Antimicrobial Blue Light Photoinactivation of Lung Infections

Lung infections are a major threat to global health, particularly for the young, the elderly, the immunocompromised, and the patients with pre-existing lung conditions such as cystic fibrosis. Among pathogens, a wide range of bacterial species are responsible for both acute and chronic lung infections, which are becoming increasingly difficult to treat due to the rise and spread of multidrug-resistant (MDR) bacterial strains, largely caused by the misuse and overuse of antibiotics. In the lungs, bacteria grow as biofilms, which are highly resistant to antibiotics action, notably due to the low penetration of antimicrobials through the biofilm layers and the slowed growth of bacterial cells. Additionally, biofilms help bacteria evade the host immune system by preventing bacterial clearance by immune cells, leading to persistent lung infections. Thus, the development of new therapeutic strategies to treat MDR biofilms-associated lung infections is crucial. Antimicrobial blue light (aBL) therapy, a subtype of photodynamic therapy, has shown potential antimicrobial activity. aBL uses a combination of blue light and endogenous photosensitizers to generate cytotoxic reactive oxygen species that inactivate bacteria through a multitarget mechanism, regardless of their antibiotic resistance profile. Thus, aBL can be considered as a promising strategy to treat lung infections.