In vitro anti-Helicobacter pylori activity of ebrotidine

The in vitro anti-Helicobacter pylori (H. pylori) activity of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene) amino]-4-thiazolyl]methyl]thio]ethyl]amino]methylene]-4-bromo- benzenesulfonamide, CAS 100981-43-9, FI-3542) versus ranitidine, and their effect on the susceptibility to the antimicrobial agents used in H. pylori eradication were investigated. Assessment was performed by determining the minimum inhibitory concentrations (MIC) against 9 strains of H. pylori, 8 from clinical source and 1 from the American Type Culture Collection (ATCC 43504), in Mueller-Hinton solid media plus 7% blood. The concentration of inocula was 10(7) CFU/ml, incubation was performed at 37 degrees C in microaerophilic atmosphere, and results were read after 5 days of growth. Ebrotidine gave a mean MIC value of 75 micrograms/ml, while that for ranitidine was > 1000 micrograms/ml. Ebrotidine at 100 micrograms/ml enhanced the activity of the antimicrobials studied as follows: erythromycin 3 times, tetracycline 1.1 times, amoxicillin 3 times, metronidazole-sensitive strains 9 times and clarithromycin 5 times. Ranitidine had no effect on the MIC of the antibiotics even at 500 micrograms/ml.