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BMC veterinary research2022; 18(1); 317; doi: 10.1186/s12917-022-03397-z

The bactericidal effect of two photoactivated chromophore for keratitis-corneal crosslinking protocols (standard vs. accelerated) on bacterial isolates associated with infectious keratitis in companion animals.

Abstract: Bacterial corneal infections are common and potentially blinding diseases in all species. As antibiotic resistance is a growing concern, alternative treatment methods are an important focus of research. Photoactivated chromophore for keratitis-corneal crosslinking (PACK-CXL) is a promising oxygen radical-mediated alternative to antibiotic treatment. The main goal of this study was to assess the anti-bactericidal efficacy on clinical bacterial isolates of the current standard and an accelerated PACK-CXL treatment protocol delivering the same energy dose (5.4 J/cm2). Methods: Clinical bacterial isolates from 11 dogs, five horses, one cat and one guinea pig were cultured, brought into suspension with 0.1% riboflavin and subsequently irradiated. Irradiation was performed with a 365 nm UVA light source for 30 min at 3mW/cm2 (standard protocol) or for 5 min at 18mW/cm2 (accelerated protocol), respectively. After treatment, the samples were cultured and colony forming units (CFU's) were counted and the weighted average mean of CFU's per μl was calculated. Results were statistically compared between treated and control samples using a linear mixed effects model. Results: Both PACK-CXL protocols demonstrated a significant bactericidal effect on all tested isolates when compared to untreated controls. No efficacy difference between the two PACK-CXL protocols was observed. Conclusions: The accelerated PACK-CXL protocol can be recommended for empirical use in the treatment of bacterial corneal infections in veterinary patients while awaiting culture results. This will facilitate immediate treatment, the delivery of higher fluence PACK-CXL treatment within a reasonable time, and minimize the required anesthetic time or even obviate the need for general anesthesia.
© 2022. The Author(s).
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Publication Date: 2022-08-17 PubMed ID: 35978428PubMed Central: PMC9386977DOI: 10.1186/s12917-022-03397-zGoogle Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research study investigates the effectiveness of two photoactivated chromophore for keratitis-corneal crosslinking (PACK-CXL) protocols in treating bacterial corneal infections in animals such as dogs, horses, and a guinea pig. It found that both PACK-CXL treatments significantly killed bacteria and there was no notable difference in efficiency between the two methods.

Research Methods

  • The researchers took clinical bacterial isolates from 11 dogs, five horses, one cat, and one guinea pig. These animals suffered from bacterial corneal infections – a common but potentially sight-threatening disease.
  • The isolated bacteria were then cultured and mixed with a 0.1% solution of riboflavin, a type of vitamin B2 commonly used in the PACK-CXL procedure as a photosensitizing agent.
  • The bacteria-riboflavin combination was then exposed to UV light at a wavelength of 365nm. Two different protocols were used: the standard protocol which involved 30 minutes of exposure at 3mW/cm, and the accelerated protocol which exposed the bacteria for 5 minutes at 18mW/cm. Despite the difference in exposure duration, both protocols delivered the same energy dose of 5.4 J/cm.
  • After exposure, the bacteria were cultured and assessed by counting the colony forming units (CFU’s) – a method for estimating the number of viable bacterial cells. The weighted average mean of CFU’s per μl was also calculated.
  • The results were then statistically compared against bacteria that were not exposed to the PACK-CXL treatment, providing a control sample for the experiment.

Research Findings

  • Both standard and accelerated PACK-CXL treatments significantly reduced the bacteria’s ability to grow and multiply compared to their untreated counterparts.
  • There was no statistically meaningful difference between the two PACK-CXL treatments, indicating them to be equally effective.

Conclusions

  • Given the results, the research suggests that the accelerated PACK-CXL protocol can be recommended for use in treating bacterial corneal infections in animals, allowing immediate treatment and potentially minimizing the amount of anesthetic time or removing the need for general anesthesia altogether.
  • The research also supports the idea that PACK-CXL could be a valid alternative to antibiotic treatments, particularly as antibiotic resistance becomes increasingly problematic.

Cite This Article

APA
Suter A, Schmitt S, Hübschke E, Kowalska M, Hartnack S, Pot S. (2022). The bactericidal effect of two photoactivated chromophore for keratitis-corneal crosslinking protocols (standard vs. accelerated) on bacterial isolates associated with infectious keratitis in companion animals. BMC Vet Res, 18(1), 317. https://doi.org/10.1186/s12917-022-03397-z

Publication

BMC veterinary research
ISSN: 1746-6148
NlmUniqueID: 101249759
Country: England
Language: English
Volume: 18
Issue: 1
Pages: 317

Researcher Affiliations

Suter, Anja
  • Ophthalmology Section, Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland. asuter@vetclinics.uzh.ch.
Schmitt, Sarah
  • Veterinary Bacteriology Section, Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Hübschke, Ella
  • Veterinary Bacteriology Section, Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Kowalska, Malwina
  • Epidemiology Section, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Hartnack, Sonja
  • Epidemiology Section, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Pot, Simon
  • Ophthalmology Section, Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.

MeSH Terms

  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use
  • Bacterial Infections / drug therapy
  • Bacterial Infections / veterinary
  • Collagen / therapeutic use
  • Cross-Linking Reagents / therapeutic use
  • Dog Diseases / drug therapy
  • Dogs
  • Eye Infections, Bacterial / drug therapy
  • Eye Infections, Bacterial / microbiology
  • Eye Infections, Bacterial / veterinary
  • Guinea Pigs
  • Horse Diseases / drug therapy
  • Horses
  • Keratitis / drug therapy
  • Keratitis / veterinary
  • Pets
  • Photosensitizing Agents / pharmacology
  • Photosensitizing Agents / therapeutic use
  • Riboflavin / pharmacology
  • Riboflavin / therapeutic use
  • Ultraviolet Rays

Conflict of Interest Statement

The authors declare that they have no competing interests.

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