Infection in the Immunocompromised Flashcards
What are innate defenses?
Innate immunity involves barriers that keep harmful materials from entering your body. These barriers form the first line of defence in the immune response
Examples of innate defenses?
Skin (barrier, sebum, normal flora) – e.g. burns
Mucous membranes (tears, urine flow, phagocytes)
Lungs (goblet cells, muco-ciliary escalator. Cystic fibrosis)
Interferons, complement, lysozyme, acute phase proteins
Normal commensal flora in gut – antibiotic treatment alters flora e.g. C. difficile, Candida spp.
(Extremes of age, pregnancy, malnutrition)
What is the body’s second line of defence?
Neutrophils are very important after initial breach of innate defences
i.e. less neutrophils = more infection
What can neutrophil dysfunction be divided into?
Quantitative and qualitative disorders
What characterises a qualitative neutrophil disorder?
Defect in cellular function e.g. lose ability to kill or chemotaxis
E.g. inadequate signalling
What characterises a quantitative neutrophil disorder?
- Inadequate number of mature neutrophils
- More common
E.g. cancer treatment, bone marrow malignancy, aplastic anaemia - drugs
What is an example of a qualitative neutrophil disorder?
Chronic Granulomatous Disease (CGD)
What is CGD?
- A rare, inherited immunodeficiency that affects certain white blood cells.
- Phagocytes can’t function properly
- At risk of bacterial and fungal infections
What is the classic bacteria that CGD patients are most at risk of?
Staph. aureus infections
What is neutropenia?
An abnormally low concentration of neutrophils (a type of white blood cell) in the blood
In general, what is neutropenia classified as?
<0.5x10^9/L
In neutropenic patients, what infections are most serious?
Pseudomonal infections
Treatment for neutropenic patients?
The two primary treatments for neutropenia are antibiotics to fight infection and drugs that help the bone marrow make neutrophils.
Treatment:
- Broad spectrum antibiotics e.g. Antipseudomonal penicillin +/- gentamicin
- 2nd line treatment e.g. a carbapenem
What common bacterial infections do neutropenic patients get?
- E. coli, S. aureus
- Often normal flora e.g. Coag neg staph
These patients often have lines put in, which can lead to these infections
What common fungal infections do neutropenic patients get?
Candida spp., Aspergillus spp.
What is given to neutropenic patients that help the bone marrow make neutrophils?
Granulocyte colony-stimulating factor (G-CSF) is a blood growth factor that stimulates the bone marrow to produce more infection-fighting white blood cells called neutrophils.
What is T cell deficiency?
A deficiency of T cells, caused by decreased function of individual T cells, it causes an immunodeficiency of cell-mediated immunity.
What causes congenital T cell deficiencies?
T helper dysfunction +/- hypogammaglobulinaemia
rare
What is hypogammaglobulinemia?
A problem with the immune system that prevents it from making enough antibodies called immunoglobulins.
What causes acquired T cell deficincies?
- Drugs e.g. ciclosporin after transplantation
- Steroids
- Viruses e.g. HIV
In patients with T cell deficiencies, which bacteria are they susceptible to?
Listeria monocytogenes, Mycobacteria
In patients with T cell deficiencies, which viruses– transplants are they susceptible to?
- Herpes viruses: HSV, CMV, VZV.
- Transplants
Serological testing, prophylaxis and treatment with e.g. aciclovir and ganciclovir
In patients with T cell deficiencies, which fungal infections are they susceptible to?
Candida spp., Cryptococcus spp.
Patients with T cell deficiencies are also susceptible to protozoan and parasitic infections.
One of these is cryptosporidium parvum. What is this?
One of several species that cause cryptosporidiosis, a parasitic disease of the mammalian intestinal tract.
- Oocysts shed by cattle/humans
- Faecal oral route
