Lab test adapted to identify new Lyme treatments

A research team from Johns Hopkins Bloomberg School of Public Health has developed a rapid antibiotic susceptibility test to evaluate the effect of potentially thousands of FDA-approved drugs against Borrelia burgdorferi, according to a report published in PLOS One.

Ying Zhang, MD, PhD, professor in the Bloomberg School’s department of molecular microbiology and immunology, and colleagues developed the SYBR Green I/PI assay — normally used for staining DNA in samples — to identify new treatments for lingering bacteria, or “persisters,” in Lyme patients who have completed the standard antibiotic regimen. The diagnosis of post-treatment Lyme disease syndrome (PTLDS) has been controversial in the field of infectious disease.

Ying Zhang

According to the researchers, doxycycline and amoxicillin are considered the most effective antibiotic treatments against early infection with B. burgdorferi, but a subset of Lyme patients who complete the standard treatment course — as high as 20% — experience PTLDS.

In a previously published study in Emerging Microbes and Infections, Zhang and colleagues used the modified test, which stains living bacteria green and dead or dying bacteria red, to quantify the viability of B. burgdorferi against a range of FDA-approved drugs. The researchers identified 165 agents indicated for other conditions that had demonstrated greater activity than frontline antibiotics against B. burgdorferi persisters.

Unlike the LIVE/DEAD BacLight assay — considered the gold standard for measuring the viability and antibiotic susceptibility of B. burgdorferi — the SYBR Green I/PI assay does not require the bacteria to be washed. Additionally, the test can screen thousands of drugs simultaneously.

For the current analysis, Zhang and colleagues compared SYBR Green I/PI with several other B. burgdorferi viability assays, including the MTT and XTT assays, the fluorescein diacetate assay, Sytox Green/Hoechst 33342 assay, and the LIVE/DEAD BacLight assay. They said the SYBR Green I/PI was superior in demonstrating bacterial viability and susceptibility in terms of accuracy, convenience, low background interference, and speed.

Zhang said he has been contacted by numerous health care professionals interested in the modified test.

“We developed a new SYBR Green/PI assay that is more sensitive, efficient, and less expensive than the current gold standard for testing Borrelia viability and antibiotic susceptibility,” Zhang told Infectious Disease News. “As a result, this new test allowed us to do high throughput drug screens that the current test could not.”

However, Zhang cautioned against prescribing drugs off-label to treat persistent Lyme disease symptoms until animal studies have been conducted, as inappropriate antibiotic prescribing can be highly problematic.

“There are a significant number of people who are sick and desperate for a cure for their Lyme disease symptoms months and even years after they have been told they are cured of the disease,” Zhang said in the release. “The current drugs we use aren’t good enough for these persistent cases. This is why I have been getting so many calls and emails about our test and the drugs we have identified.” — by John Schoen

For more information:

Feng J. PLoS One. 2014;doi:10.1371/journal.pone.0111809.

Feng J. Emerg Microbes Infect. 2014;doi:10.1038/emi.2014.53.

Disclosure: The researchers report no relevant financial disclosures.