Histamine H1 receptor antagonists enhance the efficacy of antibacterials against Escherichia coli.

H1 receptor antagonists are commonly used for the treatment of allergic diseases. The aim of this study was to find out, if antihistaminic compounds like mepyramine have the ability to influence the activity of antibacterials. Therefore, the checkerboard method was chosen to detect these possible effects in vitro. Studies were performed with two different Escherichia coli (E. coli) strains as test microbes, treated with antibacterials in combination with mepyramine. The minimum inhibitory concentration (MIC) of E. coli ATCC® 25922™ and E. coli PIG 01 was reduced by combinations of the tested antibacterials with mepyramine. These results have to be confirmed in vivo, before the use of antihistamines should be considered as potential way to minimize the amount of used antibacterials for treatment of E. coli infections.