The Back Up Throat Culture Becomes Optional

The Back Up Throat Culture Becomes Optional

Summary
The back up throat culture has been done in our office for many years when the rapid strep is negative.   The accuracy of the rapid strep in our office combined with increased regulatory requirements to perform in office throat cultures leads us to a decision to move back up throat cultures to a reference lab and to make the back up throat culture process optional.  That lab will be Child Lab  (http://www.childlab.com/, 1-800-934-6575).

Nearly every child gets a sore throat at some point in their life that makes us wonder, is the child infected with strep?

There are two ways to tell.  Both involve swabbing the back of the throat.  With one of those swabs we do a chemistry reaction in our lab that within 5-10 minutes tells us if any proteins found on the strep germ are on your child's throat.  This is the rapid strep test.

The other way is to take the second swab and rub it on a culture plate.  This is like planting seeds in a garden.  We then wait a day and see if any strep grows.  This is the back up throat culture.

For many years we have used the two tests as follows:

1.  If the rapid strep test is positive, we diagnose your child with strep throat and offer antibiotic therapy.  In this situation there is no need for a back up throat culture.

2.  If the rapid strep test is negative, we make an initial diagnosis that your child does not have strep and has some other cause of their sore throat- usually, but not always, a viral infection.   We have done back up throat cultures in this instance, because the manufacturer of the rapid strep test informs us that a negative test is not 100% reliable.

Over the last 10 years, we have seen the rapid strep perform very, very well, even when negative.  Of course, we do occasionally see someone with a rapid strep test negative on one day, only to have the back up throat culture come back positive.

Recently we have conducted three surveys of just how accurate a negative rapid strep test is.

In the first two surveys, we simply looked at 200 negative rapid strep tests and asked, how many of the back up throat cultures came back positive?   We did this twice.  

In the first run of 200 consecutive negative rapid strep tests, 0 of 200 of were found to have their back up throat culture come back positive.  

In the second run of 200 consecutive negative rapid strep tests, we found 1 of 200 back up throat cultures came back positive.

Then, in August of 2013, we chose one person from each month of the last 2 years who had a back up throat culture, and found in 25 cases reviewed, not one had a positive back up throat culture.

So, out of 400 consecutive throat cultures, one back up was positive.  And in a 2 year review of fairly randomly selected cases, no back up throat culture was positive in that 2 year review.

Put it all together, and the data are compelling.  Yes, some people come back positive after a negative rapid strep test, but it turns out to be a very small number.

The key finding is that if your child is found to have a negative rapid strep test, there is a 99.9975% chance they do not have strep and do not need a back up throat culture.

Because of these findings and increased regulatory requirements to perform throat cultures in a doctor's office setting, we decided to stop doing back throat cultures in our office.

We will still make the back-up throat culture available to your family at the sore throat visit.

But instead of that back up throat culture happening in the office, we will send it out to our reference laboratory, Child Lab.

We have been impressed over the years with Child Lab.  Based out of Nationwide Children's Hospital in Columbus with labs in Cleveland, they only do tests for children.  As such they are the only such lab in our region with special expertise in pediatric lab services.

So, we will continue to use two swabs when we test your child for strep throat.  And we will continue to run the rapid strep test in our office so you can get results in a few minutes.  The back up throat culture, however, will only be done at the family's request, or if your child's history suggests a strong chance of a wrong rapid strep test.

Keep in mind, that if we run a back up throat culture, it will be done by Child Lab.  So we want you to check with your insurer to be sure that will cover a back up throat culture for strep throat at Child Lab.

Their official name is Child Lab, their web page address is http://www.childlab.com/, and their phone number is 1-800-934-6575.

Bottom Line 

The performance of the rapid strep test in our hands is highly reliable.  If positive, we are confident your child has a strep throat.   And, if negative, we are so confident that your child does not have strep throat, we can say that the chance we are right is 99.9975%.   And so we are no longer going to do in office back up throat cultures for negative rapid strep tests.

But, we will continue to offer the back up throat culture to any family that wants that test done, and in those unusual situations where someone has had several positive throat cultures when the rapid strep is positive.

These throat cultures will be sent out to Child Lab, so check with your insurer to make sure that you are covered if we, together, decide your child needs a back up throat culture after a negative strep.

We hope our efforts to improve quality of care continue to advance your child's health, and we continue to appreciate the opportunity to work together to do so.

Dr. Arthur Lavin

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