Severe oral infection caused by Pseudomonas aeruginosa effectively treated with methylene blue-mediated photodynamic inactivation

•P. aeruginosa can provoke nosocomial infections with high morbidity and mortality.•Antibiotics resistance is commonly observed in P. aeruginosa infections.•Photodynamic inactivation can eradicate efficiently P. aeruginosa in oral infections refractory to antibiotics treatment. P. aeruginosa is a gram-negative bacterium present in nosocomial infections with high morbidity and mortality. This microorganism is frequently resistant to antibiotics, leading to clinical complications. In the present report, we described a clinical case of a patient with severe oral lesions caused by P. aeruginosa, which was refractory to antibiotics treatment and presented positive clinical outcomes after some sessions of antimicrobial photodynamic inactivation (API) mediated by methylene blue dye. We discuss the potential of API for P. aeruginosa refractory infections and possible resistance mechanisms of this microorganism to different API protocols.