Since penicillin and salvarsan were discovered, a number of new drugs to combat infectious diseases have been developed, but at the same time, the number of multi-resistant microorganism strains is increasing. Thus, the design of new and effective antibacterial, antiviral and antifungal agents will be a major challenge in the next years. This book reviews the current state-of-the-art in antimicrobial research and discusses new strategies for the design and discovery of novel therapies. Topics covered include the use of genetic engineering, genome mining, manipulation of gene clusters, X-ray and neutron scattering as well as the antimicrobial effects of essential oils, antimicrobial agents of plant origin, beta-lactam antibiotics, antimicrobial peptides, and cell-wall-affecting antifungal antibiotics.