Development of new antibiotics is declining whereas antibiotic resistance is rising, heralding a post-antibiotic era. Antimicrobial peptides such as gramicidin S (GS), exclusively topically used due to its hemolytic side-effect, could still be interesting as therapeutic compounds. By modifying the amino-acid composition of GS, we synthesized GS analogues. We now show that derivative VK7 has a lower MIC (7.8–31.2 μg/ml, median 15.6 μg/ml) against strains of multi-drug resistant (MDR) Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa than GS has (3.9–62.5 μg/ml, median 31.3 μg/ml). Low MICs for both VK7 and GS were observed for Staphylococcus aureus and Enterococcus faecium. VK7 showed reduced haemolysis and less lactate dehydrogenase release. All compounds were fully bactericidal at MIC values. Modification of GS enables production of novel derivatives potentially useful for systemic treatment of human infections.

dx.doi.org/10.1007/s10096-016-2595-y, hdl.handle.net/1765/91142
European Journal of Clinical Microbiology & Infectious Diseases: an international journal on pathogenesis, diagnosis, epidemiology, therapy, and prevention of infectious diseases
Department of Medical Microbiology and Infectious Diseases

Swierstra, J.W, Kapoerchan, V, Knijnenburg, A, van Belkum, A.F, & Overhand, M. (2016). Structure, toxicity and antibiotic activity of gramicidin S and derivatives. European Journal of Clinical Microbiology & Infectious Diseases: an international journal on pathogenesis, diagnosis, epidemiology, therapy, and prevention of infectious diseases, 35(5), 763–769. doi:10.1007/s10096-016-2595-y