Laboratory Diagnosis

Question 1

What are the 4 common classification schemes for streptococcus?

Answer 1

• hemolytic patter in SBA
• physiologic characteristics
• serologic grouping/typing pf C carbohydrate (lancefield classification)
• biochemical characteristics

Question 2

Four groups of physiologic characteristics of strep.

Answer 2

• Pyogenic streptococci
• Lactococci
• Enterococci
• vridans streptococci

Question 3

How to extract the C carbohydrates from streptococci?

Answer 3

By placing the organisms in dilute acid and heat for 10 mins.

Question 4

It has been used as an inexpensive test for presumptive identification of S. pyogenes.

Answer 4

Bacitracin Susceptibility

Question 5

What strep is (S) and (R) to bacitracin?

Answer 5

(S)- S. pyogenes
(R)- S. agalactiae

Question 6

This biochem. Test is used for identification of S. galactiae.

Answer 6

CAMP Test

Question 7

3 ways to perform CAMP Test.

Answer 7

• use of B-lysin producing strain of S. aureus
• used of disk impregnated with the B-lysin.
• rapid CAMP test (placing a drop of B- lysin on area of confluent growth of bacteria.

Question 8

This biochem test is useful test for differentiating S. agalactiae from other B-hemolytic strep.

Answer 8

Hippurate Hydrolysis

Question 9

This enzyme of S. agalactiae hydrolyze sodium hippurate.

Answer 9

Hippuricase

Question 10

In hippurate test, when sodium hippurate is hydrolyzed by the enzyme of S. agalactiae into ___.

Answer 10

• Sodium benzoate
• Glycine

Question 11

This test provides a highly probability for the presumptive identification of B- hemolytic GAS and Nonhemolytic group D.

Answer 11

Pyrrolidonyl-a-naphthylamide Hydrolysis test

Question 12

It is the only streptococcus that is positve in PYR test.

Answer 12

Strep. pyogenes

Question 13

What is being detected in PYR test?

Answer 13

The activity of L- Pyrrolidonyl arylamidase (pyrrolidonyl aminopeptidase)

Question 14

What organisms are positive in PYR?

Answer 14

• S. pyogenes
• Enterococcus

Question 15

It is a peptidase that hydrolyzes peptide bonds adjacent to a free amino group.

Answer 15

Leucin Aminopeptidase

Question 16

The substrate leucine-B-naphthylamide is hydrolyzed to___.

Answer 16

B-naphthylamine

Question 17

What reagent is added in LAP test to ptoduce red color that signifies (+) results?

Answer 17

Paradimethylaminocinnamaldehyde reagent (PDMACA)

Question 18

What organisms are LAP (+)?

Answer 18

Streptococcus, Enterococcus, Pediococcus.

Question 19

What organisms are (-) in LAP test?

Answer 19

Aerococcus
Leuconostoc

Question 20

This test is used to differentiate the small colony from large colony containing the Group C and G antigen.

Answer 20

Voge-proskauer test

Question 21

What is being detecred in VP test?

Answer 21

ACETOIN production from glucose

Question 22

In VP test, what is the temp of incubation and time requirement.

Answer 22

35°C for 6 hours

Question 23

In VP test, after the incubation period, what should be added?

Answer 23

• 5% a-napthol
• 40% KOH

Question 24

Positive color in VP test.

Answer 24

Red or Pink

Question 25

What is positive and negative in VP test?

Answer 25

(+) small colonies- S. anginosus (-) large colonies

Question 26

This test detects the rxn. Of B-D-glucoronidase

Answer 26

B-D-Glucoronidase test

Question 27

What is positive and negative in B-D-Glucoronidase test?

Answer 27

(+) large colonies (-) small colonies

Question 28

Test for identification schemes for nonhemolytic, catalase-negative, gram (+) cocci

Answer 28

Bile esculin and salt tolerance test

Question 29

Two steps in bile esculin test.

Answer 29

1. detect the growth of bacteria in 40% bile 2. The ability to hydrolyze esculin

Question 30

What are positive in bile esculin test?

Answer 30

D. streptococci and Enterococci

Question 31

In salt tolerance test what is the concentration of the salt?

Answer 31

6.5% NaCl

Question 32

Positive and negative in salt tolerance test.

Answer 32

(+) Enterococcus (-) group D strep.

Question 33

It is a test that adds ethylhydrocuprein hydrochloride to the surface of SBA with a-hemolytic strep.

Answer 33

Optochin susceptibility test

Question 34

(R) and (S) in optochin test.

Answer 34

(R)- S. viridans group (S)- S. pneumoniae

Question 35

Zone of inhibition requires to be considered as susceptible in optochin test.(measurement)

Answer 35

>14 mm with 6mm disk or >16 mm with 10mm disk

Question 36

This test correlates with optochin susceptibility test.

Answer 36

Bile solubility

Question 37

In bile solubility test, __ took the advantage Becuase of the enzyme amidase.

Answer 37

S. pneumoniae

Question 38

In bile solubility test, S. pneumoniae in solution of ____ lyses and make the broth clear.

Answer 38

Sodium deoxycholate

Question 39

Organisms positie and negative in bile solubility test.

Answer 39

(+) S. Pneumoniae (clear) (-) Viridans group (turbid)

Question 40

This test can be accomplished by the detection of group-specific antigen from isolates colonies.

Answer 40

Immunoassays

Question 41

T or F Immunoassays are a speedy test, and it is also expensive.

Answer 41

True