Inhibitory effect of Lactobacillus acidophilus on Helicobacter pylori in peptic ulcer patients: in vitro study.

ABSTRACT

Lactobacillus acidophilus (L. acidophilus) have been introduced into many fermented dairy products. The presence of L. acidophilus appears to decrease Helicobacter pylori (H. pylori) density in the human stomach and could enhance antibiotic therapy for H. pylori eradication. This study was designed to determine the optimal density of L. acidophilus that has a maximum inhibitory effect on H. pylori in peptic ulcer patients. To determine whether L. acidophilus has an inhibitory effect on H. pylori isolated from peptic ulcer patients and to determine whether the optimal density of L. acidophilus has a maximum inhibitory effect on H. pylori isolated from peptic ulcer patients. H. pylori was isolated from gastric biopsy specimens of peptic ulcer patients. The suspension of pure H. pylori colonies were inoculated into the broth and adjusted to match the density of No.3 MacFarland standard (approximately 9x10(8) cells/ml). Forty microliters of the suspension were equally spread onto each quadrant of the plate and left to dry. L. acidophilus was prepared from LC-1 (Nestle Research Center, Switzerland). They were grown on blood agar and incubated overnight at 37 degrees C. The suspension of L. acidophilus was inoculated into the broth and adjusted to match the density of No.1, No.2, No.3 and No.4 MacFarland standard (approximately 3x10(8), 6x10(8), 9x10(8) and 12x10(8) cells/ml respectively). Ten microliters of each density of L. acidophilus was dropped onto each quadrant of a previously inoculated H. pylori plate and then the plate was kept under microaerophilic conditions for 72 hours. Inhibition clear halo zone of H. pylori around the colonies of L. acidophilus was interpreted as the inhibitory effect. H. pylori were isolated from gastric biopsy specimens of fifteen peptic ulcer patients (eleven patients with gastric ulcer and four patients with duodenal ulcer). A total of sixty tests of inhibitory effect of L. acidophilus on H. pylori were evaluated in the present study. L. acidophilus had inhibitory effect on H. pylori in 13/15 patients (86.67%) and L. acidophilus in the density of No.3 MacFarland standard had a significantly higher inhibitory effect on H. pylori in the density of No.3 MacFarland than that of No.1 (60% vs 20%; p<0.05), No.2 (60% vs 20%; p<0.05) and No.4 (60% vs 20%; p<0.05) MacFarland standard. In conclusion, L. acidophilus has an inhibitory effect on H. pylori isolated from peptic ulcer patients. Approximately an equal density of L. acidophilus on H. pylori has the most favorable effect. This optimal density of L. acidophilus should have maximum effect on H. pylori clearance and could enhance antibiotic therapy for H. pylori eradication in humans.