Biofilms: Novel Strategies Based on Antimicrobial Peptides

Abstract

The problem of drug resistance is very worrying and ever increasing. Resistance is due not only to the reckless use of antibiotics but also to the fact that pathogens are able to adapt to different conditions and develop self-defense mechanisms such as living in biofilms; altogether these issues make the search for alternative drugs a real challenge. Antimicrobial peptides appear as promising alternatives but they have disadvantages that do not make them easily applicable in the medical field; thus many researches look for solutions to overcome the disadvantages and ensure that the advantages can be exploited. This review describes the biofilm characteristics and identifies the key features that antimicrobial peptides should have. Recalcitrant bacterial infections caused by the most obstinate bacterial species should be treated with a strategy to combine conventional peptides functionalized with nano-tools. This approach could effectively disrupt high density infections caused by biofilms. Moreover, the importance of using in vivo non mammalian models for biofilm studies is described. In particular, here we analyze the use of amphibians as a model to substitute the rodent model.

Keywords: anti-biofilms peptides; biofilm in vitro; biofilm in vivo; nanotechnology.

Figure 1

Biofilms develop in three phases: initial adhesion, maturation, and dispersion. A good anti-biofilm agent (blue peptide) can be involved in all the biofilm phases. AMPs may inhibit the accumulation of bacteria on the surface by interacting with their adhesion proteins (red and light blue) or coating the surface to protect from bacterial attack. Antimicrobial peptides can display an action against bacteria in their active state in the biofilm (brown); they can also defeat bacteria in the persisters models (yellow) or interfere with life processes such as synthesis of EPS (light green matrix), signaling compounds (triangle), extracellular DNA, and proteins (green helix).

Figure 2

Coating of nanoparticles with antimicrobial peptides is a promising strategy to overcome the drawbacks of the nanoparticles and peptides themselves and improve their action with a synergistic effect. Moreover, the conjugation may affect the peptide properties and the design of new antimicrobial nanomaterials is required.