Optimization of Antimicrobial Photodynamic Therapy in Biofilms by Inhibiting Efflux Pump

Author(s)

Fogaca de Aguiar Coletti, Tatiana Maria Starck ; de Freitas, Laura Marise ; Fusco Almeida, Ana Marisa ; Fontana, Carla Raquel

• Document type: Journal article
• Source: Photomedicine and Laser Surgery; v. 35, n. 7, p. 378-385, JUL 2017.
• Web of Science Citations: 5

Abstract

Background: One of the main mechanisms of microbial resistance is given by efflux pumps, which reduce the effectiveness of antimicrobials by decreasing their intracellular concentration. Objective and methods: Considering that efflux pump inhibitors are promising adjuvant molecules for antibiotics in infections, in this study, using XTT test and colony forming unit (CFU) counting, we evaluated the association between the pump inhibitor verapamil (VP) and the antimicrobial photodynamic therapy (aPDT) mediated by methylene blue (MB) in biofilms of Escherichia coli and Staphylococcus aureus to optimize the bacterial reduction. Results: By applying 44J/cm(2), 215g/mL of VP, and 200g/mL of MB, we obtained 80% of metabolism reduction and 3.4 log(10) CFU/mL decrease for E. coli. Biofilm of S. aureus presented 80% of metabolism reduction and 3.65 log(10) CFU/mL decrease when 22J/cm(2), 312g/mL of VP, and 200g/mL of MB was used. Applying 200g/mL of MB, the E. coli biofilm required a higher dose of light, while the S. aureus biofilm required a higher concentration of VP to obtain the same reduction. Conclusions: The VP optimized the efficiency of aPDT and showed no toxicity when used alone in both strains, proving that inhibiting efflux pumps in combination with aPDT has great potential for clinical application. (AU)

• FAPESP's process: 16/05345-4 - Improving antimicrobial photodynamic therapy for infectious disease associating peptide aurein 1.2
• Grantee: Carla Raquel Fontana Mendonça
• Support type: Regular Research Grants