anti-bacterial effects of bismuth compounds and its synergy with tetracycline and metronidazole on helicobacter pylorl

a bacteriological investigation performed on the biopsies of 1 30 patients with gastrointestinal disorders at the gi section of imam khomeini hospital concluded in the isolation of 100 cases of helicobacler pylori. the antibacterial effects of bismuth salts alone and in synergy with tetracycline and metronidazole were evaluated on the basis of disc diffusion method on 5 randomly selected pure cultures of h. pylori - the main target - and 4 standard cultures of other bacteria including staphylococcus aureus (atcc 25923), brucella abortus (cs bpi- a 10 3) s99, salmonella typhi (cs bpi - 196) 0-90 i and escherichia coli (a tcc 25922) in order to control the accuracy of procedures. in this research, growth inhibition zones by bismuth subcitrate (128 µg/disc potency) were determined as 15 ± 2.4 mm diameter against h. pylori (mean ± so), and 15 ± 2.6, 20±3.1 and 14 ± 2.5 mm against the given standard cultures, respectively, except for e. coli. tetracycline (30 µg potency) produced inhibition zones of 30 ± 2.6 mm against h. pylori and 30 ± 2.4,40 ± 2.9,25 ± 2. 3 and 21 ± 2.8 mm against the standard strains, respectively. diameters of inhibition zones by metronidazole were 4± i against h. pylori, and 3± 1.2, 8±2.4 and 3 ± 1. 3 mm against the standard strains, respectively, except for the resistant e. coli. [n another test in order to demonstrate the synergistic effects of bismuth subcitrate together with the two mentioned antibacterial agents, a composition of 4 parts of bismuth subcitrate, one part tetracycline and 6 parts metronidazole was used (359 µg potency). the obtained data were as follows: the growth inhibition zone againsth. pylori was 40±3 mm and 42±2.2, 45±2.1, 35±2.6 and 27 ±2. 3 mm against the control strains. therefore, these results indicate that bismuth cubcitrate has a remarkable antibacterial effect against h. pylori among the bismuth salts which increases when used together with tetracycline and metronidazole in peptic ulcers.