Antibiotics, from their discoveries in the 20th century, have become the most important drugs in the history of medicine. Between 1940. and 1962., more than 20 new classes of antibiotics were marketed. Since then, only two new drug classes have reached the market. The first discovered antibiotic, penicilin, has achieved significant success. During his research, Fleming already predicted emergence of resistance to penicilin, and resistance also developed to subsequent antibiotics. Today, resistance apperas to be a global public health issue. Resistance significantly endangers human health. About 33 000 people die every year due to infections caused by resistant bacteria. The growing challenge of antimicrobial resistance and the paucity of novel antibiotics underscore the importance of developing novel therapeutics. Resistance to bacteria can be caused by changes in the genome or by the intake of external DNA. It is well known that veterinary medicine contributes significantly to the emergence of resistance, since antibiotics in animals are used as growth promoters. This has led to the need of developing new approaches to the treatment of bacterial infections. One of the promising approaches is targeting a specific virulence factors, i.e. intercellular comunication systems. Targeting bacterial QS has shown a great potential. Quorum sensing is the ability to detect and to respond to cell population density by gene regulation. Futhermore, AMPs received great attention as a new drug class. These are peptide antibiotics characterized by amphipatic nature derived from their positive charges and hydrophobic amino acid residues. In addition to agents that act on bacteria, the research is also focused on improving the immune system of the host. At present, the greatest potential as an alternative to antibiotics have vaccines, antibodies and bacteriophages. To detect the best way to treat bacterial infections, antimicrobial sensitivity test should be conducted and the type of bacteria that causes the disease to be determined. Since bacterial resistance to antibiotics is not the only issue, but the insufficient development of new antibiotics, the information and knowledge by so far conducted researches could lead to discovery of new drug classes.