Antimicrobial PDT effectively destroys E. coli and E. faecalis orthopaedic biofilms compared to low efficacy of a tobramycin and vancomycin mixture: an in vitro study using optical coherence tomography

Valentin Demidov; Matthew C. Bond; I. Leah Gitajn; Carey D. Nadell; Jonathan T. Elliott

doi:10.1117/12.2654683

14 March 2023 Antimicrobial PDT effectively destroys E. coli and E. faecalis orthopaedic biofilms compared to low efficacy of a tobramycin and vancomycin mixture: an in vitro study using optical coherence tomography

Valentin Demidov, Matthew C. Bond, I. Leah Gitajn, Carey D. Nadell, Jonathan T. Elliott

Author Affiliations +

Proceedings Volume 12358, Photonic Diagnosis, Monitoring, Prevention, and Treatment of Infections and Inflammatory Diseases 2023; 1235806 (2023) https://doi.org/10.1117/12.2654683
Event: SPIE BiOS, 2023, San Francisco, California, United States

Abstract

In orthopaedic trauma surgery, biofilms account for up to 65% of all infections, typically showing increased resistance to antibiotics, and thus novel anti-biofilm approaches need to be developed. Antimicrobial photodynamic therapy (PDT) had been recently proposed to combat clinically relevant biofilms using photosensitizers to kill bacteria with light-induced reactive oxygen species. In the first stage of the study reported here, we assessed the efficacy of this treatment type in eradication of biofilms typically present on surfaces of orthopaedic devices (e.g., intramedullary nails and osseointegrated prosthetic implants) by growing them in vitro inside soft lithography-fabricated microfluidic chips, treating them with 5- Aminolevulinic acid-based PDT and evaluating treatment efficacy with optical coherence tomography. PDT outcomes were compared to biofilm response to clinical antibiotic treatment (Vancomycin/Tobramycin 1:1 mixture). The antibacterial efficiency of 5-Aminolevulinic acid (5-ALA)-based PDT was found to be nonlinear dependent on the photosensitizer concentration and the light power density, with lowest parameters still being 17 times more effective than antibiotic-treated groups, reaching 99.98% bacteria kill at 250 mW/cm² light power density, 100 mg/mL 5-ALA concentration setting. Performed experiments enable the translation of the developed portable treatment/imaging platform to the second phase of the study: PDT treatment response assessment of biofilms naturally grown on orthopaedic devices of clinical patients.

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Valentin Demidov, Matthew C. Bond, I. Leah Gitajn, Carey D. Nadell, and Jonathan T. Elliott "Antimicrobial PDT effectively destroys E. coli and E. faecalis orthopaedic biofilms compared to low efficacy of a tobramycin and vancomycin mixture: an in vitro study using optical coherence tomography", Proc. SPIE 12358, Photonic Diagnosis, Monitoring, Prevention, and Treatment of Infections and Inflammatory Diseases 2023, 1235806 (14 March 2023); https://doi.org/10.1117/12.2654683

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