Geneva researchers find old drug helps fight antibiotic resistance

Antibiotic resistance is a growing problem throughout the world. By 2050, resistance to antibiotics could kill 10 million people a year by one estimate. Keystone / Laurent Gillieron

Researchers from the University of Geneva have found that an anti-herpes drug discovered more than 50 years ago can make it easier for the immune system to attack a common and deadly bacteria.

The bacteria Klebsiella pneumoniae is very common in hospitals, causing many respiratory, intestinal and urinary tract infections. Like many other bacteria, it’s become increasingly resistant to today’s antibiotics. As a result, some strains have been fatal for 40% to 50% of people infected.

A team from the University of Geneva (UNIGE) has now found that edoxudine, an anti-herpes molecule discovered in the 1960s, weakens the protective surface of Klebsiella bacteria and makes them easier for immune cells to attack them. These resultsExternal link were published in the journal PLOS ONE.

“Since the 1930s, medicine has relied on antibiotics to get rid of pathogenic bacteria,” explained Pierre Cosson, professor in the Department of Cell Physiology and Metabolism at the UNIGE Faculty of Medicine, who led the research. “But other approaches are possible, among which trying to weaken the bacteria’s defense system so that they can no longer escape the immune system.”

He adds that this this approach is particularly promising because the strength of the Klebsiella pneumoniae stems largely from its ability to evade attacks from immune cells.

To determine whether the drug had worked to weaken the bacteria’s defenses, the UNIGE scientists used an experimental model based on the amoeba Dictyostelium. This single-cell organism feeds on bacteria by capturing and ingesting them, using the same mechanisms that immune cells use to kill pathogens. “We genetically modified this amoeba so that it could tell us whether the bacteria it encountered were virulent or not,” said Cosson.

This made it possible test thousands of existing drugs and identify those that reduced the bacteria’s strength. The anti-herpes drug edoxudine is interesting in the way it alters the surface layer that protects the bacteria from the external environment.

Unlike an antibiotic, this drug doesn’t kill the bacteria, which “limits the risk of developing resistance, a major advantage of such an anti-virulence strategy,” said Cosson.

The treatment’s effectiveness hasn’t been confirmed in humans but the researchers say the results thus far are encouraging.