Antimicrobial effect of blue light on antibiotic-sensitive and drug-resistant Escherichia coli: a novel isotropic optical fiber

Background Orthopaedic oncological pelvic reconstructions have an elevated risk of infection with gram-negative bacteria. This study evaluates the bactericidal ability of a novel antimicrobial blue-light (ABL)-emitting optical fiber on antibiotic-sensitive Escherichia coli (AS-Ec) and ESBL-producing E. coli (ESBL-Ec).

Time-to-kill assays used a 10 mL NaCl solution with a starting inoculum of 1x105 CFU/mL for AS-Ec or ESBL-Ec. Assays were repeated at least eight times per strain. Experimental tubes had either one optical fiber [20.1 mW/mm; low power (LP)] or two optical fibers [40.3 mW/mm, high power (HP)], which delivered five wavelengths of ABL over 60 min. Control tubes had no optical fibers. Fifty microliter samples were taken from each tube at 0, 10, 20, 30, and 60 min, streaked onto agar plates, and incubated. CFU/mL were determined. Bactericidal reduction was defined as ≥99.9% (≥3log10) reduction in CFU/mL. One-way ANOVA was conducted.

Bactericidal effects were seen for AS-Ec under both LP-ABL and HP-ABL with a log10CFU/mL±SD difference of 3.44±0.35 (p<0.0001) and 3.74±0.21 (p<0.0001) at 30 and 20 min, respectively. For ESBL-Ec, while there was a significant reduction in bacterial colony formation, the bactericidal threshold was not reached with a log10CFU/mL±SD difference of only 1.02 ±0.41 (p<0.0001) and 2.53±0.22 (p<0.0001) at 60 min for LP-ABL and HP-ABL, respectively.

A novel ABL-emitting optical fiber exhibited bactericidal effects in AS-Ec and a clinically meaningful reduction in ESBL-Ec, providing a promising avenue for the use of ABL as a potential therapy for gram-negative infections. - Received: - Version Posted: