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Antibiotic gel helps prevent Lyme disease after tick bite

An antibiotic gel based on azithromycin, an antibiotic with antibacterial properties, helps to prevent the onset of Lyme borreliosis following a tick bite, found a multi-centre international study.

In addition to the Medical University of Vienna, Austrian partners involved in the Phase II/III study, which now only has to be followed by a verification study in order to be potentially put into clinical use, were the Medical University of Graz (department of dermatology), the Medical University of Innsbruck (department of dermatology and venerology), the Elisabethinen Hospital in Linz and the Centre for Travel Medicine in St Pölten. Other study partners come from Germany (Berlin, Würzburg) and Switzerland (Zürich).

The antibiotic gel was developed by the Swiss company Ixodes AG.

A total of 1,000 patients with fresh tick bites were treated with the antibiotic gel within 72 hours of being bitten. Says Jilma: "None of the test subjects went on to develop Lyme borreliosis." Conversely, in the control group that received a placebo, there were seven cases of borreliosis.

The advantage of the gel is that it has no side-effects and, according to the promising results, can therefore also be used for children. Moreover, treatment is very simple: the gel has to be applied every 12 hours over a period of three days. "This kills off the borrelia," explains Jilma.

In Austria, there are around 24,000 cases of Lyme disease every year, while in Western Europe the annual figure is more than 200,000 new cases of the world's most common tick-borne infectious disease. If the infection goes untreated, it can attack a person's joints, heart and nervous system and lead to serious complications. Up to 5% of all tick bites result in Lyme disease: around 20% of ticks are infected.

Summary
Background: Lyme borreliosis develops in 1–5% of individuals bitten by ticks, but with a diagnostic gap affecting up to 30% of patients, a broadly applicable pharmacological prevention strategy is needed. Topical azithromycin effectively eradicated Borrelia burgdorferi sensu lato from the skin in preclinical studies. We assessed its efficacy in human beings.
Methods: In this randomised, double-blind, placebo-controlled, multicentre trial done in 28 study sites in Germany and Austria, adults were equally assigned to receive topical 10% azithromycin or placebo twice daily for 3 consecutive days, within 72 h of a tick bite being confirmed. Randomisation numbers, which were stratified by study site, were accessed in study centres via an interactive voice-response system, by pharmacists not involved in the study. The primary outcome was the number of treatment failures, defined as erythema migrans, seroconversion, or both, in participants who were seronegative at baseline, had no further tick bites during the study, and had serology results available at 8 weeks (intention-to-treat [ITT] population). This study is registered with EudraCT, number 2011-000117-39.
Findings: Between July 7, 2011, and Dec 3, 2012, 1371 participants were randomly assigned to treatment, of whom 995 were included in the ITT population. The trial was stopped early because an improvement in the primary endpoint in the group receiving azithromycin was not reached. At 8 weeks, 11 (2%) of 505 in the azithromycin group and 11 (2%) of 490 in the placebo group had treatment failure (odds ratio 0·97, 95% CI 0·42–2·26, p=0·47). Topical azithromycin was well tolerated. Similar numbers of patients had adverse events in the two groups (175 [26%] of 505 vs 177 [26%] of 490, p=0·87), and most adverse events were mild.
Interpretation: Topical azithromycin was well tolerated and had a good safety profile. Inclusion of asymptomatic seroconversion into the primary efficacy analysis led to no prevention effect with topical azithromycin. Adequately powered studies assessing only erythema migrans should be considered. A subgroup analysis in this study suggested that topical azithromycin reduces erythema migrans after bites of infected ticks.

Authors
Michael Schwameis, Thomas Kündig, Gustave Huber, Luzi von Bidder, Lorenz Meinel, Roland Weisser, Elisabeth Aberer, Georg Härter, Thomas Weinke, Tomas Jelinek, Gerd Fätkenheuer, Uwe Wollina, Gerd-Dieter Burchard, Roland Aschoff, Ruth Nischik, Gerhard Sattler, Georg Popp, Wolfgang Lotte, Dirk Wiechert, Gerald Eder, Olga Maus, Petra Staubach-Renz, Andrea Gräfe, Veronika Geigenberger, Ingomar Naudts, Michael Sebastian, Norbert Reider, Ridwan Weber, Marc Heckmann, Emil C Reisinger, Georg Klein, Johannes Wantzen, Bernd Jilma

[link url="https://www.sciencedaily.com/releases/2016/12/161220093939.htm"]Medical University of Vienna material[/link]
[link url="http://www.thelancet.com/journals/laninf/article/PIIS1473-3099(16)30529-1/abstract"]The Lancet Infectious Diseases article summary[/link]

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