Week 10 - Immunocomprimised host Flashcards
Define immunocomprimised host
-A host in a state in which the immune system is unable to respond appropriately and effectively to infectious microbes
Describe the types of infections which would indicate underlying immundeficiency
-Severe, Persistant, Unusual and Recurrent
What is the cause of a primary immunodeficiency?
-An intrinsic cause such as gene mutation in any immune genes
How old are the patients diagnosed with primary immunodeficiency?
-Presents within first months of life
Who is primary immunodeficiency most common in and why?
-Males because it is x-linked
What is common variable immunodeficiency?
-Inability of B cell maturation
What malignancy is associated with primary immunodeficiencies?
-lymphoma/gastric carcinoma
Besides malignancy, what other type of condition is associated with immunodeficiency?
-Autoimmune
Describe the management of primary immunodeficiencies
- Promp/prophylactic abx
- Ig replacement therapy if appropriate
What is the cause of chronic granulomatous disease?
-Lack of respiratory burst in neutrophils leading to prolonged and recurrent infections
NAme a T cell deficiency
-DiGeorge
What are the signs of severe combined ID?
- Failure to thrive
- Deep skin/organ abscesses
- Decreased lymphocytes
What is secondary immunodeficiency?
-Decreased production of immune components due to malnutrition, infection, liver disease, lymphoproliferative diseases and splenectomy
How does lymphoproliferative disease lead to immunodeficiency?
- Invasion of lymph nodes
- Chemotherapy destroying mucosal barriers and suppressing WBC production
What type of bacteria are asplenic patients susceptible to? why?
- Encapsulated
- Spleen is site of ab production and ab needed to opsonise encapsulated bacteria for destruction
- Also spleen houses macrophages
How are asplenic patients managed?
- Carry a card or bracelet
- Penicillin prophylaxis and immunisations
To what types of organisms are T cell deficiencies susceptible to?
-Viruses and fungi
To what types of organisms are B cell deficiencies susceptible to?
-Bacteria and fungi
What is a common fungus which affects immunocomprimised hosts?
-aspergillus
What is CRP, where is it produced and what triggers its production? What is its function in the innate immune response?
- Creatine reactive protein
- Liver
- IL6 secreted by monocytes and macrophages
- Bind to phosphocholine on dead/dying cells and promotes apoptosis by activating complement
Why is it essential to start treatment before you have evidence of infecion in an immunocomprimised host?
-Should be treated as an acute medical emergency if infection is suspected as deterioation can happen quickly
Why do fungi not respond to standard antibiotics?
-Do not have the cellular targets which abx act against eg no cell wall, protein synthesis more complex etc
What infection does varicella zoster cause and what does it mean if the Ab is present in serum?
- Chicken pox
- There has been previous exposure or vaccination
How is varicella-zoster transmitted?
-Inhalation droplets
Where does varicella-zoster remain latent?
-In cutaneous neurones
List some virulence factors of staph aureus
- Coagulase positive -> able to coagulate blood around itself for protection against phagocytosis
- Streptokinase to breakdown fibrin and aid spread
- Exotoxins eg enterotoxin causes gastroenteritis
How are immunocomprimised hosts affected by infection?
-Increased frequency and severity
