Fighting Helicobacter

Oeiras, 30.12.2013

Researchers from the Molecular Genetics of Microbial Resistance Lab have demonstrated that carbon monoxide-releasing molecules (CORMs) are able to kill Helicobacter pylori, a bacterium causing chronic gastric ulcers. The results are just published in PLoS ONE.

Gastric and duodenal ulcers are caused by the bacterium Helicobacter pylori (a Nobel Prize worth revelation) and as such can be treated with antibiotics. Still, sometimes it’s not that simple. The increasing occurrence of antibiotic-resistant H. pylori strains makes treatments more difficult, even if a combination of two or three antibiotics is regularly used. Thus, once acquired, the bacteria establish lifelong infections, which apart from the painful ulcers can cause malignant gastric cancer. Noteworthy, over half of the world population is thought to be infected by these, sometimes asymptomatic, bacteria.

Researchers tested the effect of CORMs in different strains of Helicobacter pylori, including antibiotic resistant strains, and found two CORMs able to inhibit the growth of the bacteria both in vitro and during infection of mammalian cells in culture. The mode of action seems to involve the release of the carbon monoxide, which in turn interferes with the bacteria respiration and with the activity of an enzyme essential for pathogenesis. This bactericidal effect was stronger when CORMs were used in combination with traditional antibiotics.

Antibiotic resistance is less likely to be developed when using multiple bactericidal agents that affect different pathways. So, the ability of CORMs to kill Helicobacter pylori makes them good candidates for fighting antibiotic resistant strains. The benefit of using CORMs might even be double: known for their anti-inflammatory effect, these molecules should help reducing the gastric mucosal inflammation, which is the main cause for the development of malignant lesions. While the tested CORMs concentrations showed to be not toxic to mammalian cells, future tests in mice are mandatory to fully assess the usefulness of these novel antimicrobial compounds.

Original Article

PLOS ONE 10.1371/journal.pone.0083157

The bactericidal activity of carbon monoxide–releasing molecules against Helicobacter pylori

Ana F. Tavares, Margarida R. Parente, Marta C. Justino, Mónica Oleastro, Lígia S. Nobre, and Lígia M. Saraiva