Action of Colloidal Bismuth Hydroxide Gel and its Commercial Cream on Enteropathogens and Colonizers of the Gastrointestinal Tract

Abstract

Background: Acute diarrheal diseases constitute a world public health problem because they are the second cause of death in children under 5 years of age. Colloidal bismuth hydroxide gel (CBHG) is an active ingredient in low-cost, antidiarrhetic drugs for oral use; it does not inhibit intestinal motility, and it features very low intestinal absorption of <1%.

Materials and methods: We analyzed the sensitivity by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC); the effect on bacterial growth by studying the specific growth velocity and the generation time in growth curves; and bacterial attachment by counting viable plaques, of enteropathogenic Escherichia coli, shigatoxigenic E. coli O157:H7, Klebsiella pneumoniae, Salmonella spp., and Shigella flexneri in the commercial cream (Chobet^® bismuth cream with pectin [CBCHP]), its active ingredient (CBHG), and its excipients (E) separately.

Results: CBCHP: MIC 6-10 mg/ml and MBC 7.5-15 mg/ml of bismuth; CBHG: MIC 6-10 mg/ml of bismuth. E: No inhibition was observed at the concentration studied in this study. At very low subinhibitory concentrations of CBCHP and CBHG, there was already evidence of a significant decrease in growth, which could not be recorded for E. CBCHP and CBHG presented an elevated capacity for bacterial displacement, significantly greater than E.

Conclusions: We believed that the results obtained in this study are very promising from the treatment standpoint, as a possible treatment for cases of diagnosis or suspicion of bacterial gastroenteritis. The antimicrobial and attachment effects of CBCHP are exclusively due to its active ingredient CBHG; these effects are promoted in the presence of E.

Keywords: Colloidal bismuth; diarrhea; enteropathogens.

Figure 1

Specific growth velocity (μ) as a function of treatment with the compounds at different concentrations. Bacterial strains: (a) Salmonella spp., (b) Klebsiella pneumoniae, (c) Shigella flexneri, (d) Shigatoxigenic Escherichia coli, (e) Enteropathogenic Escherichia coli, and (f) Escherichia coli ATCC 25922. Compounds: CBCHP: Chobet® bismuth cream with pectin, CBHG: Colloidal bismuth hydroxide gel, E: Excipients. Concentration of bismuth (grayscale): Without bismuth (); 0.06 mg/ml (); 0.12 mg/ml (); 0.3 mg/ml () and 0.6 mg/ml (). *(P < 0.05), **(P < 0.01)

Figure 2

Generation time (G) as a function of treatment with the compounds at different concentrations. Bacterial strains: (a) Salmonella spp., (b) Klebsiella pneumoniae, (c) Shigella flexneri, (d) Shigatoxigenic Escherichia coli, (e) enteropathogenic Escherichia coli and (f) Escherichia coli ATCC 25922. Compounds: CBCHP: Chobet® bismuth cream with pectin, CBHG: Colloidal bismuth hydroxide gel, E: Excipients. Concentration of bismuth (grayscale): Without bismuth (); 0.06 mg/ml (); 0.12 mg/ml (); 0.3 mg/ml () and 0.6 mg/ml (). *(P < 0.05), **(P < 0.01)