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Photo-activated porphyrin in combination with antibiotics: therapies against Staphylococci

Sana S Dastgheyb1, David M Eckmann, Russell J Composto

  • 1Department of Orthopaedic Surgery, Jefferson Medical College, 1015 Walnut St., Suite 501, Philadelphia, PA 19107, United States.

Journal of Photochemistry and Photobiology. B, Biology
|October 24, 2013
PubMed

Insights

Combining photodynamic therapy with antibiotics shows promise for treating resistant Staphylococcal infections. Photoactivated meso-tetra (4-aminophenyl) porphine (TAPP) enhances antibiotic effectiveness against bacteria like MRSA.

Area of Science:

  • Photomedicine
  • Antimicrobial Resistance
  • Bacteriology

Background:

  • Antibiotic resistance in Staphylococcal infections poses a significant therapeutic challenge.
  • Antimicrobial combination strategies, including photodynamic therapy (PDT), are being explored to overcome resistance.
  • Meso-tetra (4-aminophenyl) porphine (TAPP) is a cationic porphyrin investigated for its antimicrobial potential.

Purpose of the Study:

  • To investigate the combined efficacy of antibiotics and photoactivated TAPP against Staphylococcus aureus.
  • To evaluate the potential of PDT-antibiotic combinations in combating antibiotic-resistant bacterial strains.

Main Methods:

  • Characterization of the antimicrobial activity of photoactivated TAPP against Staphylococcus aureus.
  • Assessment of TAPP's activity in the presence of radical scavengers and its reactivation potential.
  • Evaluation of combination therapies using TAPP with various antibiotics (chloramphenicol, tobramycin, ceftriaxone, vancomycin) against S. aureus, MRSA, S. epidermidis, and E. coli.
  • Assessment of TAPP's phototoxicity on eukaryotic cells.

Main Results:

  • Photoactivated TAPP exhibits antimicrobial activity, which is reduced by radical scavengers but can be reactivated.
  • TAPP's antimicrobial effect is additive with chloramphenicol and tobramycin against S. aureus and E. coli.
  • Synergistic effects were observed with chloramphenicol and tobramycin against MRSA and S. epidermidis.
  • Ceftriaxone and vancomycin showed limited augmentation of TAPP's activity against S. aureus.
  • Illuminated TAPP demonstrated dose-dependent toxicity to eukaryotic cells.

Conclusions:

  • Sub-minimum inhibitory concentrations of photoactivated TAPP can enhance the efficacy of certain antibiotics against resistant bacteria.
  • PDT-antibiotic combinations offer a promising strategy to combat antibiotic resistance and extend the lifespan of existing antibiotics.
  • This approach may be particularly relevant for antibiotic-controlled release systems.
Keywords:
AntibioticsE. coliOsteoblastsPorphyrinsStaphylococciTAPP

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