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Updated: Jun 4, 2026
An In Vitro Model to Study the Effect of 5-Aminolevulinic Acid-mediated Photodynamic Therapy on Staphylococcus aureus Biofilm
Published on: April 16, 2018
Effect of photodynamic therapy on clinical isolates of Staphylococcus spp
Michelle Miyabe1, Juliana Campos Junqueira, Anna Carolina Borges Pereira da Costa
1Department of Biosciences and Oral Diagnosis, School of Dentistry of São José dos Campos, UNESP, São José dos Campos, SP, Brazil.
Abstract:
Staphylococcus spp. are opportunistic microorganisms known for their capacity to develop resistance against antimicrobial agents. The objective of this study was to evaluate the effect of photodynamic therapy (PDT) on 20 Staphylococcus strains isolated from the human oral cavity, including S. aureus, S. schleiferi, S. epidermidis, S. capitis, S. haemolyticus, and S. lentus. A suspension of each Staphylococcus strain (10(6) cells/mL) was submitted to PDT using methylene blue and a low power laser. The isolated effects of methylene blue, laser treatment and ciprofloxacin were also evaluated. After the experimental treatments, 0.1 mL aliquots of the suspensions were seeded onto BHI agar for determination of the number of colony-forming units (CFU/mL). The results were analyzed by analysis of variance and Tukey's test (p < 0.05). The mean reduction in bacterial counts of the strains submitted to PDT ranged from 4.89 to 6.83 CFU (log10)/mL, with the observation of a decreasing susceptibility to treatment of S. schleiferi, S. haemolyticus, S. epidermidis, S. capitis, S. aureus, and S. lentus. The results showed that PDT was effective in reducing the number of viable cells of all clinical Staphylococcus isolates studied.
Insights
Photodynamic therapy (PDT) effectively reduced viable Staphylococcus bacteria from the oral cavity. This antimicrobial approach shows promise against various Staphylococcus species, including S. aureus, highlighting its potential in combating resistant strains.
Area of Science:
- Microbiology
- Photodynamic Therapy
- Antimicrobial Resistance
Background:
- Staphylococcus species are opportunistic pathogens frequently developing antimicrobial resistance.
- Oral cavity harbors diverse Staphylococcus strains, posing potential health risks.
- Photodynamic therapy (PDT) offers a potential alternative to conventional antibiotics.
Purpose of the Study:
- To investigate the efficacy of photodynamic therapy (PDT) against Staphylococcus strains from the human oral cavity.
- To evaluate PDT's impact on 20 clinical isolates including S. aureus, S. schleiferi, S. epidermidis, S. capitis, S. haemolyticus, and S. lentus.
Main Methods:
- Bacterial suspensions (10^6 cells/mL) of Staphylococcus strains were treated with methylene blue and a low-power laser.
- Isolated effects of methylene blue, laser, and ciprofloxacin were assessed.
- Colony-forming units (CFU/mL) were determined post-treatment using BHI agar and analyzed statistically.
Main Results:
- PDT significantly reduced bacterial counts, with mean reductions ranging from 4.89 to 6.83 log10 CFU/mL.
- Susceptibility to PDT varied among species, with S. schleiferi, S. haemolyticus, and S. epidermidis showing decreased susceptibility.
- All tested Staphylococcus isolates demonstrated reduced viability following PDT treatment.
Conclusions:
- Photodynamic therapy is an effective method for reducing viable Staphylococcus cells in clinical isolates from the oral cavity.
- PDT presents a viable alternative for managing Staphylococcus infections, particularly in the context of rising antimicrobial resistance.
- Further research into optimizing PDT protocols for specific Staphylococcus species is warranted.
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