More and more bacterial pathogens of infectious diseases become resistant to customary antibiotics. Typical hospital germs such as Escherichia coli and Klebsiella pneumoniae have become resistant to the most – and in some cases even all – currently available antibiotics. Their additional external membrane makes these bacteria difficult to attack. It protects the bacteria particularly well by preventing many substances from getting into the cell interior. Especially for the treatment of diseases caused by these so-called gram negative bacteria, there is a lack of new active substances. An international team of researchers, with the participation of scientists from Justus Liebig University Giessen (JLU), has now discovered a novel peptide, that attacks gram negative bacteria at a previously unknown site of action.