New antibiotic to tackle antimicrobial resistance?

US researchers have found a new antibiotic that can kill antibiotic-resistant bacteria, in mice, without targeting healthy gut bacteria.

The World Health Organization estimates that bacterial antimicrobial resistance (AMR) is directly responsible for more than a million deaths each year, due to misuse and overuse of antibiotics in humans, animals and plants.

A team at the University of Illinois at Urbana-Champaign identified specific drugs, developed by pharmaceutical company and EARA member AstraZeneca, that target a protein transport system (Lol system) in bacteria, which differs genetically between those that cause disease and those that are beneficial, such as those naturally found in the gut.

Currently, antibiotics can target different categories of bacteria, such as gram-negative bacteria, which have a double membrane that makes them harder to kill. However, this means that both infectious and healthy gram-negative bacteria are targeted, damaging the gut microbiome and increasing the risk of health complications.

In the study, published in Nature, the researchers designed different structures of the Lol system and found one variation (lolamicin) could selectively kill a number of infectious gram-negative strains.

When lolamicin was given to mice with drug-resistant septicemia or pneumonia, all the mice with septicemia survived, while 70% with pneumonia survived.

The composition of the gut bacteria in these animals was also not significantly altered, both during the treatment and 28 days after.

First author Kristen Muñoz said: “The mouse microbiome is a good tool for modelling human infections because human and mouse gut microbiomes are very similar.”