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.

The Addition of a Synthetic LPS-Targeting Domain Improves Serum Stability While Maintaining Antimicrobial, Antibiofilm, and Cell Stimulating Properties of an Antimicrobial Peptide

“…Viable biofilm colonies still remained even after incubation with peptides at concentrations 16 times higher than the MBC of their planktonic counterparts. Other authors have also noted a lack of correlation between Minimal Inhibitory Concentration (MIC) and MBC values and effective biofilm reduction [72], some even reporting anti-biofilm activity at concentrations lower than the MBC [11]. A possible explanation proposed for this phenomena could be related to the fact that bacteria within biofilms operate at a lower metabolic status than their planktonic counterparts [2] and have been observed to be genotypically and phenotypically distinct [73].…”

“…Alternatively, the difference between the MBC of planktonic bacteria and their biofilm-forming counterparts may be due to a loss of peptide after interaction with EPS constituents. Some AMPs have been known to become trapped within the EPS due to the strong attraction between negatively charged EPS components and the cationic charge of AMPs, thus making them devoid of any anti-biofilm activity [72] or degraded by biofilm enzymes. Therefore, in the process of translocating through or disrupting the EPS, some peptide may have been lost in the process.…”

Lactoferrin-Derived Peptides as a Control Strategy against Skinborne Staphylococcal Biofilms

“…Ongoing antibiofilm strategies for the treatment of staphylococcal skin diseases include low-amperage direct electrical current exposure [18], functionalized hydrogels and nanomaterials [17], plant extracts [19,20], bacterial metabolites [21], enzymes [22], and antimicrobial peptides (AMPs [23]). These latter are components of innate immunity system showing several advantages: (a) the broad spectrum of action against Gram-positive and negative bacteria, (b) a lower acquired resistance compared to antibiotics, (c) the synergistic interactions with other antimicrobials [23,24].…”

Optimization of ZnO Nanorods Growth on Polyetheresulfone Electrospun Mats to Promote Antibacterial Properties

“…In this perspective, polymeric nanofibers are often combined with other classes of materials-i.e., inorganic nanostructures and/or organic molecules-to achieve specific deliverable highlights. Combination of polymeric mats with semiconducting oxides, as zinc oxide and titanium oxide (ZnO, TiO2), improves mats performances by adding multifunctionalities such as photocatalytic properties and sensing actions [8,9].Antibacterial properties of fibrous mats are currently under investigation [10-13] to provide innovative materials against bacteria surface contamination that causes severe infection and human health treats: in fact, microorganism colonies-responsible for biofilm formation-are developing an antibiotic resistance that makes this kind of contamination difficult to eradicate.Both Gram-positive and Gram-negative bacteria are able to form biofilms [14], which represent the major causative agent of chronic and recurrent diseases [15,16]: in fact, it is estimated that more than 80% of human infections are biofilm-related [17,18]. In addition, the surfaces of commonly used prosthetic components-such as steel, titanium, and polymeric biomaterial-are susceptible to colonization of biofilm-forming bacterial species [19].…”

“…Both Gram-positive and Gram-negative bacteria are able to form biofilms [14], which represent the major causative agent of chronic and recurrent diseases [15,16]: in fact, it is estimated that more than 80% of human infections are biofilm-related [17,18]. In addition, the surfaces of commonly used prosthetic components-such as steel, titanium, and polymeric biomaterial-are susceptible to colonization of biofilm-forming bacterial species [19].…”