infection in the immunocompromised Flashcards
what is the background of infections in an immunocompromised host?
there is a problem with some part of the immune system and disruption of specific defence or an organ or system which could be cellular or humoral. You can often predict the infection if you know the underlying disease and will generally be low pathogenicity or opportunistic infections
how can you get a immunodeficiency?
congenitally or acquired
what is the innate defence?
it is non specific - everyone has the same
what is the adaptive immune system?
it is specific - everyone has different depending on what they are exposed and adapted to - humoral or cellular
what are the innate defences?
proteins, lungs, skin, commensal flora in gut, mucous membranes
what comprises the proteins in innate immunity?
interferons, acute phase proteins, lysozymes and complement
what is an example of a disruption to the lungs and what does it comprise?
in the lungs there are goblet cells and the muco-ciliary escalator. This is involved in CF
what is in the skin?
flora, sebum and acts as a barrier - burns can disrupt
what alters the normal commensal gut flora?
antibiotic treatment - immunosupressed - candida and C difficile as opportunistic infections
what comprises mucus membranes?
tears, phagocytes and urine
when are you more likely to pick up an infection?
extremes of age, pregnancy and malnutrition
what are the presenting characteristics or oral thrush?
white plaques and candidiasis
how do burns affect the immune system?
extensive burns make hosts more susceptible to organisms such as staph aureus, psuedomonas and strep
what is the neutrophil important for?
the initial breach of the innate defences
how can you classify neutrophil deficiency?
quantitatively - less are present - neutropenic
qualitatively - lose ability to kill or chemotaxis
what is involved in qualitative loss of neutrophils?
rare and congenital - lose ability to signal - chemotaxis
the killing power is inherited such as in CGD - risk of staph aureus infection
what is involved in the quantitative neutrophil deficiency?
it may be from cancer treatment, bone marrow malignancy or aplastic anaemia. It is especially important if there are fewer than 0.5x10^9 for prolonged time, 50% will develop infection with high mortality and over 50% of those with pseudomonal infections will die within 24 hours if not treated. It can be weeks long with bacterial or fungal risk
what is the risk of a neutropenic patient?
viral infection, bacterial infection - if having chemotherapy then can cause ulcers or bacteriaemia so normal flora can enter and cause infection and fungal infections such as candida in the blood stream which is rare and causes illness. Aspergillus goes into the alveoli via inhalation of hyphal spore - if have cancer as well it is exacerbated
how would you treat neutropenia?
use the empirical therapy concept and a broad spectrum treatment. Antipseudomonal penicillin (+gentamicin) and then if doesnt work add second line therapy on such as carbapenem. Granulocyte stimulating factors are less common and are used to correct immunodeficiency
how can T cell deficiencies be caused?
they can be acquired through drugs such as steroids or ciclosporin after transplantation or congenital which is rare and results in T cell dysfunction (+hypogammaglobulinaemia)