By Michael Irving

Viruses may be hogging all the headlines at the moment, but it’s important to remember that bacteria are also a looming threat to public health, as they continue to develop resistance to antibiotics. Now a new study has identified a peptide that can make existing antibiotics more effective at a much lower dose.

Antibiotics were one of the most important medical breakthroughs of the 20th century, but while they helped us win the battle for a while, bacteria may yet win the war. The bugs have been playing the long game, slowly but steadily developing resistance to each of our drugs. Fast forward a few decades and we’re down to the last few weapons in our arsenal – and even they won’t hold up for much longer.

New antibiotics are in development of course, but it’s an expensive and time-consuming process and bacteria will again render the final product ineffective in a matter of years. A better plan of attack may be to find ways to reinvigorate existing antibiotics, with past studies finding success by combining old drugs, or weakening bacteria first by shining blue light on them or drilling through their outer membranes.

For the new study, researchers from Örebro and Linköping Universities identified an antibacterial peptide and how it could be put to work. The peptide is known as plantaricin, and is derived from a probiotic bacteria that’s often used as a preservative in foods like pickles and sauerkraut.

The team pitted plantaricin against methicillin-resistant Staphylococcus aureus (MRSA). This superbug, often called “golden Staph,” is a common pest in hospitals that causes infections in wounds or implants that can turn dangerous.

In tests, plantaricin was found to dissolve the bacterial membrane, allowing the drugs to get in and kill the superbugs much more easily. That would give existing, tired drugs a new lease on life, expanding our arsenal and delaying the advance of the superbug. Plus, required dosages are much lower.

“With plantaricin, the doses of antibiotics required to get a sufficient antibacterial effect is 100 times lower than usual,” says Hazem Khalaf, co-lead author of the study. “And lower doses is a good thing since the antibiotics can have toxic side-effects and damage internal organs.”

The team says that plantaricin has shown promise in tests with a variety of different antibiotics. As a bonus, bacteria are unlikely to develop resistance to the peptide itself, according to the researchers.

“The membrane is a basic structure in the bacterial cell, and has been stable during evolution without major changes,” says Torbjörn Bengtsson, co-lead author of the study. “This most likely explains why bacteria do not have the ability to develop resistance to our peptides.”

The researchers say that they plan to incorporate plantaricin into smart wound-dressing materials or coatings for implants, to prevent bacterial biofilms from forming.

The research was published in the journal Nature Scientific Reports.

Source: Örebro University