Laboratory Diagnosis Flashcards
What are the 4 common classification schemes for streptococcus?
- hemolytic patter in SBA
- physiologic characteristics
- serologic grouping/typing pf C carbohydrate (lancefield classification)
- biochemical characteristics
Four groups of physiologic characteristics of strep.
- Pyogenic streptococci
- Lactococci
- Enterococci
- vridans streptococci
How to extract the C carbohydrates from streptococci?
By placing the organisms in dilute acid and heat for 10 mins.
It has been used as an inexpensive test for presumptive identification of S. pyogenes.
Bacitracin Susceptibility
What strep is (S) and (R) to bacitracin?
(S)- S. pyogenes
(R)- S. agalactiae
This biochem. Test is used for identification of S. galactiae.
CAMP Test
3 ways to perform CAMP Test.
- 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.
This biochem test is useful test for differentiating S. agalactiae from other B-hemolytic strep.
Hippurate Hydrolysis
This enzyme of S. agalactiae hydrolyze sodium hippurate.
Hippuricase
In hippurate test, when sodium hippurate is hydrolyzed by the enzyme of S. agalactiae into ___.
- Sodium benzoate
- Glycine
This test provides a highly probability for the presumptive identification of B- hemolytic GAS and Nonhemolytic group D.
Pyrrolidonyl-a-naphthylamide Hydrolysis test
It is the only streptococcus that is positve in PYR test.
Strep. pyogenes
What is being detected in PYR test?
The activity of L- Pyrrolidonyl arylamidase (pyrrolidonyl aminopeptidase)
What organisms are positive in PYR?
- S. pyogenes
- Enterococcus
It is a peptidase that hydrolyzes peptide bonds adjacent to a free amino group.
Leucin Aminopeptidase
The substrate leucine-B-naphthylamide is hydrolyzed to___.
B-naphthylamine
What reagent is added in LAP test to ptoduce red color that signifies (+) results?
Paradimethylaminocinnamaldehyde reagent (PDMACA)
What organisms are LAP (+)?
Streptococcus, Enterococcus, Pediococcus.
What organisms are (-) in LAP test?
Aerococcus
Leuconostoc
This test is used to differentiate the small colony from large colony containing the Group C and G antigen.
Voge-proskauer test
What is being detecred in VP test?
ACETOIN production from glucose
In VP test, what is the temp of incubation and time requirement.
35°C for 6 hours
In VP test, after the incubation period, what should be added?
- 5% a-napthol
- 40% KOH
Positive color in VP test.
Red or Pink
What is positive and negative in VP test?
(+) small colonies- S. anginosus
(-) large colonies
This test detects the rxn. Of B-D-glucoronidase
B-D-Glucoronidase test
What is positive and negative in B-D-Glucoronidase test?
(+) large colonies
(-) small colonies
Test for identification schemes for nonhemolytic, catalase-negative, gram (+) cocci
Bile esculin and salt tolerance test
Two steps in bile esculin test.
- detect the growth of bacteria in 40% bile
- The ability to hydrolyze esculin
What are positive in bile esculin test?
D. streptococci and Enterococci
In salt tolerance test what is the concentration of the salt?
6.5% NaCl
Positive and negative in salt tolerance test.
(+) Enterococcus
(-) group D strep.
It is a test that adds ethylhydrocuprein hydrochloride to the surface of SBA with a-hemolytic strep.
Optochin susceptibility test
(R) and (S) in optochin test.
(R)- S. viridans group
(S)- S. pneumoniae
Zone of inhibition requires to be considered as susceptible in optochin test.(measurement)
> 14 mm with 6mm disk or
16 mm with 10mm disk
This test correlates with optochin susceptibility test.
Bile solubility
In bile solubility test, __ took the advantage Becuase of the enzyme amidase.
S. pneumoniae
In bile solubility test, S. pneumoniae in solution of ____ lyses and make the broth clear.
Sodium deoxycholate
Organisms positie and negative in bile solubility test.
(+) S. Pneumoniae (clear)
(-) Viridans group (turbid)
This test can be accomplished by the detection of group-specific antigen from isolates colonies.
Immunoassays
T or F
Immunoassays are a speedy test, and it is also expensive.
True
