Antibiotics have long been an effective treatment for bacterial infections. The creation of drugs like penicillin, streptomycin, and tetracycline allowed doctors to treat common bacterial infections that were once debilitating and even fatal. As the use of antibiotics has expanded in recent decades, bacteria have developed patterns of resistance that have rendered some antibiotics useless. As these “superbugs” have become more resilient and resistant to treatment, researchers have begun to explore new ways to treat infections. Research has turned to the use of antimicrobial peptides as an alternative to traditional antibiotics in the treatment of drug-resistant bacteria. Antimicrobial peptides, also called defensins, are short chains of amino acids that act against microorganisms. In plants and animals, these peptides consist of 15 to 45 amino acid residues, and they are generally cationic, meaning they contain higher amounts of lysine and arginine (Hancock and Lehrer 82) . Peptides are produced as part of the body's innate immune system and may be present or produced continuously in response to injury or infection. Since antimicrobial peptides are incorporated into innate immunity and are considered part of the body's second line of defense against infections, they are often found in areas likely to be in close contact with infectious agents. environmental pathogens. These areas include “the skin, ears and eyes, on epithelial surfaces including the tongue, trachea, lungs and intestine, and in the bone marrow and testes” (Hancock and Scott 8856). Antimicrobial peptides fall into two broad categories. based on the length of peptide sequences between cysteine ​​residues, with the subfamilies of - and ...... middle of paper ......a? Nature Reviews Microbiology 3.3 (2005): 238-250. Academic research completed. Web.10 April 2014. Ganz, Thomas. “Defensins: antimicrobial peptides in innate immunity.” Nature Reviews Immunology 3.9 (2003): 710-720. Academic research completed. Internet. April 10, 2014. Hancock, Robert EW and Monisha G. Scott. “The role of antimicrobial peptides in animal defenses.” Proceedings of the National Academy of Sciences of the United States of America 16.97 (2000): 8856-8861. Google Scholar. Internet. April 10, 2014. Hancock, Robert EW and Robert Lehrer. “Cationic peptides: a new source of antibiotics. » Trends in Biotechnology 16 (1998): 82-88. Google Scholar. Internet. April 10, 2014. Reddy, KVR, RD Yedery, and C. Aranha. “Antimicrobial peptides: premises and promises”. International Journal of Antimicrobial Agents 24 (2004): 536-547. Google Scholar. Internet. April 10 2014.