New antibiotics discovered to treat multi-resistant germs

A key challenge in the fight against antibiotic resistance is identifying new antimicrobial agents. Natural compounds produced by fungi and bacteria have been the most important source of new antibiotics in recent decades. However, these microorganisms were recently considered to have been largely explored – including the so-called actinomycetes.

“By employing improved fractionation methods, we have now been able to demonstrate that even well-studied strains of antibiotic-producing actinomycetes can yield new chemical structures with unique mechanisms of action,” says Max Berger, PhD student in the Department of Chemistry at the University of Hamburg and co-first author of the study.

The research carried out by the team from Hamburg, McMaster University in Ontario (Canada) and University of Illinois in Chicago (USA) focused on a bacterium from the actinomycete group.  Streptomyces rimosus is primarily known as the producer of the antibiotic oxytetracycline, which is used, amongst other things, to treat eye infections. The researchers have now succeeded in isolating another previously unknown antibiotic from the bacterium, which they have named manikomycin.

“Manikomycin can kill groups of multi-drug-resistant bacteria and is not susceptible to the resistance patterns associated with clinically used antibiotics,” explains Berger. In initial studies in mice, the new antibiotic demonstrated acceptable tolerability. However, sufficient efficacy has not yet been observed in initial infection models, as the active substance appears to degrade relatively quickly in blood plasma. “The results suggest that insufficient plasma exposure, rather than fundamental inactivity, is responsible for the low efficacy,” says Berger. It is, however, possible that the pharmacological properties of manikomycin could be improved through further research.

Overall, the researchers view the discovery of this new active substance as a significant indication that already known microorganisms continue to hold great potential for the development of novel antibiotics.