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Equine veterinary journal2024; 57(1); 38-46; doi: 10.1111/evj.14059

Equine ulcerative keratitis in the Netherlands (2012-2021): Bacterial and fungal isolates and antibiotic susceptibility.

Abstract: Ulcerative keratitis is a common ophthalmic disease in horses which can be complicated by microbial infection and requires immediate, accurate treatment to prevent loss of visual function or the eye. Objective: To report the results of microbial cultures, antibiotic susceptibility tests and corneal cytology in horses with ulcerative keratitis presented to a referral clinic, to assess agreement between cytology and culture results, to investigate whether previous topical treatment affected microbial culture results and whether the incidence of antimicrobial resistance changed during the study period. Methods: Retrospective analysis. Methods: Case characteristics and results of cytology and microbial cultures were retrieved. Statistical analyses included descriptive statistics, χ2 or Fisher's exact test and McNemar test. Results: Samples for bacterial culturing (n = 187), fungal culturing (n = 153) and cytology (n = 153) were collected from 178 horses. Bacterial and fungal cultures were positive in 36% (n = 67) and 20% (n = 30), respectively. Staphylococcus (n = 35/67; 48%), Streptococcus (n = 12/67; 16%) and Aspergillus species (n = 22/30; 81%) were most frequently found. Microorganisms were observed in 14% of cytology samples (n = 22/153). Acquired antibiotic resistance was commonly observed amongst Streptococcus and Staphylococcus species. Acquired antibiotic resistance to gentamicin was more common in cases previously treated with gentamicin (p < 0.001). The incidence of acquired antibiotic resistance did not increase significantly between Cohort 2012-2017 and Cohort 2018-2021. Neither bacterial nor fungal culturing results were in agreement with cytology findings (p < 0.001 and p = 0.02, respectively). In 6 of 104 samples that were negative on fungal culturing, cytology revealed fungal elements. Conclusions: Due to the retrospective nature of this study, some case characteristics and test results were unavailable. Conclusions: Acquired resistance was commonly observed amongst Streptococcus and Staphylococcus species, and in bacteria previously exposed to topical gentamicin. The incidence of acquired antibiotic resistance did not increase over time. When fungal cultures prove negative, cytology may have some added benefit in identifying keratomycosis.
© 2024 EVJ Ltd.
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Publication Date: 2024-01-14 PubMed ID: 38220439DOI: 10.1111/evj.14059Google Scholar: Lookup
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  • Journal Article

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.

This research article analyzes cases of ulcerative keratitis, a common ophthalmic disease in horses, to report microbiological culture results and antibiotic susceptibility tests. It also examines whether previous treatments affected culture results or if there were significant changes in antimicrobial resistance over a nine-year period.

Research Methodology

  • The study is a retrospective analysis where the researchers used past records to study the disease patterns.
  • Details about the cases, cytology results, and microbial culture results were collated from the referral clinic’s files.
  • Statistical analyses were performed to derive significant conclusions.
  • The researchers collected 187 samples for bacterial culturing, 153 for fungal culturing, and 153 for cytology from 178 horses.

Study Findings

  • Of the samples collected, bacterial cultures were positive in 36% of the cases and fungal cultures were positive in 20% cases.
  • The most common bacteria found were Staphylococcus (48%) and Streptococcus (16%) species while Aspergillus species (81%) topped the list in fungal cultures.
  • In 14% of the cytology samples, microorganisms were seen.
  • The study found that acquired antibiotic resistance, especially against gentamicin, was common in Streptococcus and Staphylococcus species.
  • Bacteria previously exposed to topical gentamicin also showed high antibiotic resistance.
  • Interestingly, the incidence of acquired antibiotic resistance did not show a significant increase over the studied time period (2012-2021).
  • The bacterial and fungal culture results were not in agreement with the cytology results – in 6 of 104 samples where fungal cultures were negative, cytology revealed fungal elements.

Conclusions

  • Due to the retrospective nature of the study, there were some limitations in terms of availability of case characteristics and test results.
  • Streptococcus and Staphylococcus species, and bacteria previously treated with gentamicin showed a trend of acquired resistance, however, the incidence of such resistance did not show a significant increase during the study period.
  • The study indicates that in cases where fungal cultures are negative, cytology could provide additional insights to identify keratomycosis (fungal infection of the cornea in horses).

Cite This Article

APA
Verdenius CY, Slenter IJM, Hermans H, Broens EM, Djajadiningrat-Laanen SC. (2024). Equine ulcerative keratitis in the Netherlands (2012-2021): Bacterial and fungal isolates and antibiotic susceptibility. Equine Vet J, 57(1), 38-46. https://doi.org/10.1111/evj.14059

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 57
Issue: 1
Pages: 38-46

Researcher Affiliations

Verdenius, Clara Y
  • Department of Clinical Sciences, Surgery of Companion Animals, Ophthalmology Section, Utrecht University, Faculty of Veterinary Medicine, Utrecht, The Netherlands.
Slenter, Inge J M
  • Department of Clinical Sciences, Surgery of Companion Animals, Ophthalmology Section, Utrecht University, Faculty of Veterinary Medicine, Utrecht, The Netherlands.
Hermans, Hanneke
  • Equine Eye Care, Utrecht, The Netherlands.
Broens, Els M
  • Department of Biomolecular Health Sciences, Infectious Diseases & Immunology, Utrecht University, Faculty of Veterinary Medicine, Utrecht, The Netherlands.
Djajadiningrat-Laanen, Sylvia C
  • Department of Clinical Sciences, Surgery of Companion Animals, Ophthalmology Section, Utrecht University, Faculty of Veterinary Medicine, Utrecht, The Netherlands.

MeSH Terms

  • Animals
  • Horses
  • Horse Diseases / microbiology
  • Horse Diseases / epidemiology
  • Horse Diseases / drug therapy
  • Corneal Ulcer / veterinary
  • Corneal Ulcer / microbiology
  • Corneal Ulcer / drug therapy
  • Corneal Ulcer / epidemiology
  • Retrospective Studies
  • Netherlands / epidemiology
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use
  • Male
  • Female
  • Bacteria / drug effects
  • Bacteria / isolation & purification
  • Fungi / drug effects
  • Fungi / isolation & purification
  • Eye Infections, Fungal / veterinary
  • Eye Infections, Fungal / microbiology
  • Eye Infections, Fungal / epidemiology
  • Eye Infections, Fungal / drug therapy
  • Drug Resistance, Bacterial
  • Drug Resistance, Fungal
  • Microbial Sensitivity Tests / veterinary
  • Eye Infections, Bacterial / veterinary
  • Eye Infections, Bacterial / microbiology
  • Eye Infections, Bacterial / epidemiology
  • Eye Infections, Bacterial / drug therapy

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Citations

This article has been cited 3 times.
  1. Stolle LM, Oltmanns H, Meißner J, Heun F, Schieder AK, Wolff HT, Ohnesorge B, Busse C. Polyhexanide, Povidone-Iodine, and Hypochlorous Acid Show High In Vitro Antimicrobial Efficacy Against Pathogens Commonly Associated With Equine Infectious Keratitis. Vet Ophthalmol 2026 Jan;29(1):e70141.
    doi: 10.1111/vop.70141pubmed: 41552904google scholar: lookup
  2. de Jong JE, Heuvelink AE, Dieste Pérez L, Holstege MMC. Aspergillus spp., aspergillosis and azole usage in animal species in Europe: Results from a multisectoral survey and review of recent literature. Med Mycol 2025 Jan 25;63(2).
    doi: 10.1093/mmy/myaf009pubmed: 39890594google scholar: lookup
  3. Roberts D, Thomas J, Salmon J, Cubeta MA, Stapelmann K, Gilger BC. Cold atmospheric plasma inactivates Aspergillus flavus and Fusarium keratoplasticum biofilms and conidia in vitro. J Med Microbiol 2024 Jul;73(7).
    doi: 10.1099/jmm.0.001858pubmed: 38985505google scholar: lookup
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