What
swabs can be used with TestPack Strep A?
Any polyester (Dacron-tipped) swabs can be used (like the ones
supplied in the test). It is not possible to use calcium
alginate or rayon swabs.
Can saliva or
sputum specimens be used with TestPack Strep A test?
No. The test has only been validated for throat swab specimens.
If
I want to perform bacterial culture in addition to the TestPack
Strep A test do I need to take two swabs from the
patient?
Two swabs may be taken but it is possible to use the same throat
swab to perform both tests. Inoculate the blood agar plate
first and then perform the TestPack Strep A
test. It is not possible to perform bacterial culture after the
TestPack Strep A test because the organisms
will have been killed during the extraction procedure.
Can the
kit be used directly from the fridge?
No.
although the kit can be stored at 2 - 30°C, it must be allowed to
equilibrate at 18 - 30°C for a minimum of 30 minutes before
use.
The extraction procedure did not
show the correct pink to yellow to pink colour change. What does
this mean?
The reagents may have been added in the wrong order. It is
essential that the correct extraction procedure is followed
otherwise the Strep A antigen will not be extracted from the swab.
If the extract remains yellow after 3 drops of Reagent 3 have been
added it is possible to add an additional drop of Reagent 3.
What is
the purpose of the Positive On Board Control?
The Positive On Board Control demonstrates the functionality of the
antibodies that detect Group A Streptococcal antigen. It will
always be produced in a valid test whether or not Strep A antigen
is present in the sample extract.
The Patient Bar
(vertical line) has appeared but it is fainter than the Minus Bar
(horizontal line). How should this result be
interpreted?
The presence of a Patient Bar is indicative of a positive result
providing that the test was read at the correct time. The strength
of the patient bar depends on the amount of Streptococcus
group A antigen in the sample extract; hence low-level antigen
would result in a weak patient bar.
A patient was recently treated
with antibiotics but still shows a positive result with TestPack
Strep A. Bacterial culture was negative.
TestPack Strep A is an antigen detection test
for Streptococcus group A so will detect both viable and
non-viable organisms. The positive result is due to
non-viable Streptococcus group A organisms which have not
yet cleared from the body. The same is true for any other rapid
Strep A test.
How specific
is the TestPack Strep A test?
As part of the specificity testing organisms present in the
respiratory tract (either as pathogens or normal flora) were tested
and no cross reactivity was observed. During clinical trials
TestPack Strep A test was shown to be 98.4%
specific against bacterial culture.