Peer-reviewed veterinary case report
New light treatment kills antibiotic-resistant bacteria in dog eye
By Furujo, Tomoya et al.·Published in Veterinary ophthalmology·2026·Joint Graduate School of Veterinary Sciences, Japan·View original on PubMed →
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Original publication title: In Vitro Efficacy Testing of TONS504-Based Photodynamic Antimicrobial Chemotherapy (TONS504-PACT) Under a 405-nm Light-Emitting Diode Against Antimicrobial-Resistant Bacteria Causing Canine Keratitis.
- Species:
- dog
Plain-English summary
Two dogs with eye infections caused by resistant bacteria were studied to see if a new treatment called TONS504-PACT, which uses a special light, could help. The treatment showed promising results against one type of bacteria, completely eliminating it, while it also reduced the presence of two other types significantly. However, TONS504 alone or just the blue light did not have any effect on the bacteria. This suggests that TONS504-PACT could be a potential option for treating tough eye infections in dogs, but more research is needed to confirm its safety and effectiveness in real-life situations.
People also search for: dog eye infection treatment · resistant bacteria in dogs · TONS504 for canine keratitis
Abstract
OBJECTIVE: To evaluate the in vitro efficacy of photodynamic antimicrobial chemotherapy (PACT) using TONS504, a newly developed hydrophilic and cationic photosensitizer, under a blue light emitting diode (LED) against antimicrobial-resistant bacteria isolated from dogs with keratitis. METHODS: Three bacterial strains (i.e., methicillin-resistant Staphylococcus pseudintermedius, extended-spectrum beta-lactamase-producing Escherichia coli, and Pseudomonas aeruginosa), isolated from two dogs with keratitis, were used in this study after antimicrobial susceptibility tests. PACT using TONS504 (0.1-100 mg/L) was performed under a 405-nm LED at 30 J/cm(20 mW/cm, 25 min) against bacterial suspensions (1.0 × 10CFU). Bacterial strains that were unexposed, exposed to TONS504 only, or exposed to blue light only served as controls. Antimicrobial effects were assessed by calculating the survival fraction based on the assessment of colony-forming units (CFU) on agar plates. RESULTS: Exposure to TONS504 or blue light only did not decrease the bacterial survival fraction against any of the strains. After TONS504-PACT under blue light against S. pseudintermedius, no colonies were observed at any TONS504 concentration, resulting in an approximate reduction of 2.3 × 10in the survival fraction. TONS504-PACT under blue light against E. coli and P. aeruginosa at 10 mg/L of TONS504 showed the greatest reduction in survival fraction, and the reduction was substantially lower than those of the respective controls. CONCLUSIONS: TONS504-PACT under blue light exhibited satisfactory activity against antimicrobial-resistant bacteria in vitro. Further research on the safety and clinical efficacy of TONS504-PACT under blue light is required; however, it is a potential treatment for antimicrobial-resistant bacterial keratitis in veterinary ophthalmology.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/40346765/