Infection 9 The Immunocompromised Host Flashcards
What is an immunocompromised host?
State in which the immune system is unable to respond appropriately and effectively to infectious microorganisms
How is primary immunodeficiency caused?
Congential
Due to intrinsic gene defect - missing cell or protein or non functional components
How is secondary immunodeficiency caused?
Acquired
Due to underlying disease/treatment
Decreased production/function of immune cells
Increased loss or catabolism of immune cells
When should you suspect immunodeficiency?
SPUR
Severe
Persistent
Unusual
Recurrent
What are the 10 warning signs for primary immunodeficiency in children?
4+ new ear infections in 1 year
2+ serious sinus infections in 1 year
2+ months on antibiotics with little effect
2+ pneumonias in 1 year
Failure to gain weight or grow normally
Recurrent, deep skin or organ abscesses
Persistent oral thrush or fungal infection on skin
Need IV antibiotic to clear infection
2+ deep seated infections
Family history of PID
What are the 10 warning signs for primary immunodeficiency in adults?
2+ new ear infections in 1 year
2+ serious sinus infections in 1 year
Recurrent pneumonias
Chronic diarrhoea with weight loss
Recurrent, deep skin or organ abscesses
Persistent thrush or fungal infection on skin
Need IV antibiotic to clear infection
Infection with normally harmless bacteria
Family history of PID
Recurrent viral infections
What are the limitations of the 10 warning signs of PID?
General use
Different presentations + defects per patient
Patients with non-infections manifestations
What defects can cause immunodeficiency?
Antibody defects
T cell defects
Phagocytic defects
Types of defects in antibodies causing immunodeficiency
Defect in B cell development
Defect in antibody production
Types of defects in T cells causing immunodeficiency
Combined B + T cell defects
T cell defects
Types of phagocytic defects causing immunodeficiency
Defects in respiratory burst
Defects in fusion of lysosome/phaagosomes
Defects in neutrophil production + Chemotaxis
What are types of unusual presentation?
Site of infection
Type of microorganism
What defect does immunodeficiency onset < 6 months suggest?
T cell defect
Phagocyte defect
What defect does immunodeficiency onset 6 months to 5 years suggest?
B cell defects
Phagocyte defects
What defect does immunodeficiency onset > 5 years suggest?
B cell defect
Secondary immunodeficiency
Types of Management of PID
Support treatments
Specific treatment
Comorbidities
Supportive treatment of PID
- Infection prevention - prophylactic antimicrobial
- Treat infections promptly and aggressively
- Nutritional support
- Avoid live vaccines
- Use UV-irradiated CMV negative blood products only
Specific treatment of PID
Regular immunoglobulin therapy
Haematopoietic stem cell therapy
Comorbidities management of PID
Autoimmunity + malignancies
Organ damage
Avoid non essential exposure to radiation
What immunodeficiency conditions are caused by defects in antibody production?
CVID - Common variable immunodeficiency
Selective IgA deficiency
What form of primary antibody deficiency requires treatment?
CVID - common variable immunodeficiency
What immunodeficiency conditions are caused by defects in B cell production?
X-linked agammaglobinaemia - no B cells
What immunodeficiency conditions are caused by defects in B and T cells?
SCID - Severe combined immunodeficiency
What immunodeficiency conditions are caused by defects inT cells?
Di George syndrome
What immunodeficiency conditions are caused by defects in respiratory burst?
CGD - Chronic granulomatous disease
What immunodeficiency conditions are caused by defects in fusion of lysosome/phagosomes?
Chediak-Higashi syndrome
Presentations of chronic granulomatous disease
Pulmonary aspergillosis - long term lung infection
Skin infections
Halo signs in HRCT scan
Age of onset which suggests T cell or phagocyte defect
< 6 months
Age of onset which suggests B cell or phagocyte defect
6 months - 5 years
Age of onset which suggests B cell defect or secondary immunodeficiency
> 5 years
What conditions can immunoglobulin replacement therapy be used for?
Hyper IgM syndrome
X linked agammaglobinaemia
Common variable immunodeficiency
Different formulations of immunoglobulin replacement therapy
IvIg - intravenous
ScIg -subcutaneous
What causes a decreased production of immune components?
Malnutrition
Infections e.g. HIV
Liver diseases
Haematological malignancies
Splenectomy
Therapeutic treatments
What causes a increased loss of immune components?
Burns
Protein-losing conditions e.g. nephropathy, enteropathy
What are tonsils mostly made with?
B cells
Disadvantage of immunoglobulin replacement therapy
Life long treatment
Why are patients with haematological malignancies more susceptible to infections?
- Chemotherapy induced neutropenia
- Chemotherapy induced damage to mucosal barrier
- Vascular catheter - breach of innate immune response > bacteria can enter
Lab investigations when there suspicions of T cell deficiency
FBC - lymphocyte count
T cell function tests
Lab investigations when there suspicions of antibody/B cell deficiency
Immunoglobulins
What form of primary antibody efficiency doesn’t require treatment?
Selective IgA deficiency
What is the most common cause of T cell defect?
Di George Syndrome
Which long term treatment would you suggest for a patient with primary antibody deficiency?
Immunoglobulin replacement therapy
What causes X linked agammaglobulinaemia?
Defect in B cell development - no B cells
What causes common variable immunodeficiency?
Defect in antibody production
What causes selective IgA deficiency?
Defective antibody production
What causes hyper IgM syndrome?
Defect in antibody production
What causes severe combined immunodeficiency?
Combined B + T cell defects
What causes Di George syndrome?
T cell defects
What causes chronic granulomatous disease?
Defects in respiratory burst
Phagocytic defect
What casues Chediak Higashi syndrome
Defect i the the fusion of lysosome + phagosomes
