CP14 - Infection in the Immunocompromised Host Flashcards
examples of innate defences in the body
- skin
- interferons, lysozymes, complement, acute phase proteins
- mucous membranes
- commensal flora in the gut
how does the skin protect the body?
forms a physical barrier
has normal flora
secretes sebum
how do mucous membranes protect the body?
tears
bring flow
phagocytes
cilia
what physiological states make you more susceptible to poor immunity?
extremes of age
pregnancy
(malnutrition)
how is immunodeficiency classified?
congenital - primary
acquired - secondary
what forms the second line of defence in the body?
neutrophils. fewer neutrophils indicates increasing infection
what kind of defects can be observed in neutrophils?
qualitative - lose the ability to kill and chemotaxis
quantitive - either less in numbers or deficient in NADPH oxidase
what are the causes of qualitative defects in neutrophils?
(rare) congenital inadequate signalling abnormalities in receptors abnormalities in neutrophil movement
what is the cause of fewer neutrophils?
CGD
what causes neutrophils to have a deficiency in NADPH oxidase?
cancer treatment
bonne marrow malignancy
aplastic anaemia caused by drugs
what are patients with NADPH oxidase deficiency at risk of developing?
staph aureus infections
what is the medical term for low neutrophils?
neutropenia
when is neutropenia significant?
- less than 0.5 x 10^9 cells/L
OR - prolonged periods of neutropenia
what are the possible infections neutropenic patients could develop?
bacteria, fungal, maybe viral
which bacterial species can especially cause infections in neutropenic patients?
E coli
staph aureus
how can bacterial infections in neutropenic patients be treated?
amino glycoside and antipsuedomonal penicillin
2nd line antibiotics if needed
always give best guess ones before lab results come through
which fungi commonly cause infections in neutropenic patients?
candida, aspergillus
how can these fungal infections be treated?
antifungals
which pathogen is important to keep in mind in neutropenic patients?
pseudomonas. ensure antibiotics cover this species
which other form of medication is important to give neutropenic patients?
granulocyte stimulating factors - GCSF
drugs which stimulate the immune system
what are the 2 classes of t cells deficiency?
congenital
acquired - either via drugs or viruses
what is the consequence of t cell deficiencies?
opportunistic infections
how are viral infections in t cell deficient patients managed?
provide pre-emptive treatment for CMV
serology, prophylaxis and treatment with aciclovir and ganciclovir
how is cryptosporidiosis treated in a t cell deficient patient?
symptomatic treatment only
how can toxoplasma gondii present?
brain lesions/neurological signs
what symptoms does strongyloides sercoralis cause in immunodeficient patients?
multiplication of the parasite and tissue invasion. suspect in patients from tropical countries
what is a hypogammaglobinaemia?
problem with the antibodies
what are the classes of hypogammaglobulinaemias?
I1. congenital
2. acquired - multiple myeloma, burns, chronic lymphocytic leukaemia
what bacterial infections can be observed in patients with hypogammaglobulinaemia?
s. pneumoniae in respiratory tract
G. lambia or cryptosporidium in GI
how are infected patients with hypogammaglobulinaemias treated?
immunoglobulins, give them a blood product
what is the cause of complement deficiency?
genetic
rare
what kind of bacteria infect patients with complement deficiency?
encapsulated bacteria, neisseria meningitidis,
frequent but serious S. pneumoniae infections
what are the functions of the spleen?
produces substances involved in the complement
B cells
removal of opsonised bacteria from the blood
controls amount of rbcs in blood
what are the causes of splenectomy?
traumatic
surgical
functional - eg. sickle cell anaemia
which microbes need to be looked out for in splenectomies?
S. pneumoniae H influenzae type B N. meningitides Malaria consequences - high mortality
how can opportunistic infections in patients without spleens be prevented?
vaccination
prophylactic penicillin
education - seek help if unwell
what are biologics?
antibodies or other peptides that inhibit inflammatory cytokine signals
when are biologics used?
treatment of diseases - RA TB herpes zoster L. pneumophila Listeria monocytogenes
what is one dangerous side effect of organ transplantation?
immunosuppression due to anti-rejection treatment
degree of immunosuppression depends on how closely the donor and recipient are matched
how can infections after organ transplantation be managed?
treat the known infection
remove catheters/cannula if they are the site of infection
reverse defect if possible or stop immunosuppression
how can infections in the immunocompromised be prevented?
hand washing/aseptic/protective isolation
vaccines - avoid live vaccines in t ell deficient patients
prophylactic antimicrobials
passive immunoglobulin
special diet
