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BRS/POM MOCKS > POM MOCK 1- diagnostic bacteriology, histo, cancer, vaccines,transfusion > Flashcards

POM MOCK 1- diagnostic bacteriology, histo, cancer, vaccines,transfusion Flashcards

1
Q

What colour do gram negative bacteria stain?

A

Pink.

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2
Q

What colour do gram positive bacteria stain?

A

Purple.

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3
Q

How is a gram stain performed?

A

Bacteria culture spread on glass slide. Heat to fix bacteria to surface. Application of crystal violet solution to slide. Application of iodine to slide. Alcohol wash performed on slide. Counter stain performed by application of safranin.

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4
Q

What occurs to gram positive and gram negative bacteria after alcohol wash?

A

Gram positive bacteria stay purple as iodine and crysal violet can’t be washed out of cell wall. Gram negative bacteria lose purple colour.

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5
Q

What shape are coccus bacteria?

A

Spheres.

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6
Q

What shapes are bacillus bacteria?

A

Round ended cylinders.

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7
Q

What is the hemolysis test useful for differentiating?

A

Differentiating members of the genera Staphylococcus, Streptococcus and Enterococcus.

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8
Q

What would you see in alpha hemolysis?

A

Opaque green zone.

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9
Q

What would you see in beta hemolysis?

A

Transparent zone.

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10
Q

What would you see in gamma hemolysis?

A

No zone.

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11
Q

What is the lactose fermentation test useful for differentiating?

A

Useful for differentiating gram negative bacteria.

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12
Q

What type of agar is used in lactose fermentation test?

A

MacConkey agar.

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13
Q

Colour change in lactose fermentation test if bacteria is lactose fermenting? Why?

A

Red to pink. If the bacteria ferment lactose, then acid is produced as a by-product which decreases the pH of the media. Neutral red changes to pink when pH becomes acidic.

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14
Q

Colour change in lactose fermentation test if bacteria is lactose non-fermenting? Why?

A

Red to yellow. If the bacteria are lactose non-fermenters then they use the peptone instead, then ammonia is formed as a by-product which increases the pH of the media. Neutral red turns yellow when pH becomes basic.

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15
Q

What genus of bacteria produce catalase?

A

Staphylococci.

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16
Q

What genus of bacteria don’t produce catalase?

A

Streptococci.

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17
Q

What is the coagulase test useful for differentiating?

A

Members of the staphylococci genus.

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18
Q

What does coagulase do?

A

Enzyme produced that converts prothrombin to thrombin. Thrombin cleaves fibrinogen into fibrin. Factor VIIIa crosslinks fibrin to form fibrin clots.

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19
Q

How to perform coagulase test?

A

Application of bacteria to glass slide. Application of plasma to slide. Incubate for 15 seconds and gently rotate. Observe for clumps.

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20
Q

How is a biopsy prepared?

A

Tissue sample is preserved in formalin with cross linking proteins (tissue fixation). It is then embedded in paraffin wax. Cut by microtome. Sample mounted on microscope slide and analysed.

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21
Q

What specimen is used to look at stage of disease?

A

Resection specimens.

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22
Q

Advantage of frozen section?

A

Provides quick diagnosis as examined in real time during operation.

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23
Q

Disadvantage of fine needle aspirate?

A

No information on tissue architecture.

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24
Q

What are antibody conjugates?

A

Addition of molecules to Fc region of antibody.

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25
Q

What antibody conjugate is used for rapid measurement of levels of molecules in a sample?

A

Fluorescent probe

26
Q

Use of drug antibody conjugate?

A

Anticancer antibody with cytotoxic drug.

27
Q

How is ELISA prepared?

A

Clinical sample mixed with complementary antibody that has conjugated enzyme. Wash away unbound antibody. Enzyme makes coloured product from added colourless substrate. Measure absorbance and refer to standard curve.

28
Q

What is flow cytometry used for?

A

Identity of cell surface molecules, size and granularity of cells.

29
Q

How is flow cytometry done?

A

Cells labelled with differently conjugated antibodies. Run a stream of single cells through a laser beam. Colour of light emitted and the forward or side scatter of the laser beam analysed.

30
Q

What is neoplasm?

A

Autonomous growth of tissue that has escaped normal constraints of cell proliferation.

31
Q

What is a hamartoma?

A

Benign overgrowth. Disorganised mass and is slow growing.

32
Q

What is a heterotopia?

A

Normal tissue in the wrong place.

33
Q

What is a teratoma?

A

Tumours derived from germ cells. Can contain tissue from 3 germ cell layers and can contain cancers.

34
Q

What does cancer grade refer to?

A

Tissue architecture. How much does it look like compared to the normal physiological state.

35
Q

What may you see if you look at cancer cells?

A

High nucleo-cytoplasmic ratio. Abnormal mitosis (tripolar - 3 daughter cells).

36
Q

How do cancer cells spread by direct extension?

A

Desmoplastic response - fibroblast proliferation. Angiogenesis.

37
Q

How are Recombinant protein vaccines produced?

A

Surface antigen gene is isolated. Gene is inserted to the yeast cell DNA. Yeast produces antigen. Antigen is purified and use in vaccine.

38
Q

Disadvantages of recombinant protein vaccines?

A

Relatively expensive and not very immunogenic.

39
Q

What challenge is present when making vaccines for bacteria? What type of vaccine overcomes this challenge?

A

Bacterial often have a capsule which is made of a polysaccharide. This is not very good at inducing a B cell response since it is a thymus independent antigen. Conjugate vaccines.

40
Q

How do conjugate vaccines work?

A

Polysaccharide coat is coupled to an immunogenic carrier protein. Protein enlists CD4 cells to boost B cell response to polysaccharide.

41
Q

Advantages of conjugate vaccines?

A

Highly effective at controlling bacterial infection.

42
Q

Disadvantages of conjugate vaccines?

A

Cost, carrier protein interference, very strain specific.

43
Q

Advantages of dead pathogen vaccines?

A

Immunogenic as you leave antigenic components intact and in context of other antigen. Cheap. Quick.

44
Q

Disadvantages of dead pathogen vaccines?

A

Pathogen needs to be grown, antigenic drift can occur when grown and chemicals can also alter the antigen(not same pathogen that is present in population).

45
Q

How do live attenuated vaccines work?

A

Pathogen continually grown and mutated until it loses its virulence. Can be given to individual and can replicate.

46
Q

Advantages of live attenuated vaccines?

A

Can trigger a strong immune response and provides immunity in local site of infection.

47
Q

What do adjuvants do and how do they work?

A

Present in vaccines and give a more robust immune response. They do this by inducing danger signals that activate dendritic cells and these can present antigen to T cells. Upregulates stimulatory cytokines.

48
Q

What determines the clinical importance of a blood group?

A

Capacity of antibodies against the specific RBC antigens to cause haemolysis of RBC.

49
Q

What medical complications can and cannot occur due to ABO antibodies?

A

Acute HTRs through activation of the complement system resulting in massive intravascular haemolysis. However, they cannot cross the placenta to cause HDFN.

50
Q

Why does haemolytic disease of the fetus and newborn (HDFN) happen?

A

Fetus has a different RBC antigen from mother. Antibody that corresponds to this antigen travels across placenta.

51
Q

How can a RhD negative individual develop antibodies for RhD?

A

Transfusion of incompatible blood or if fetal RhD positive RBC’s enter maternal bloodstream.

52
Q

Transfusion of incompatible RhD blood can lead to?

A

Delayed HTR - Extravascular haemolysis. Can result in high levels of bilirubin, jaundice or anaemia.

53
Q

When transfusing platelets what is important?

A

Expression of ABO antigens on platelets is relatively low. Make sure it is high titre negative (doesn’t have high levels of anti A or anti B).

54
Q

When transfusing FFP or cryoprecipitate what needs to be checked?

A

Antibodies. High titre negative or AB plasma (universal donor).

55
Q

If you know a mother is RhD negative and has a fetus which is RhD positive what can be given to the mother?

A

Mother can be given anti d immunoglobulin to prevent alloimmunisation of RhD antibodies in her system which could lead to HDFN. Anti d immunoglobulin destroys any positive RhD fetal red blood cells that have entered maternal bloodstream.

56
Q

What is the emergency blood type?

A

Group O RhD negative blood.

57
Q

When transfusing platelets what can be given along with it?

A

Anti-D immunoglobulin. Platelets can contain RhD red cells fragments.

58
Q

How is an antibody screen test done?

A

Patient serum added to panels that contain red blood cells that have known antigens. Anti human globulin is added to visualise agglutination.

59
Q

What is a cross match?

A

Patient serum mixed with sample of red blood cells chosen for transfusion.

60
Q

What infection screening tests are done for blood?

A

HIV, Hepatitis (B,C,E), HLTV and syphillis.

61
Q

What is FFP used to treat?

A

Bleeding, multiple clotting factor deficiencies.

62
Q

When is cryoprecipitate used?

A

To treat haemophilia A or VWF disease.

BRS/POM MOCKS (23 decks)

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