I think the same principles would apply.

First make sure you have plenty of blood (2 tubes) as you need about a million cells for the best test.

Then look at the quantitative results – were the number of spots exactly the same on both tests?

Finally, again look at that CDC guidance on these tricky situations when you actually may find value in placing a TST. If the TST were negative in your low risk person without exposure, then I’d call it negative.

 

 

 

 

 

Thank you. I was referring to a T-Spot not an IGRA.

 

 

 

Cathy,

By your use of the term “borderline” I’m guessing you use T-Spot. But in case you were using it in a more generic sense, there is a good article by Wendy Thanassi et al delineating a retesting zone for QFT-GIT using the 0.35 – 1.11 IU/ml results. Wendy spoke at our AOHC a couple of weeks ago and shared a helpful algorithm using 1.1 as the cutoff for the first test and 0.7 as the cutoff for the retest. Again, that probably won’t help you much if you are using T-spot.

 

The CDC lists this situation as a time when you might want to do both a TST and an IGRA. If the TST is negative and the person is low risk and the IGRA remains borderline, it’s less like to be an LTBI case than if the TST is positive also.

 

You really should sit down with your medical director and develop a protocol based on the quantitative result, and the specific IGRA you use (T-Spot or QTF-GIT.) Hopefully he or she participates on this listserve also!

 

Here are some references that may be helpful in writing your protocol:

 

http://www.hindawi.com/journals/pm/2012/291294/

https://labmed.oxfordjournals.org/content/45/3/207

http://www.atsjournals.org/doi/abs/10.1164/rccm.201305-0831OC

 

 

 

 

We use Interferon Gamma Release Assays ( IGRA) to test for tuberculosis on all new employees.  I have one new employee that I have tested twice (with approx one month in between testing) and both times the results were borderline.  Has anyone else had this come up and if so what did you do next?  This employee has no symptoms and no high risk activity such as traveling outside the country or having contact with anyone with known Tb.

 

 

Cathy Senior RN BSN CDE

Employee Health Director

Penn Highlands DuBois

100 Hospital Avenue

P.O. Box 447

DuBois Pa 15801

Phone 814-375-3392

Fax 814-372-2610

cesenior@phhealthcare.org

www.phhealthcare.org

 

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This email and any attached files are sensitive in nature and intended solely for the intended recipient(s). If you are not the named recipient you should not read, distribute, copy or alter this email. Any views or opinions expressed in this email are those of the author and do not represent those of Penn Highlands Healthcare or its affiliates.. Warning: Although precautions have been taken to make sure no viruses are present in this email, the company cannot accept responsibility for any loss or damage that arise from the use of this email or attachments.