritic cells decrease then increase again

Question 9

What are the 3 phases after HSCT?

Answer 9

1) Pre-engraftment
- 3 weeks after stem cell infusion
- Neutropenia, no neutrophils at all
~ Px mostly at risk of bacterial infx

2) Immediate post-engraftment
- 3 weeks - 3 months
- Start to see increase in graft cells
- Neutrophil counts up but not for B/T cells
~ Px at risk of viral and fungal infx (eg CMV, aspergillus)

3) Late post-engraftment
- After 3 months

Question 10

What is the px care after HSCT?

Answer 10

• Positive pressure room
• Antibiotic and antifungal prophylaxis
• Avoid visitors, fresh flowers and raw food
• Strict hand hygiene and infx protocol

Question 11

What are the phases after solid organ transplantation?

Answer 11

1) Immediate post-transplant
- Intense, high dose IV immunosuppression
~ To prevent T cell attack on transplant
- Px still has neutrophils so still able to fight against common bacterial infx
- Infx mostly against Abx-resistant species, foreign object infx

2) <90 days
- Continuous intense immunosuppression orally
~ Decreased dose
- Common infx against C. diff, CMV, HBV, cryptococcus

3) After 90 days
- Lowest maintenance immunosuppression orally
- Infx usually community-acquired pneumonia, aspergillus, viruses

Question 12

What is the care after solid organ transplant?

Answer 12

• Single room
• Strict infx control
• No sick visitors
• Cooked food only
• Safe living counselling

Question 13

What are the opportunistic infections that can occur at various CD4+ T cell levels?

Answer 13

<50: CMV, Mycobacterium avium complex

<100: Candida, Cryptococcus, Toxoplasmosis, Histoplasmosis, Penicillosis

<200: Pneumocystis

Any: TB, Herpes

Question 14

How to prevent further infections when a px has HIV?

Answer 14

1) Trimethoprim/Sulfamethoxazole (Bactrim)
- To prevent PCP and toxoplasma

2) Clarithromycin/Azithromycin
- Prevent Mycobacterium avium complex
- If antiretroviral medication is initiated, no need to give prophylaxis

No need for single cohort room