ASO Flashcards
ASO
what’s the first thing you need to consider when doing ASO testing?
avoid hemolysis at all time since we are checking for hemolytic factors.
causes of hemoylsis: prolonged tourniquet application, difficulty in extraction of blood, excessive suction of aspiration
ASO
why time of collection should be noted for this test?
time of collection is very important due to its incubation period. so it should be noted, to avoid any false positive and negative results. for instance, collection of sample is done during the 1st week of infection, so there would be low values of antibodies reacting to the infection during that time since incubation period is 2 weeks.
do not solely rely on the kit results, esp. when the result is NEGA.
ASO
give 1 cause of false negative then solution or what will you do if you encounter these such things?
collection of samples earlier than the incubation period
it should be confirmed by an anti-DNAse test to determine the organisms’ ability to hydrolyze DNA and use it as a carbon and energy for its growth.
ASO
what specific antibodies that will appear in the patient serum days after the infection? what should be noted in order to identify properly and to avoid any false results.
IgG
always remember the time of infection
the incidence decreases, as the time increases.
ASO
you extracted a blood wherein the infection happened 6 months ago. what could be the result?
the result could be erroneous, because antibody levels begin to rise after 1-3 weeks of streptococcus infection, peaks in 3-5 weeks, and falls back to insignificant levles in 6 months.
values should be correlated with a clinical diagnosis.
ASO
what if the titer does not decrease?
that means that a recurrent or chronic infection may exist.
ASO
why the specimen for this test should be serum that is clear and hemolysis free?
because these certain organisms will react completely with hemolysis.
ASO
why reagent should be shaken properly before use?
in order to remove any particles and to avoid any false positive or negative reactions.
once shaken, it should be uniform without visible clumping.
ASO
why plasma should not be used in testing ASO?
because it contains a protein called fibrinogen in which can clump together (agglutinate) with the test particles even if there are no antibodies to streptococcal bacteria.
ASO
what if you mistakenly used a plasma in testing ASO? what could be the result?
it could lead to false positive since fibrinogen can agglutinate with the test particles. due to that, it seem like there’s an infection when there isn’t
ASO
what is the principle? explain.
AGGLUTINATION
ASO latex slide test is a rapid test used for screening which it can be used as a qualitative or a semi-quantiative measurement of antibodies to ASO.
ASO
differentiate the positive and negative control
positive control contains with a human serum while negative control contains animal serum. these controls both contain preservative and should be stored at 2-8C in a vertical position.
ASO
how will you interpret the result?
examine macrosopically for presence of agglutination immediately after rotating the cards for 2 mins. reaction read after 2 mins time may be invalid.
ASO
why false positive may be obtained in conditions such as scarlet fever, tonsillitis, several streptococcal infections and even in healthy carriers?
false positive can still occur in these situations ASO antibodies can remain elevated in the bloodstream for weeks or even months after a successful strep infection. This means a positive test result might not indicate a current problem. the body creates antibodies that react not only to strep bacteria but also to similar proteins found in other types of infections, like scarlet fever or tonsillitis. Some healthy individuals carry strep bacteria in their throats without showing any symptoms. These carriers may have slightly elevated ASO levels, though typically not high enough to be flagged as positive.
ASO
why false negative reactions may occur in early primary infections and children aged between 6 months and 2 years old?
Children between 6 months and 2 years have a developing immune system. Their response to a strep infection might be weaker, resulting in lower ASO production compared to older children or adults. This can lead to a false negative result, even if they are infected.
