June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
Evaluation of in vivo murine modeling of Staphylococcus aureus bacterial keratitis
Author Affiliations & Notes
  • Tomas Meijome
    Ophthalmology and Visual Sciences, W K Kellogg Eye Center, Ann Arbor, Michigan, United States
  • Rachel Wozniak
    Ophthalmology, University of Rochester Medical Center, Rochester, New York, United States
  • Lyna Azzouz
    Ophthalmology and Visual Sciences, W K Kellogg Eye Center, Ann Arbor, Michigan, United States
  • Leslie M Niziol
    Ophthalmology and Visual Sciences, W K Kellogg Eye Center, Ann Arbor, Michigan, United States
  • Matthias Kriegel
    Ophthalmology and Visual Sciences, W K Kellogg Eye Center, Ann Arbor, Michigan, United States
  • Maria A Woodward
    Ophthalmology and Visual Sciences, W K Kellogg Eye Center, Ann Arbor, Michigan, United States
  • Footnotes
    Commercial Relationships   Tomas Meijome, None; Rachel Wozniak, None; Lyna Azzouz, None; Leslie Niziol, None; Matthias Kriegel, None; Maria Woodward, None
  • Footnotes
    Support  NIH Grant R01EY031033
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 904. doi:
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      Tomas Meijome, Rachel Wozniak, Lyna Azzouz, Leslie M Niziol, Matthias Kriegel, Maria A Woodward; Evaluation of in vivo murine modeling of Staphylococcus aureus bacterial keratitis. Invest. Ophthalmol. Vis. Sci. 2021;62(8):904.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Staphylococcus aureus, a predominant pathogen in bacterial keratitis (BK), is a significant contributor to worldwide disease burden of corneal vision loss and blindness. Validated animal models have historically played a critical role in the study of BK; however, a direct correlation to human disease has yet to be thoroughly established. We propose to advance our understanding of an established murine model of BK by correlating advanced image analysis, disease severity, and bacterial burden.

Methods : Twenty BALB/c strain mice underwent three parallel scratches of the left corneal epithelium and anterior stroma with subsequent inoculation of 5x106 S. aureus cells (50ml of 108 S. aureus cells/ml). At 48 hours post-infection, subjective clinical disease severity was graded based on an established scale from 0 (no clinically evident disease) to 4 (corneal perforation). Slit-lamp photography and image annotation with ImageJ were used to measure stromal infiltrate area (mm2). Eyes were homogenized, and the bacterial load (colony forming units or CFU) was determined. Pearson and Spearman correlations were used to estimate the linear association between severity grade, ulcer size and CFUs.

Results : The average ulcer size was 1.3 mm2 (SD = 0.9) and 50% were identified as grade 2 clinical severity (0: 5%, 1: 10%,2: 50%, 3: 25%, 4: 10%). Bacterial burden was evaluated in twenty mice with mean of 8 x 105 CFU/ml (SD = 1.4 x 105 CFU/ml). A strong linear association was found between bacterial burden (CFUs) and stromal infiltrate measurements (Pearson correlation = 0.72, p = 0.0026,) and between CFUs and severity grade (Spearman correlation = 0.79, p = 0.0005). No significant correlation was found between severity grade and stromal infiltrate measurements (p = 0.17).

Conclusions : Clinical severity and corneal infiltrate size were both strongly correlated with the bacterial corneal load, suggesting that both clinical grading and image annotation approaches have potential to estimate disease severity in this murine model of BK. Further research in animal models will be important in developing risk stratification models and standardized treatment methods for human disease.

This is a 2021 ARVO Annual Meeting abstract.

 

Representative external photograph of murine bacterial keratitis model (A) with corresponding quantitative image analysis (B).

Representative external photograph of murine bacterial keratitis model (A) with corresponding quantitative image analysis (B).

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