No abstract

The venom peptide bicarinalin, previously isolated from the ant Tetramorium bicarinatum, is an antimicrobial agent with a broad spectrum of activity. In this study, we investigate the potential of bicarinalin as a novel agent against Helicobacter pylori, which causes several gastric diseases. First, the effects of synthetic bicarinalin have been tested against Helicobacter pylori: one ATCC strain, and forty-four isolated from stomach ulcer biopsies of Peruvian patients. Then the cytoxicity of bicarinalin on human gastric cells and murine peritoneal macrophages was measured using XTT and MTT assays, respectively. Finally, the preventive effect of bicarinalin was evaluated by scanning electron microscopy using an adherence assay of H. pylori on human gastric cells treated with bicarinalin. This peptide has a potent antibacterial activity at the same magnitude as four antibiotics currently used in therapies against H. pylori. Bicarinalin also inhibited adherence of H. pylori to gastric cells with an IC50 of 0.12 μg·mL−1 and had low toxicity for human cells. Scanning electron microscopy confirmed that bicarinalin can significantly decrease the density of H. pylori on gastric cells. We conclude that Bicarinalin is a promising compound for the development of a novel and effective anti-H. pylori agent for both curative and preventive use.

No abstract

Bacterial competitiveness appears to be an efficient way to fight pathogenic oral flora. This competition may be facilitated by probiotics, particularly in periodontal diseases. The aim of this study was to investigate the probiotic properties of 61 clinical isolates of oral lactobacilli.The inhibitory activity of the tested strains against periodontopathogens was assessed with the agar overlay technique. The results obtained, as well as those resulting from previous work, led us to select the nine most promising strains on which we conducted further tests, such as evaluating their coaggregation capacities with various oral species and the production of proinflammatory cytokines by PBMC. We also evaluated the safety of the probiotics by assessing their sensitivity to antibiotics. Their possible involvement in halitosis was investigated by testing their ability to produce volatile sulfur compounds.The results of the agar overlay technique showed that all the lactobacilli strains had an antibacterial activity against Tannerella forsythia, Treponema denticola, and Aggregatibacter actinomycetemcomitans. Fifty-two strains slightly inhibited the growth of P. gingivalis and only two had no activity on F. nucleatum. The nine strains tested did not coaggregate with P. gingivalis, T. forsythia, T. denticola or A. actinomycetemcomitans. Three strains strongly coaggregated with F. nucleatum. Only three strains produced lower IL-6 than the activator at the maximum concentration tested in this study. However, none of the 9 strains produced a greater amount of IL-8 than that obtained with 1 μg/ml of LPS. These results show us that all the strains were sensitive to the antibiotics tested, except for one strain which showed resistance to penicillin. The production of CSV by the strains remained below the threshold of halitosis. Among the 61 strains tested, 9 proved to be of interest including one that was particularly promising.

These in vitro tests confirm the value of chlorhexidine lozenges in the treatment of upper respiratory tract infections such as sore throat.