September 30, 2015 - Pathogens in Immunocompromised Hosts Flashcards
When to Suspect Immunosuppression
- Prolonged course (relapse/recurrence)
- Unusual organism or infection site
- Severity is greater than expected
Phagocytic Deficits
An innate immunodeficiency.
Clinically, shows infection of recurrent abscesses with catalase positive organisms.
Common organisms for infection include S. aureus, Nocardia, and Aspergillus.
Complement Deficits
A defecit in the innate immune system.
Often leads to recurrent Neisseria infections such as meningitis.
B-Cell / Immunoglobulin Deficits
A defect in the acquired/humoral immune system.
Clinically, leads to recurrent infections (often in lungs) by encapsulated organisms such as Streptococcus pneumoniae or Haemophilus influenzae
T Cell Deficits
A defect in the acquired/cell-mediated immune system.
Leads to recurrent or opportunistic infections by many opportunistic organisms, particularly fungus and protozoa, along with viruses.
Think HIV.
Different from “Normal” Host
- Signs of inflammation are diminished. This includes no pus.
- Dual infections are common
- Lots of infectious overlap with different deficiencies
- Prophylaxis often required
- Treatment is often empiric (at least initially)
Targets of Corticosteroids
- Innate (leukocyte migration)
- Humoral (decreased B cell function)
- Cell mediated (decreased cytokine and T-cell function)
Septra
A combination of trimethoprim/sulfamethoxazole.
Targets DNA synthesis of both aerobic (trimethoprim) and anaerobic (sulfamethoxazole) bacteria.
Common Encapulated Organisms
- Streptococcus pneumoniae*
- Neisseria meningitiditis*
- Haemophilus influenzae*
Chemotherapy and Immune Deficiency
Can cause febrile neutropenia.
Need to put patients on prophalactic antibiotics.
Febrile Neutropenia
Often a complication of chemotherapy when it is myelosuppressive.
This is a medical emergency and you must go to the hospital ASAP.
