Janice Rodrigues Perussi
University of Sao Paulo, Brazil.
Title: Eradication of bacterial biofilms by photodynamic therapy
Biography
Biography: Janice Rodrigues Perussi
Abstract
Antimicrobial Photodynamic Therapy (A-PDT) is a promising alternative to fight local infections through the combination of a photosensitizer (PS), molecular oxygen and visible light producing reactive oxygen species (ROS) leading to microorganisms death. A-PDT was used to photoinactivate mono and multispecies biofilms of E. coli; E. faecalis and methicillin resistant S. aureus (MRSA) using multivariate analysis by Full Factorial Design 23 (FFD) and new chlorins: CHL-OH-A, CHL-PH-A and CHL-T synthesized in Brazil. Photodynamic treatment was performed using the FFD 23 incubated by 20, 30 and 40 min, PS concentrations of 5; 7.5 and 10 μmol L-1 and light doses of 15, 22 and 30 J cm-2 at 660 nm, subjecting the results to two-way ANOVA. Fluorescence and SEM were used to verify the membrane integrity and to confirm the photooxidation. Chlorins were effective for photoinactivation reducing above 3 logCFU mL-1 for all biofilm models. ROS photooxidize a wide variety of biomolecules, which was observed by Raman microspectroscopy (mRaman) besides the presence of characteristic carotenoid peaks (1550 and 1503 cm-1), which is an antioxidant pigment present in MRSA explaining a greater resistance in relation to E. faecalis, even though being gram-positive. FT-IV showed the photoxidation of the phospholipid membrane (1740 cm-1) of all bacteria after A-PDT. The highest reduction obtained was Δ7.4 logCFU mL-1 for E.faecalis, followed by 5.2; 4.5 and 3.6 for MRSA, multispecies and E. coli. A-PDI in combination with multivariate analysis and new chlorins presents potential to combat bacterial biofilms.