PREFINAL LABORATORY L3: ASO LATEX AGGLUTINATION

Question 1

ASO kit is storage temperature

Answer 1

2-8C

Question 2

principle of ASO test

Answer 2

latex particles coated with streptolysin O are agglutinated when mixed with samples containing ASO

Question 3

describe ASO latex test

Answer 3

slide agglutination test for the qualitative and semi-quantitative detection of anti-streptolysin O

Question 4

what kind of enzyme is streptolysin O

Answer 4

toxic immunogenic exoenzyme

Question 5

what organisms produce streptolysin O

Answer 5

beta-hemolytic streptococci groups A, C, and G

Question 6

disease associations of streptolysin O

Answer 6

rheumatoid fever
acute glomerulonephritis
streptococcal infections

Question 7

describe rheumatic fever

Answer 7

inflammatory dse affecting connective tissue from several parts of human body

Question 8

example of body parts affected by rheumatoid fever

Answer 8

skin, heart, joints

Question 9

describe acute glomerulonephritis

Answer 9

renal infection that affects mainly renal glomerulus

Question 10

reagents of ASO test kit

Answer 10

ASO latex antigen
positive control
negative control

Question 11

components of ASO latex antigen

Answer 11

latex particles coated with streptolysin O, pH 8.2 preservative

Question 12

components from human origin have been tested and found to be negative of what antigens/antibody

Answer 12

HBsAg, HCV, and antibody to HIV 1/2

Question 13

ASO latex sensitivity is calibrated against what standard

Answer 13

ASO International Standard from NIBSC 97/662

Question 14

T or F:

ASO test kits can be frozen

Answer 14

F
could change the functionality of test

Question 15

vials must be kept at what position

Answer 15

vertical position

Question 16

what should be done if vials are changed in position

Answer 16

gently mix to dissolve aggregates that may be present

Question 17

what indicates the reagent deterioration

Answer 17

presence of particles and turbidity

Question 18

additional equipment required in ASO test

Answer 18

mechanical rotator (80-100 rpm)
vortex mixer
50 ul pipette

Question 19

sample used in ASO test

Answer 19

fresh serum

Question 20

fresh serum is stable for how many days and at what temperature

Answer 20

7 days at 2-8C or 3 months at -20C

Question 21

what should be done to samples with fribrin

Answer 21

centrifuged

Question 22

specimens to be avoided

Answer 22

hemolyzed or lipemic

Question 23

procedure for qualitative method

Answer 23

1) Allow the reagents and samples to reach room temperature.
2) Place 50 uL of the sample and one drop of each Positive and Negative controls into separate circles on the slide test.
3) Mix the ASO-latex reagent vigorously or on a vortex mixer before using and add one drop (50 uL) next to the sample to be tested
4) Mix the drops with a stirrer, spreading them over the entire surface of the circle. Use different stirrers for each sample.
5) Place the slide on a mechanical rotator at 80-100 rpm for 2 minutes.

Question 24

what kind of results will show if read after 2 minutes

Answer 24

false positive

Question 25

what can be reduced if samples and reagents are used at low temperatures

Answer 25

sensitivity of the test

Question 26

first step of semi-quantitative method

Answer 26

make serial two-fold dilutions of sample in 9 g/L saline solution

Question 27

the presence of agglutination indicates

Answer 27

ASO concentration equal or greater than 200 IU/mL

Question 28

this is defined as the highest dilution showing a positive result in semi-quantitative method

Answer 28

titer

Question 29

formula of approx ASO concentration

Answer 29

200 x ASO titer = IU/mL

Question 30

reference values of ASO

Answer 30

up to 200 iU/mL (adults) 100 iU/mL (children <5 years old)

Question 31

analytical sensitivity of ASO test

Answer 31

200 (+/- 50) IU/mL

Question 32

prozone effect in ASO test

Answer 32

no prozone effect was detected up to 1500 IU/mL

Question 33

diagnostic sensitivity of ASO test

Answer 33

98%

Question 34

diagnostic specificity of ASO test

Answer 34

97%

Question 35

substances that do not interfere with ASO test

Answer 35

bilirubin (20 mg/dL) hgb (10 g/L) lipids (10 g/L) rheumatoid factors (300 IU/mL)

Question 36

what can cause false negative results

Answer 36

early infx children from 6 mos to 2 years

Question 36

conditions that can cause false positive result

Answer 36

rheumatoid arthritis scarlet fever tonsilitis several streptococcal infx healthy carriers

Question 37

titration at biweekly intervals during how many weeks are advisable for dse evaluation

Answer 37

4 or 6 weeks