CDC Warns of False-Positives with Novel Lyme Disease Culture Test

by lmatthews on May 26, 2014

DNA test sequence for research and scienceLyme disease testing is notoriously challenging with false negatives and false positives occurring with almost every method of testing. This is why the Centers for Disease Control (CDC) works with the US Food and Drug Administration (FDA) to try to give patients, physicians, and clinicians some idea of the accuracy and usefulness of tests for Lyme disease.

Without stringent guidelines for diagnosing Lyme disease many more patients may be misdiagnosed and end up receiving inappropriate treatment. Patients without Lyme disease may be given antibiotics that they do not need and which contribute to increasing levels of antibiotic resistance, in addition to causing undesirable side effects. Alternately, patients with unrecognised Lyme disease may be misdiagnosed instead with arthritis or other condition and be given steroid medications that have the unfortunate effect of suppressing immune function, actually allowing the undiagnosed infection to spread.

False Positives for Lyme Disease Culture

The CDC and FDA have repeatedly warned against the use of tests for Lyme disease that have not been adequately investigated for efficacy and accuracy but in recent weeks they have been looking into a new laboratory-developed test that uses a new kind of culture method to identify the bacteria that causes Lyme disease. This test involves blood samples from patients being cultured in a two-step process and the undergoing immunostaining and possible polymerase chain reaction (PCR) testing. A positive immunostain or PCR result leads to the sample being assessed as culture-positive.

The CDC’s analysis of the new testing procedure had, however, found that there is significant concern over false-positives due to possible laboratory contamination. This could mean that those patients diagnosed with Lyme disease on the basis of this test may be undergoing treatment for a condition they do not actually have, while the true cause of their symptoms remains undiagnosed and untreated.


Approved Lyme Disease Testing

As such, the CDC recommends that any tests used to diagnose Lyme disease be cleared or approved by the FDA. Indeed, laboratories and scientists are encouraged to work with the CDC and FDA when developing any new diagnostic tests for Lyme disease to ensure accuracy and clinical relevance and to gain speedy approval so as to better serve patients.

When looking to see if a specific test for Lyme disease has been approved there may be some confusion as some laboratories have gained certification for Clinical Laboratory Improvement Amendments (CLIA) but not validation for a specific test. The CLIA certification only certifies that a laboratory has met basic standards for quality, not that a test itself is necessarily valid.

How Lyme Disease is Diagnosed

Current testing protocols involve a two-tier assessment using an enzyme immunoassay approved by the FDA followed by a Western Blot or immunoblot test if the first test was positive or equivocal. A positive result on both tests means that Lyme disease is usually diagnosed as these tests look at the body’s reaction to infection with Borrelia burgdorferi rather than simply confirming the presence of DNA fragments of the spirochaetal bacteria. In some cases Lyme disease testing may use PCR methods or culture of tissue samples but these are unable to show active infection and may result in unnecessary treatment.

Reference

Nelson, C., Hojvat, S., Johnson, B., Petersen, J., Schriefer, M., Beard, C.B., Petersen, L., Mead, P. Concerns Regarding a New Culture Method for Borrelia burgdorferi Not Approved for the Diagnosis of Lyme Disease. Morbidity and Mortality Weekly Report. 2014;63(15):333.


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