Reduction of endotracheal tube biofilms using antimicrobial photodynamic therapy

Background Ventilator-associated pneumonia (VAP) is reported to occur in 12-25% of patients who require mechanical ventilation with a mortality rate of 24-71%. The endotracheal tube (ETT) has long been recognized as a major factor in the development of VAP since biofilm harbored within the ETT become dislodged during mechanical ventilation and have direct access to the lungs. The objective of this study was to demonstrate the safety and effectiveness of a non-invasive antimicrobial photodynamic therapy (aPDT) treatment method of eradicating antibiotic resistant biofilms from ETT in an in vitro model. Methods Antibiotic resistant polymicrobial biofilms of Pseudomonas aerugenosa and MRSA were grown in ETT and treated, under standard ventilator conditions, with a methylene blue (MB) photosensitizer and 664 nm non-thermal activating light. Cultures of the lumen of the ETT were obtained before and after light treatment to determine efficacy of biofilm reduction. Results The in vitro ETT biofilm study demonstrated that aPDT reduced the ETT polymicrobial biofilm by >99.9% (P < 0.05%) after a single treatment. Conclusions MB aPDT can effectively treat polymicrobial antibiotic resistant biofilms in an ETT.