Antimicrobial photodynamic therapy alone or in combination with antibiotic local administration against biofilms of Fusobacterium nucleatum and Porphyromonas gingivalis

• Published in: Journal of photochemistry and photobiology. B, Biology Vol. 188; pp. 135 - 145
• Main Authors: Tavares, Lívia J., de Avila, Erica D., Klein, Marlise I., Panariello, Beatriz H.D., Spolidório, Denise M.P., Pavarina, Ana Cláudia
• Format: Journal Article
• Language: English
• Published: Switzerland Elsevier B.V 01-11-2018; Elsevier BV
• Subjects: Anaerobic bacteria; Anaerobic conditions; Anti-Infective Agents - chemistry; Anti-Infective Agents - pharmacology; Antibiotics; Antiinfectives and antibacterials; Bacteria; Biofilms; Biofilms - drug effects; Biofilms - radiation effects; Combined modality therapy; Fusobacterium nucleatum; Fusobacterium nucleatum - isolation & purification; Fusobacterium nucleatum - physiology; Glucosamine - analogs & derivatives; Glucosamine - chemistry; Humans; Light; Light emitting diodes; Metronidazole; Metronidazole - pharmacology; Microbial Sensitivity Tests; Microbial Viability - drug effects; Minimum inhibitory concentration; Photodynamic therapy; Photosensitizing Agents - chemistry; Photosensitizing Agents - pharmacology; Polystyrene; Polystyrene resins; Porphyromonas gingivalis; Porphyromonas gingivalis - isolation & purification; Porphyromonas gingivalis - physiology; Reduction; Saliva - microbiology; Species; Viability; Anaerobic bacteria; Photodynamic therapy; Metronidazole; Combined modality therapy
• ISSN: 1011-1344; 1873-2682
• DOI: 10.1016/j.jphotobiol.2018.09.010

Antimicrobial photodynamic therapy (aPDT) kills several planktonic pathogens. However, the susceptibility of biofilm-derived anaerobic bacteria to aPDT is poorly characterized. Here, we evaluated the effect of Photodithazine (PDZ)-mediated aPDT on Fusobacterium nucleatum and Porphyromonas gingivalis biofilms. In addition, aPDT was tested with metronidazole (MTZ) to explore the potential antimicrobial effect of the treatment. The minimum inhibitory concentration (MIC) of MTZ was defined for each bacterial species. Single-species biofilms of each species were grown on polystyrene plates under anaerobic conditions for five days. aPDT was performed by applying PDZ at concentrations of 50, 75 and 100 mg/L, followed by exposure to 50 J/cm2 LED light (660 nm) with or without MTZ. aPDT exhibited a significant reduction in bacterial viability at a PDZ concentration of 100 mg/L, with 1.12 log10 and 2.66 log10 reductions for F. nucleatum and P. gingivalis in biofilms, respectively. However, the antimicrobial effect against F. nucleatum was achieved only when aPDT was combined with MTZ at 100× MIC. Regarding P. gingivalis, the combination of PDZ-mediated aPDT at 100 mg/L with MTZ 100× MIC resulted in a 5 log10 reduction in the bacterial population. The potential antimicrobial effects of aPDT in combination with MTZ for both single pathogenic biofilms were confirmed by live/dead staining. These results suggest that localized antibiotic administration may be an adjuvant to aPDT to control F. nucleatum and P. gingivalis biofilms.
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•F. nucleatum and P. gingivalis are involved in the progression of oral diseases.•PDZ-mediated aPDT reduces the number of bacteria within mature biofilms.•MTZ seems to make biofilm cells more sensitive to PDZ penetration.•Desired antimicrobial properties are achieved when MTZ is combined with PDZ-mediated aPDT.