Alternative to antibiotics discovered

Posted by Emma Woollacott

With bacteria increasingly developing resistance to antibiotics, German researchers say they've found a replacement.

The indiscriminate use of antibiotics - in farm animals as well as people - has allowed more and more pathogens to develop immunity to penicillin and other antibiotics. Indeed, the World Health Organization says that if measures are not taken quickly, it may soon not be possible to treat many frequently occurring infections.

Last year, for example, nearly half a million people were infected with an antibiotic-resistant strain of tuberculosis, and one third of those infected died.

But research scientists at the Fraunhofer Institute for Cell Therapy and Immunology IZI say they've found an alternative in the nick of time - antimicrobial peptides.

The team produced sequence variations of familiar fungicidal and bactericidal peptides and tested them in vitro on different microbes.

They then compared the survivability of the pathogens with an untreated control.

"We have already identified 20 of these short chains of amino acids which kill numerous microbes, including enterococci, yeasts and molds, as well as human pathogenic bacteria such as Streptococcus mutans, which is found in the human oral cavity and causes tooth decay," says Dr Andreas Schubert, group manager at Fraunhofer IZI.

"Even the multi-resistant hospital bug Staphylococcus aureus is not immune, and in our tests its growth was considerably inhibited."

Antibiotic peptides deliver their microbicidal effect within a few minutes, says Schubert, and work at a concentration of less than 1µM. Conventional antibiotics require a concentration of 10µM.

"The spectrum of efficacy of the tested peptides includes not only bacteria and molds but also lipid-enveloped viruses," Schubert adds. "Another key factor is that the peptides identified in our tests do not harm healthy body cells."