Curcumin-mediated photoinactivation of multispecies biofilms

Objectives: This study evaluated the effect of antimicrobial Photodynamic Therapy (aPDT) mediated by Curcumin (CUR) and blue LED light against multi-species biofilms of Candida albicans (Ca), Streptococcus mutans (Sm) and methicillin-resistant Staphylococcus aureus (MRSA).
Methods: Standardized suspensions (10⁶-10⁷ CFU/ml (mid-log phase)) of Ca (ATCC 90028), Sm (UA159 ATCC700610) and MRSA (ATCC 33591) were transferred to 96-well culture plates, which were incubated in 5% CO₂ incubator for 90min at 37°C (adhesion phase). Then, the samples were washed with PBS and incubated with BHI medium at 37°C in 5% CO₂. After 48h, biofilms were washed and subjected to aPDT by incubation with CUR (1200μM) for 40min followed by irradiation for 40min with LED light (455nm; 57.6 J/cm²). Additional samples were treated only with LED or CUR, while the control group received no treatment (n = 9). Afterwards, the biofilm was disrupted and aliquots of each sample were transferred to specific culture mediums and incubated for 48h for colonies quantification. Values of log₁₀(CFU/mL) were analyzed by ANOVA/Welch and Tukey/Games-Howell tests (α=0.05).
Results: The aPDT group showed a significant reduction (ρ <0.05) than the other groups which did not differ (ρ> 0.05) among them. For Ca, Sm and MRSA, the reduction compared to control group was 3.04, 2.54 and 1.57 log₁₀, respectively.
Conclusions: CUR-mediated aPDT reduced viability of the multispecies biofilm.