Journal of Bone and Joint Infection · Published 2025-12-09 · DOI 10.5194/jbji-10-561-2025
<p>Periprosthetic joint infections (PJIs), particularly those caused by multidrug-resistant organisms (MDROs), remain a major therapeutic challenge. Antimicrobial blue light (ABL) offers a promising non-antibiotic approach, inducing bacterial killing through photoexcitation of endogenous chromophores and subsequent reactive oxygen species generation. However, conventional single-point illumination systems are limited by uneven light distribution and poor penetration, restricting their use to superficial infections. We evaluated a novel isotropic optical fiber designed to overcome these geometric and optical constraints. The fiber was tested against vancomycin-resistant <i>Enterococcus faecium</i> (VR-Ef) and carbapenemase-producing <i>Klebsiella pneumoniae</i> (CP-Kp) in time-to-kill assays under low-power (20.1 mW mm<span class="inline-formula"><sup>−1</sup></span>) and high-power (40.3 mW mm<span class="inline-formula"><sup>−1</sup></span>) conditions over 60 min. Bacterial counts (CFU per mL) were determined at 0, 10, 20, 30, and 60 min. A one-way analysis of variance (ANOVA) with Tukey's post hoc test assessed time-dependent reductions; a two-way ANOVA evaluated the combined effects of illumination power and exposure time. ABL exposure resulted in time- and intensity-dependent bacterial reduction in both strains. Significant CFU reductions occurred from 30 min onward under high-power ABL (HP-ABL) and after 60 min under low-power ABL (LP-ABL) for both VR-Ef and CP-Kp (<span class="inline-formula"><i>p</i><0.001</span>). The two-way ANOVA revealed significant main and interaction effects of illumination power and exposure time (all <span class="inline-formula"><i>p</i><0.001</span>). Although bactericidal thresholds (<span class="inline-formula">≥3log <sub>10</sub></span> reduction) were not reached, bacterial killing increased markedly with higher power and longer exposure. This novel isotropic optical fiber enables uniform intraluminal ABL delivery, potentially extending blue-light therapy from superficial to deep surgical infections such as PJIs. Further optimization of illumination parameters and potential integration with photosensitizers may enhance its antimicrobial efficacy and clinical applicability.</p>
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