serodiagnostic tests for streptococcal diseases Flashcards
the pathogenicity of streptococcus is attributed to the number of extracellular products it produces such as hemolytic toxin (__ & __), and enzymes, such as __ and __
streptolysin o and s, hyaluronidase, deoxyribonuclease B (DNase)
measures antibodies developed by a host’s immune system in response to the hemolytic toxin streptolysin o
ASO titer tert
t/f: aso titer test is a semi quantitative procedure in which different dilutions of a patient’s serum are prepared and mixed with a fixed amount of streptolysin o antigen
t
the (presence / absence) of hemolysis indicates the presence of the anti-streptolysin o antibody and therefore denotes a (positive/negative) result and the lack of ASO antibodies
absence, positive
reconstitute the streptolysin o reagent with distilled water. this should be used within __ minutes
within 20 minutes
centrifuge the tubes for __ min at __ rpm
1 minute, 1,500rpm
the (first/last) tube demonstrating no hemolysis represents the endpoint
last
the ASO titer is expressed in __
todd units, IU/mL
tube 11 represents the __
red cell control
tube 11 should exhibit __ after standing for __hours
no hemolysis, 2 hours
tube 12 is the __
streptolysin control
tube 12 should show __ for the patient test result to be valid
marked to complete hemolysis
titrations of specimens at __ intervals for __ weeks following streptococcal infection should be done to yireld more meaningful information
bi-weekly, 4-6 weeks
t/f: a single anti-streptolysin o titer of 125 does not provide much information
t
if the titer rises from a baseline of __ units, it is considered significant and suggests a current or recent streptococcal infection that may progress into a secondary or streptcoccal sequelae infection
50 units
a drop in the ASO titer from 250 units to 125 units is indicative of __
recovery
the normal range of antibody titer is __ units
0-125 units
a patient with rheumatic fever may demonstrate an average antibody titer of __
500 IU/mL
positive result of aso latex test indicates that the aso content in the patient’s serum is __
> 200 IU/mL +/- 15
rapid multi-enzyme test that cam simultaneously detect the antibodies of the different extracellular antigens of group a streptococcues
streptozyme test
among the streptococcal antibodies detected by this test are __, __, __, and __
anti-streptolysion o (ASO), anti-deoxyribonuclease b (ADN-B), anti-streptokinase (ASK), anti-hyaluronidase (AH)
laboratory test commonly used in diagnosing recent post-streptococcal sequelae infections
streptozyme test
a suspension of __ sensitized with group a streptococcus extracellular antigens will react with the corresponding antibodies in a patient’s serum
aldehyde-fixed sheep red cells
positive
