(Datum: 19.September 2011)
Knauer J, Krupka I, Fueldner C, Lehmann J, Straubinger RK. "Evaluation of the preventive capacities of a topically applied azithromycin formulation against Lyme borreliosis in a murine model." J Antimicrob Chemother. 2011 Sep 15.
Our data indicate that topical treatment with a formulation containing azithromycin is a promising approach to prevent Lyme borreliosis shortly after a tick bite.
Details: Laboratory mice were challenged with Borrelia burgdorferi sensu stricto by needle inoculation or via infected ticks as vectors. Then, an azithromycin-containing formulation was applied once daily to the sites of exposure for three consecutive days. In the case of needle inoculation, a 5% azithromycin formulation was applied starting 1 h, 3 days and 5 days after infection.
In the case of tick exposure, 4%, 10% and 20% azithromycin formulations were applied, starting directly after the detachment of the engorged ticks. Concentrations of azithromycin in murine skin were >3800-fold higher than the published minimal inhibitory concentration for B. burgdorferi as soon as 3 h after the first application.
After needle inoculation, spirochaetes were not detectable in all infected mice after treatment, if the first application started 1 h or even after 3 days post-infection.
Furthermore, no borrelial organisms were detected after topical treatment when ticks were used for spirochaete inoculation.
Thanks for posting this. I saw a very high level description of this gel in a magazine last year, and it is good to get a little more specifics.
My concern about the study is how long did they wait before they examined the mice for spirochetes? There have been criticisms of other studies that stopped too soon, declaring the mice healthy, when perhaps if they waited longer, an infection would have eventually shown up. Taking insufficient abx early in the disease often results in a delayed illness onset as the surviving bugs go into hiding for a while. A small number of dormant bugs could be missed in a necropsy.
My other concern is that I am pretty sure I remember reading about another mouse study that found borrelia in the brain within 24-48 hours after infection. I don't know if they were tick infected or needle injected; that might make a difference. If the bacteria are already beyond the skin at the bite area within a day or two, a topical abx wouldn't be sufficient.
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