Flashcards in Practical Deck (32):
Antistreptolysin O titration
A test in which patient serum is added to RBCs and streptolysin; in patients with a strep. pyogenes infection, there are anti-streptolysin antibodies present which inhibit RBC lysis.
The ELEK plate
Tests for C. diptheriae toxins. Vertical paper has antiserum; precipitate indicates positive result.
A method of staining of Corynebacterium diptheriae to show polyphosphate granules.
Hot malachite green
used to stain for spores
Caused by C perfringens
Important in wound infection, after appendicitis, septicaemia after injury. Sensitive to metronidazole.
Quantify Ab or Ag
Reverse passive haemagglutination
Chemically bind RBCs with antibody; titre with sample; if it agglutinates, then antigen present. Used to check for microbial antigens.
Anti-HCG Ab binds HCG coated latex beads unless it has been previously bound by HCG in the urine. A positive test is where there is no precipitate, because hCG from the urine not the beads binds the antibodies.
Gel precipitation - several separate lines present
More than one antigen, more than one Ab
Plaque forming cells
Detects lymphocytes secreting Ab; if the person has been exposed to the antigen before, there will be areas of lysis in surround as will produce Ab leading to complement lysis
Complement fixation test - minimal haemolytic dose.
Titrates haemolytic activity of complement; the highest dilution that gives 100% lysis is 1 minimal haemolytic dose.
Complement fixation test
Determine how much Ab will form enough complexes to inactivate all complement. Use titred complement. Controls = complement + sera, complement + test antigen. Positive test is no lysis.
Use latex beads bound to anti-sera against the surface glycoprotein O or H antigens; clumping is a positive result
Positive for Cl. perfringens.
Agglutination = positive result
Thrombus with laminations
Venous thrombus without laminations
Troponin 1 and MB creatine kinase
Usually only found in cardiac myocytes.
Px = (M to the x times e to the -m)/x!
Where m = the moi and x = number of time for target to be hit. moi = phage per cell
In immunoelectrophoresis, what moves to the positive pole?
In immunoelectrophoresis, what moves to the negative pole?
In immunoelectrophoresis, what moves to the positive pole, but is generally central?
the Coombs test used for...
Used to test for haemolytic disease of the newborn.
the Coombs test technique
Anti-RhD is bound to RBCs. Other Abs are in serum. Wash cells to get rid of other Abs, then add Anti-human Ab; this binds Fc or Anti-RhD Ab, causing INDIRECT AGGLUTINATION.
Influenza haemagglutination assay
Influenza virus directly agglutinates fowl RBC
Virus neutralisation assay
Finds highest dilution of serum which will neutralise the virus (by Ab binding); demonstrates infection.
Very tiny colonies, chains of gram +ive cocci. Use catalase test to differentiate from staph epidermidis. Also lactose fermenting (MAC red, CLED yellow)
Strep pyogenes; further tests
Always mention Lancefield grouping for cell wall polysaccharide; should be Lancefield group A
chains of gram +ive cocci; volcano shaped colonies. Incomplete haemolysis.
Normal mouth flora.