Old antibiotics are being revived to fight new threats

"Many work by targeting parts of the bacterium's protective layer that are crucial to its structural integrity, which makes it challenging for bacteria to evolve resistance to these drugs."

"Since the adoption of AMPs in the mid-twentieth century, they have fallen out of use because of their toxicity to humans. As resistance to other antibiotics increases, however, physicians are again having to use AMPs such as polymyxin as a last resort."

"Researchers think that tools such as molecular imaging and computer modelling that weren't around when these drugs were discovered could help to overcome some of the problems that led to AMPs falling out of use. Some scientists are trying to tinker with the design of established peptides such as polymyxin; others are aiming to develop new ones using machine learning."

"In nature, AMPs help microbes to protect themselves against pathogens. Computational biologist Ewa Szczurek, who co-directs the Institute for AI for Health at Helmholtz Munich in Germany, estimates that about 30,000 have been documented. Of these, just a handful have been developed for use as antibiotics or in food preservation."

Bacterial infections that resist many medicines have led physicians to use older antibiotics, including antimicrobial peptides (AMPs). AMPs are small proteins produced by microorganisms, insects, and mammals, often no more than 60 amino acids long. Many AMPs act by attacking parts of a bacterium’s protective layer that are essential for structural integrity, which can make resistance evolution difficult. AMPs fell out of use after mid-twentieth-century adoption due to toxicity concerns for humans. With rising resistance to other antibiotics, AMPs such as polymyxin are again used as last-resort options. Researchers propose re-evaluating AMPs using molecular imaging, computer modelling, peptide redesign, and machine learning to develop new therapies and alternative antibiotic development strategies.

Read at Nature