Approcci antimicrobici basati sulla luce per controllare la crescita di microrganismi patogeni

According to the World Health Organization, drug-resistant bacteria will cause 10 million deaths per year by 2050 if no action is taken. Moreover, the treatment of chronic infections is complicated by microbial biofilms, communities in adhesion to tissues or inert devices that are tolerant to common antimicrobial agents. In this scenario, the interest in adjuvant antimicrobial and antibiofilm approaches are compelling goals to address. Herein, two light-based approaches have been investigated: antimicrobial Photodynamic Therapy (aPDT) and antimicrobial Blue Light Therapy (aBLT). The first technique (aPDT) generates a photooxidative stress upon administration of specific drugs (photosensitizers – PSs) followed by visible light irradiation. The second approach (aBL) exploits blue light to cause cell death thanks to the activation of putative endogenous photosensitizers. In this thesis, a screening of PSs belonging to the families of diaryl-porphyrins and BODIPYs was aimed at the photoinactivation of three microbial pathogens well known for their increase resistance to antimicrobials: the Gram-negative Pseudomonas aeruginosa, the Gram-positive Staphylococcus aureus, and the yeast Candida albicans. Furthermore, in-depth investigations of aBLT were performed on P. aeruginosa biofilm and its main components: bacterial cells, proteins, extracellular DNA, and virulence factors. This study supports the potential role of visible light in controlling the spread of microbial pathogens. Indeed, the combination of antibiotics or antifungals with light-based strategies represents a promising tool of the next-generation anti-infectives