Antiadhesive property of microalgal polysaccharide extract on the binding of Helicobacter pylori to gastric mucin

The emergence of antibiotic-resistant Helicobacter pylori is of concern in the treatment of H. pylori-associated gastroduodenal diseases. As the organism was reported to bind gastric mucin, we used porcine gastric mucin as substrate to assess the antiadhesive property of polysaccharides derived from Spirulina (PS), a commercially available microalga, against the binding of H. pylori to gastric mucin. Results show that polysaccharides prevented H. pylori from binding to gastric mucin optimally at pH 2.0, without affecting the viability of either bacteria or gastric epithelial cells, thus favouring its antiadhesive action in a gastric environment. Using ligand overlay analysis, polysaccharide was demonstrated to bind H. pylori alkyl hydroperoxide reductase (AhpC) and urease, which have shown here to possess mucin-binding activity. An in vivo study demonstrated that bacteria load was reduced by >90% in BALB/c mice treated with either Spirulina or polysaccharides. It is thus suggested that polysaccharides may function as a potential antiadhesive agent against H. pylori colonization of gastric mucin.     

Antimicrobial and antiadhesive properties of a biosurfactant isolated from Lactobacillus paracasei ssp. paracasei A20

Aims: The aim of this study was to determine the antimicrobial and antiadhesive properties of a biosurfactant isolated from Lactobacillus paracasei ssp. paracasei A20 against several micro‐organisms, including Gram‐positive and Gram‐negative bacteria, yeasts and filamentous fungi. Methods and Results: Antimicrobial and antiadhesive activities were determined using the microdilution method in 96‐well culture plates. The biosurfactant showed antimicrobial activity against all the micro‐organisms assayed, and for twelve of the eighteen micro‐organisms (including the pathogenic Candida albicans, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus agalactiae), the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were achieved for biosurfactant concentrations between 25 and 50 mg ml^?1. Furthermore, the biosurfactant showed antiadhesive activity against most of the micro‐organisms evaluated. Conclusions: As far as we know, this is the first compilation of data on antimicrobial and antiadhesive activities of biosurfactants obtained from lactobacilli against such a broad group of micro‐organisms. Although the antiadhesive activity of biosurfactants isolated from lactic acid bacteria has been widely reported, their antimicrobial activity is quite unusual and has been described only in a few strains. Significance and Impact of the Study: The results obtained in this study regarding the antimicrobial and antiadhesive properties of this biosurfactant opens future prospects for its use against micro‐organisms responsible for diseases and infections in the urinary, vaginal and gastrointestinal tracts, as well as in the skin, making it a suitable alternative to conventional antibiotics.     

Treatment of Helicobacter pylori infection using a novel antiadhesion compound (3'sialyllactose sodium salt). A double blind,placebo-controlled clinical study

Background and Aim. 3′ sialyllactose sodium salt (3′SL) is an oligosaccharide that occurs naturally in human and bovine milk. It can inhibit the adhesion of H. pylori to human epithelial cells in vitro. The aim of this study was to test whether this oligosaccharide can suppress or cure H. pylori colonization in vivo and to determine its safety in humans. Methods. Seventy‐one consecutive dyspeptic patients with H. pylori infection documented by histology and ¹³C‐Urea Breath Test (UBT) were initially recruited to this study. Patients with UBT values < 15 were excluded, thus reducing the enrolment to 65 patients. They were given two different dosages of 3′SL (10 g or 20 g/day) in three daily administrations before meals or placebo for 4 weeks, according to a randomised double‐blind protocol. A standardized ¹³C‐UBT (using 100 mg of ¹³C labelled urea) was repeated in all patients at fixed intervals during treatment (at the end of weeks 1, 2 and 4) and 4 weeks after treatment withdrawal. Patients compliance and side‐effects were evaluated at each weekly visit. Results. Five patients were excluded from the PP analysis due to violation of the protocol (noncompliance, lost to follow‐up), whereas 61 patients completed correctly the study: 17 received 3′SL 10 g/day, 22 were treated with 3′SL 20 g/day and 21 were given placebo. The three treatment groups did not significantly differ in demographic or clinical patient characteristics. No serious adverse events were observed during therapy in any of the three groups. No patients became UBT negative (< 4) during or after treatment but UBT values decreased significantly during the study period in both treatment groups and placebo. Conclusions. Antiadhesive therapy was safe and well tolerated but did not suppress or cure H. pylori colonization in humans. The observed decrease in UBT values could be explained by a regression towards the mean effect.