## 2 Characterization of Bacterial Biofilms
### Alternative Strategies for Combating Bacterial biofilms  
So far, several alternative strategies (different than antibiotic therapy) to combat biofilms have been proposed (Figure 3). One such strategy is based on surface modification or coating methods which lead to difficulties of microorganism attachment. By using the materials resistant to microbial adhesion and incorporating antimicrobial agents (antiseptic, antibiotics, or metals) onto the surface, biofilm formation is impeded [15; 30; 55]. This approach may be exemplified by interesting applications in medicine where bacterial infections associated with medical devices state a significant problem. Antibiotic metal-based coatings have been developed using silver, titanium, zinc, and copper ions. Metals are applied in order to destroy bacterial integrity and to prevent the proliferation of bacteria on the surface of various medical devices [56]. The main limitation of the metal-based strategy is the concentration of metallic ions, as it should not induce cytotoxic effects. To overcome this primary limitation, different capping agents, e.g., Kocuran, polyethylene glycol (PEG)-heparin hydrogels, and \(\beta\)-cyclodextrintrin (\(\beta\)-CD), have been applied [56]. In another coating approach, [PERSON] and collaborators [57] showed that nitrofurazone-impregnated catheters significantly reduced the biofilm cell counts of _E. faecalis_ and completely inhibited the biofilm-forming ability of _P. aeruginosa_ and _S. epidermidis_. Interestingly, in comparison to hydrophilic or silver-coated catheters, nitrofurazone-impregnated tubes showed more prolonged antimicrobial durability [57]. Another example of a surface-coating material is bioactive glass. [PERSON] et al. presented that titanium implants coated with F18 bioactive glass (F18 BG) had improved antib Biofilm activity in comparison to titanium, especially in the initial periods of biofilm formation by _Candida albicans_, _P. aeruginosa_, and _S. epidermidis_[58]. Recent studies also indicated the application of bioactive glass as a vehicle for the controlled release of therapeutic molecules [59]. Pillararene-based multilayers used for the delivery and release of antibiotics showed similar properties. As indicated, the use of decacarboxylation-pillar(5)arene/poly(allylaminehydrochloride) 8 ((WP5/PAH)8) multilayered films loaded with levofloxacin and amikacin reduced the adhesion and proliferation of _P. aeruginosa_ and _S. aureus_ cells [60]. Undoubtedly, the use of surfaces capable of preventing or reducing bacterial biofilm formation is one of the important strategies in the fight against bacterial biofilms, especially applicable in the fabrication of medical equipment. It is difficult to indicate their superiority over antibiotics or phage-derived depolymerases, as the coating materials serve frequently as multiple drug reservoirs able to release antibacterial agents. Interestingly, direct action on the matrix components, using enzymes, such as deoxyribonuclease I or dispersion B [61], chelators of divalent cations [62], or unsic acid  
Figure 3: Alternative strategies in the fight against mature biofilm or its formation. Circles show the diverse antib Biofilm agents with examples provided. The most common way of treating biofilm infection is the disposal of the contaminated device (e.g., medical equipment implanted) or the removal of formed biofilm [33]. reducing various sugars in EPS, can be classified as an alternative method in the fight against bacterial biofilm upon its establishment [63]. It is worth mentioning that naturally occurring host defense ( antimicrobial) peptides (HDPs), or their synthetic derivatives, also represent an appealing source for generation of promising therapeutic agents for the treatment of persistent infection caused by biofilms formed by drug-resistant Gram-negative and Gram-positive bacteria, such as _E. faecium, S. aureus, K. pneumoniae, A. baumannii, P. aeruginosa, E. coli, L. monocytogenes, and S. enterica_[64; 65].