3- pulmonary infection in immunocompromised Flashcards
who are risk for developing chronic pulmonary infections?
people with abnormal host response (immunodeficiency or immunosuppression) and people with abnormal innate host defence due to damaged bronchial mucosa, abnormal cilia, abnormal secretions, repeated insult, aspiration, indwelling material like bits of plastic + metal inside you
what are some causes of immunosuppression?
- Drugs
- Malignancy = myeloma, lymphoma, leukaemia - need to look out for (in that order)
are chronic lung infections normal?
no, that’s why if chronic lung infection then should be investigation into what underlying cause
- people with severe acute infection should also be investigated
what is the pnemonic to think if immunocompromised?
SPUR
s= significant
p = persistent
u = unusual (either organism or site)
r = recurrent/resistant
what is primary immunodeficiency?
immunodeficiency arising from genetic mutations affecting development or function of immune system components
= like immunoglobulin deficiencies
what is secondary immunodeficiency?
Results from factors external to the immune system, such as diseases or medical treatments, which impair immune function
= like HIV and removal of spleen
what are some examples of primary immunodeficiency?
- IgA deficiency, common at varying levels - rarely chronic infections so not really massive problem
- hypogammaglobulinemia, low levels of all antibodies, much rarer and increased risk of acute + chronic infections
- common variable immunodeficiency (CVID) = most common, presents recurrent infections = low IgG and at least one of low IgA and IgM - also has problems of mature B cells due to not making antibodies
- Specific Polysaccharide Antibody Deficiency (SPAD), deficiencies in antibodies that target certain things like streptococcal infections
what are examples of secondary immunodeficiency?
- Hyposplenism – reduced function due to congenital or post splenectomy
- Immune paresis (immune system there in numbers but don’t work). conditions such as Myeloma, lymphoma, metastatic malignancy can cause immune paresis
- myeloma = make a lot of one type of IgG but don’t work, so loads of monoclonal
- lymphoma = cancer in lymph nodes so immune systems don’t work properly
- HIV – progressive depletion of CD4+ T cells →if not treated, classically present with opportunistic infections. AIDS (final stage HIV) much more rare now as people get treated, we’ll get lots more lectures in further years
what are some drugs that cause immunosuppression?
- steroids, very widely immunosuppressive, if get too much can be suppressed for a while
- methotrexate, common treatment for connective tissue disorders, very suppressive
- cyclophosphamide, for severe life threatening autoimmune, very suppressive - completely wipes out
- chemotherapy drugs
- monoclonal antibodies drugs
- leflunomide
what are some immunosuppressive monoclonal antibody drugs?
- Infliximab, etanercept: TNFa, can’t be given if TB as reactivate latent
- Rituximab: targets CD20 so suppresses B cells - so less antibodies being made, immunosuppression lasts for very long time
- Tocilizumab: targets IL-6, was used in covid, completely wipes out CRP (complement pathway) suppressed for 6-8 weeks, important
what types of things can damage bronchial mucosa leading to defective innate host defence?
- smoking
- recent pneumonia or viral infection
- malignancy
what types of things can cause abnormal cilia leading to defective innate host defence?
- kartagener’s syndrome (situs inversus - organs on wrong side)
- young’s syndrome
what types of things can cause abnormal secretions leading to defective innate host defence?
- cystic fibrosis
- channelopathies (less common, pretty rare)
what does repeated insult mean?
if get one infection, you get over it but if keep getting bacteria and infections thrown at you, much harder to get over
what can cause recurrent aspiration and what is it?
= poor swallow means oral secretions are swallowed down trachea and into lung rather than epiglottis closing properly and secretions into stomach
causes = NG feeding (put in wrong), poor swallow, pharyngeal pouch (fills with food & fluid and then slowly leaks out into wrong hole)
