Anti-borreliae efficacy of Gallic acid in vitro

Authors: Anna Goc, Waldemar Sumera, Aleksandra Niedzwiecki, and Matthias Rath

Presented at: ASM Microbe Online; June 22, 2020

Published in: ASM Microbe 2020 Final Program; Poster # SUNDAY-441

Abstract: Lyme disease, a tick-borne disease caused by Borrelia burgdorferi sensu lato, has become a growing health concern in the USA and Europe. The search for novel non-toxic and effective treatment approaches is still sought after due to the growing number of newly infected patients or those that relapse after discontinuation of antibiotic application. In this study, we investigated whether a trihydroxybenzoic acid known as Gallic acid, and representative of phenolic acid, could become such an alternative. Using microscopic and spectrofluorometric methods against typical motile spirochetes and their knob/round-shaped persisters, we have observed its significant nearly 99% biocidal effect in eliminating both these morphological forms of Borrelia burgdorferi s.s. and Borrelia garinii at 100 µg/ml concentration after 72h of treatment. This effectiveness was compared to a combination of doxycycline, cefoperazone, and daptomycin that showed similar efficacy at 30-50 µg/ml concentration. At the same time 14 day sub-culture experiment performed with cells pre-treated with Gallic acid and triple combination of mentioned antibiotics, respectively, yielded similar, i.e., 3-11% repopulation rate of viable cells. Based on the obtained results, we concluded that Gallic acid is a prospective anti-borreliae agent and might be considered in further in vivo and human studies.