Infections in the immune compromised host Flashcards
Define immunocompromised host
a patient who does not have the ability to respond to an infection because their immune system is weakened
can be because of an immunodeficiency disorder or other disease or as the result of administration of immunosuppressive drugs/radiation
General causes of immunodeficiency in a host
primary immunodeficiency
acquired immunodeficiency (HIV)
diabetes mellitus
leukaemia/lymphoma
transplantation
splenectomy
chemotherapy
radiation
What pathogen factors influence infection?
virulence factors
cell wall
capsule
enzymes
What environmental factors influence infection?
geographic factors
medical devices
hospital
What host factors influence infection?
innate immunity:
- pathogen recognition receptors
- IFNalpha, IFNbeta, NK cells
- complement, skin (anatomic barrier)
phagocytes:
- macrophages
- neutrophils
cytokines:
- IL-1
- TNF
chemokines
cellular immunity:
- B-cells
- T-cells
Name some encapsulated bacteria
strep pneumoniae
N.meningitidis
H.influenzae
salmonella
giardia (parasite)
cryptosporidia
What classifies as neutropenia, severe neutropenia and prolonged neutropenia?
neutropenia = <2x10^9/L
severe neutropenia = <0.510^9/L
prolonged neutropenia = >21 days
Neutropenia causes
Congenital (eg. Fanconi’s anaemia)
Immune-mediated (eg. SLE, Felty’s)
Infection (eg. sepsis, HIV, influenza)
Bone marrow failure (myelodysplasia, leukaemia, lymphoma)
Stem cell transplantation
Chemotherapy
Radiation
Neutropenic sepsis bacterial causes
Staphylococcus aureus
Coagulase negative staphylococci
Viridans streptococci
Enterococcus
Escherichia Coli, Enterobacter
Pseudomonas aeruginosa
Klebsiella Spp
Listeria
Neutropenic fever fungal causes
Aspergillus spp
Pneumocystis Jirovecii (PCP)
Fusarium
Zygomycosis
Candidiasis
Neutropenic fever viral causes
Herpes simplex
CMV
Varicella zoster virus
Respiratory syncytial virus (RSV)
Parainfluenza viruses
Influenza A+B
Adenoviruses
Primary prevention of infection
prevent or reduce exposure
immunisation
Secondary prevention of infection
Chemoprophylaxis (antibiotics, antivirals)
Tertiary prevention of infection
effective treatment
physiotherapy
Spleen functions
Largest lymphoid organ
a) immune-regulatory (B and T cell memory)
b) immune clearance (opsonic antibody production, complement production)
c) phagocytosis (removal of micro-organisms)
d) immune surveillance (B and T cell trafficking, delivery of antigenic information)
