Bacteria such as the "hospital germ" Staphylococcus aureus owe their dangerousness to a double defense: on the one hand, they easily develop resistance to common antibiotics, on the other hand they hide from the immune system. Now a research group led by Jennifer Payne from the Australian Monash University has tested a process that acts against both defense strategies at the same time. It fights the pathogen like a conventional antibiotic and at the same time attracts neutrophils. In turn, these feed cells can attack the bacterium.
In the journal »Nature Communications«, the group explains the details of its approach. The researchers used the antibiotic vancomycin as a basis. It attaches to the cell membranes of Staphylococcus aureus. In order to attract immune cells, they coupled to the vancomycin molecule so-called formylated peptides, fPeps for short, which have long been known to show neutrophils the way to the pathogen.
Usually the food cells are based on FPEPs, which are released by the bacteria themselves. The immune cells always swim in the direction in which the concentration of these short amino acid chains increases. The composite molecule now imitates this process and thus at least partially picks up the camouflage, with which staphylococcus aureus hides from the immune system.
In experiments in the laboratory and on mice, the improved antibiotic has already proven that it fights the dangerous multidrug-resistant Staphylococcus aureus (MRSA) better than vancomycin alone – about twice as well at a dose reduced by a fifth, the researchers write in their study. But they still see their experiments as basic research. It is therefore not expected that human patients will be used in the near future. In order for the hybrid antibiotic to have the desired effect, Payne's group had to carefully optimize the type, length and coupling site for the fPep molecule. A process that is far from complete and must continue to be operated before the active ingredient is ready for use.
