Antimicrobial peptides for the control of biofilm formation

Antimicrobial peptides (AMPs) are an abundant and varied group of molecules recognized as the most ancient components of the innate immune system. They are found in a wide group of organisms including bacteria, plants and animals as a defense mechanism against different kinds of infectious pathogens. Over the past two decades, a fast-growing number of AMPs have been identified/designed and their wide-spectrum antimicrobial activity has been deeply investigated. In recent years, there has been an increasing interest in the use of AMPs as alternative anti-biofilm molecules for the control of biofilm-related infections. Biofilms are sessile communities of microbial cells embedded in a self-produced matrix and characterized by a low metabolic activity. Due to their peculiar physiological properties, bacteria/fungi in biofilms result more resistant to conventional antibiotic therapies compared with their planktonic counterparts. AMPs may be a promising strategy to combat biofilm-related infections, as many of them target the microbial membrane, thus being potentially effective also on metabolically inactive cells. Investigations conducted so far evidenced that these peptides may be active in either eradicating established biofilms or preventing their formation, depending on the specific molecule. Here we present a detailed review of the literature describing the latest results of both in vitro and in vivo experiments aimed at evaluating AMP potential usage in biofilm control. In addition, we provide the reader with an overview on AMP local delivery systems, and we discuss their potential application in the coating of medical indwelling devices.