Antimicrobial Photodynamic Therapy to Control Clinically Relevant Biofilm Infections

Abstract

Biofilm describes a microbially-derived sessile community in which microbial cells are firmly attached to the substratum and embedded in extracellular polymeric matrix. Microbial biofilms account for up to 80% of all bacterial and fungal infections in humans. Biofilm-associated pathogens are particularly resistant to antibiotic treatment, and thus novel antibiofilm approaches needed to be developed. Antimicrobial Photodynamic therapy (aPDT) had been recently proposed to combat clinically relevant biofilms such as dental biofilms, ventilator associated pneumonia, chronic wound infections, oral candidiasis, and chronic rhinosinusitis. aPDT uses non-toxic dyes called photosensitizers (PS), which can be excited by harmless visible light to produce reactive oxygen species (ROS). aPDT is a multi-stage process including topical PS administration, light irradiation, and interaction of the excited state with ambient oxygen. Numerous in vitro and in vivo aPDT studies have demonstrated biofilm-eradication or substantial reduction. ROS are produced upon photo-activation and attack adjacent targets, including proteins, lipids, and nucleic acids present within the biofilm matrix, on the cell surface and inside the microbial cells. Damage to non-specific targets leads to the destruction of both planktonic cells and biofilms. The review aims to summarize the progress of aPDT in destroying biofilms and the mechanisms mediated by ROS. Finally, a brief section provides suggestions for future research.

Revisiting Current Photoactive Materials for Antimicrobial Photodynamic Therapy

“…The inappropriate prescription of antimicrobials or their overuse exacerbates the problem [ 3 ]. The formation of biofilms is also responsible for an increase in the level of microbial resistance [ 4 ]. In fact, several microorganisms, such as bacteria, fungi, green algae, cyanobacteria, and lichen, possess the ability to grow in biofilm form and they are usually incorporated in a matrix of extracellular polymeric substances (EPS) auto-produced by the microorganisms, which makes the penetration of antimicrobial drugs difficult [ 5 , 6 ].…”

“…Photodynamic inactivation (PDI) is an antimicrobial strategy that has been reported as an effective method to inactivate a broad spectrum of pathogens [ 12 , 13 , 14 ], including microorganisms that are highly resistant to conventional antimicrobials [ 15 ] and those that form biofilms [ 4 , 16 , 17 , 18 ].…”

Understanding the Role of Shape and Composition of Star-Shaped Polymers and their Ability to Both Bind and Prevent Bacteria Attachment on Oral Relevant Surfaces

“…The control and reduction of oral biofilm formation [1], initiated by bacterial species living in polymicrobial, pathogenic colonies at or below the gingival margin [2], are critical steps toward the prevention of dental caries and periodontal diseases [3][4][5]. While many methods have been proposed to prevent or treat these biofilms [6][7][8][9][10], one promising strategy is the use of synthetic polymer additives that bind to the tooth surface to act as a barrier or deterrent to the deposition of planktonic bacteria through either lethal [11][12][13] or non-lethal [14,15] mechanisms. Dental materials, especially those delivered from common over the counter products such as toothpaste or mouthwash, must effectively be multifunctional materials in that they must (1) deposit and stick to a tooth surface, (2) act as a barrier against bacteria attachment, (3) be robust against external challenges such as food and drink in order to not require constant reapplication, and (4) perform steps 1-3 in the presence of the salivary pellicle.…”

Characterization and antimicrobial potential of bioactive components of sonicated extract from garlic ( Allium sativum ) against foodborne pathogens

“…It is generally reported that Gram‐positive microorganisms are more sensitive to antimicrobial agents as compared to Gram‐negative ones. Gram‐positive microbes (S. aureus) have thick cell wall (Hu, Huang, Wang, Wang, & Hamblin, ) than Gram‐negative cells ( E. coli ) which can increase the interaction between the garlic active compounds and the structural components. Moreover, cell membrane of Gram‐negative bacteria blocks the penetration of the active compounds which make them resistant.…”