Lyme borreliosis , caused by Borrelia burgdorferi sensulato, may lead to long-term tissue infection, which may be difficult to cure. The outcome of Lyme borreliosis is highly dependent on the antibiotic treatment . The observation of the ability of B. burgdorferi sensu lato to convert (and reconvert) to cystic forms [3–5] may explain why the infection sometimes is persistent and reactivating.
Therefore, it might be important to eradicate all germative forms (not only the motile form) of the bacterium to obtain a proper treatment for Lyme borreliosis. Grapefruit-seed extract (GSE) contains bioactive flavenoids (e.g., hesperitin, resveratrol, and naringenin) and has been shown to possess anti-microbiological effect against bacteria and fungus [6, 7].
Many studies indicate that GSE is a substance whose therapeutic effect ranks equal to or better than other known anti-bacterial agents. Positive effects of GSE are decreased levels of TNF-?, Nuclear factor Kb, NO, protection of the gastrointestinal tract against mechanical stress, and has anti-allergic and other antioxidative properties [8, 9]. Naringenin, hesperidin and other citrus flavones have been found in plasma and tissue after ingestion .
Lactobacillus and bifidobacteria in the gut seems to be insignificantly affected by GSE , and no severe side effects have been observed. B. burgdorferi sensu lato has a gene for efflux mechanism which may be responsible for antibiotic resistance . GSE is an efflux inhibitor, which can be used to enhance the activity of antibacterial agents .
For the reasons mentioned above it is reasonable to test the hypothesis that motile and cystic forms of B. burgdorferi sensu lato will be susceptible to GSE, and this is the aim of our study.