Micro Flashcards
what differentiates strep pyogenes from agalactiae?
- both β haemolytic
- only agalactiae grows on mac
- pyogenes is bacitracin sensitive
what differentiates strep viridans from pneumoniae?
- both are α haemolytic and neither grow on mac
- strep pneumoniae optochin sensitive
what is the anti-streptolysin O test?
- patients serum, some RBCs and streptolysin are used
- if pt has the antibodies, the red cells will not lyse because streptolysin will be neutralised, this is seen as a ‘button’ of cells
what HLA types are associated with coeliac disease?
HLA DQ2 (90%) and DQ8
what are the characteristics seen on small bowel biopsy of someone with coeliac disease?
- crypt hyperplasia
- villous atrophy
- intraepithelial lymphocyte infiltration
T/F genetic testing for HLA types in coeliac disease has good negative predictive value
True, can be pretty sure they don’t have the disease if they don’t have HLA DQ2 or DQ8
what type of cancer does coeliac disease predispose to?
EATL - enteropathy-associated T cell lymphoma
what does tissue transglutaminase do?
it deaminidates glutamine to glutamate on the gliadin peptide so that the peptide can now fit snuggly in the binding pocket of MHCII of (HLA DQ2 and 8)
what do the Coombs tests detect?
auto antibodies to RBCs
What does ANA stand for? what are its sens and spec?
Anti-nuclear antibody. 90-100% sensitive, 60% specific
Will someone with SLE flare up have low or high complement?
low, as it is being used up in many ways especially in the classical complement activation pathway
how does UV exposure precipitate SLE?
tissue damage -> necrosis -> DAMPs exposed to immune system
What is Reiter’s syndrome?
- reactive arthritis, urethritis and conjunctivitis
- occurs 2-4 weeks post GIT, or genital tract infection
- autoimmune disease
Organisms that can cause reactive arthritis?
Yersinia Salmonella Campylobacter Shigella Chlamydia Neisseria
What HLA is reactive arthritis associated with?
- HLA B27
