Abstract
Objective: Evaluate methylene blue (MB) formulations containing oxygen carrier at different pHs in antimicrobial photodynamic therapy (aPDT). Material and Methods: Biofilms of Pseudomonas aeruginosa PA01 formed over acrylics specimens during five days were treated with aPDT using different formulations: MB/pH 7.4; MB/pH 5.6; MB/carrier pH 7.4; MB/carrier pH 5.6. Biofilms not exposed to treatment were used as a control. Blind examiner for the experimental groups performed the counting of colonies per ml suspension (CFU/ml). Two-way ANOVA was used to determine the effect of factors solvent (carrier vs water) and pH (7.4 vs 5.6). One-way ANOVA and post-hoc Tukey’s test was used to evaluate differences among the five groups (control; MB/carrier pH 7.4; MB pH 7.4; MB/carrier pH 5.6; MB pH 5.6). The Statistics 8.0 software was used (P<0.05). Results: All of photodynamic therapy groups showed significant reduction in P. aeruginosa compared to the control group. The solvent factor was not significant (P=0.18), while the pH factor presented statistical significance (P=0.01). When the carrier was used, MB formulation at pH 7.4 presented a statistically greater reduction of P. aeruginosa than the formulation with pH 5.6. Conclusion: The PDT using methylene blue formulations with oxygen carrier demonstrated potential for the treatment of localized infections by P. aeruginosa. MB formulations with oxygen carrier and pH 7.4 resulted in higher antimicrobial effect and should be considered for future studies with multispecies biofilms. KeywordsAntimicrobial photodynamic therapy; biofilm; laser; Pseudomonas aeruginosa.
Highlights
Antimicrobial photodynamic therapy has been proposed as an adjuvant to antibiotic treatment [1] with low probability of causing bacterial resistance [2], being effective against strains resistant to antibiotics [3]
Attempts to optimize the effect of Antimicrobial photodynamic therapy (aPDT) such as news photosensitizer (Ps), changes in the solvent of formulations [4,5], addition of oxygen carriers [4], nanoplatforms for the application of Ps [6,7], inhibitors of efflux pump [8,9], antibodies conjugated to Ps [10], have been investigated
When the oxygen carrier was used, the methylene blue (MB) formulation at pH 7.4 exhibited statistically significant reduction of P. aeruginosa compared to the formulation at pH 5.6
Summary
Antimicrobial photodynamic therapy (aPDT) has been proposed as an adjuvant to antibiotic treatment [1] with low probability of causing bacterial resistance [2], being effective against strains resistant to antibiotics [3]. The combination of Ps and light may not be sufficient for the effective eradication of biofilm [12]. The use of oxygen carriers could increase the availability of oxygen and facilitate the propagation of light during the irradiation, increasing the photochemical oxidation potential, facilitating the disruption of the biofilm matrix and the eradication of bacteria [12,14]. Kamuhabawa et al, in 2006, observed that the addition of perfluorecarene resulted in enhanced effect of photodynamic therapy with hypericin inducing increased apoptosis of tumor cell carcinoma [17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
