Chitosan Inhibits Helicobacter pylori Growth and Urease Production and Prevents Its Infection of Human Gastric Carcinoma Cells

This study investigated the effects of shrimp chitosan with 95% degree of deacetylation (DD95) in combination with clinical antibiotics on the growth and urease production of Helicobacter pylori. The inhibitory effect of DD95 on the adherence of H. pylori to the human intestinal carcinoma cells (TSGH9201) was also investigated. Five strains of H. pylori, including three standard strains and two strains of clinical isolates were used as the test strains. The inhibitory effects of DD95 on growth and urease production of various strains of H. pylori increased with increasing DD95 concentration and decreasing pH values from pH 6.0 to pH 2.0. Urease activity of H. pylori at pH 2.0 in the presence of 4000 mu g/mL of DD95 decreased by 37.86% to 46.53%. In the presence of 50 mu g/mL antibiotics of amoxicillin, tetracycline, or metronidazole at pH 6.0 and pH 2.0, H. pylori counts were decreased by 1.51-3.19, and 1.47-2.82 Log CFU/mL, respectively. Following the addition of 4000 mu g/mL DD95 into the 50 mu g/mL antibiotic-containing culture medium with pH 6.0 and pH 2.0, overall H. pylori counts were strongly decreased by 3.67-7.61 and 6.61-6.70 Log CFU/mL, respectively. Further, DD95 could inhibit the adherence of H. pylori on TSGH 9201 cells, as evidenced by fluorescent microscopy and thus may potentially protect against H. pylori infection.