Physicists at McMaster University in Ontario, Canada, identified a simple mechanism deadly bacteria use to fend off antibiotics, a study published in Nature Communications Biology found.
The researchers looked at how membranes of bacteria interacted with the antibiotic polymyxin B — a drug commonly used to treat urinary tract infections, meningitis, blood and eye infections.
They concentrated on this antibiotic since it was once considered the strongest drug of its kind. Its strength came into question in 2016 after Chinese scientists discovered a gene that let bacteria become resistant to polymyxins.
"We wanted to find out how this bacteria, specifically, was stopping this drug in this particular case," said first study author Adree Khondker. "If we can understand that, we can design better antibiotics."
The study used methods physicists usually employ for materials research to look deeper into the bacterial membrane. By using imaging and simulations, the researchers found the part of the antibiotic that enters the membrane, where it enters and how deeply it penetrates. They simulated these processes on microsecond timescales with high-end gaming computers in their lab.
The team determined that when a bacterium has become resistant, its membrane is more rigid and the charge is weaker, making it less attractive to the drug and harder to penetrate.
"For the drug, it's like going from cutting Jello to cutting through rock," Mr. Khondker explained.
"There has been a lot of speculation about this mechanism," said lead study author Maikel Rheinstädter. "But for the first time we can prove the membrane is more rigid and the process is slowed."