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Updated: May 19, 2026
Ex Vivo and In Vivo Animal Models for Mechanical and Chemical Injuries of Corneal Epithelium
Published on: April 6, 2022
Staphylococcus aureus infection of the rabbit cornea following topical administration
Aihua Tang1, Charles L Balzli, Armando R Caballero
1Department of Microbiology, University of Mississippi Medical Center, Jackson, MS 39216, USA.
Purpose:
To determine the ability of diverse S. aureus strains to infect the rabbit cornea following topical inoculation, with special emphasis on a strain of unusual virulence.
Materials And Methods:
S. aureus strains (5 × 10(5) colony forming units; CFU) were topically applied onto scarified rabbit corneas or 100 CFU were intrastromally injected into rabbit corneas. Eyes were scored by slit lamp examination (SLE) and corneas were cultured to determine the log CFU. Polymorphonuclear leukocytes (PMN) were quantified by myeloperoxidase assays and corneas underwent histopathological analysis. Hemolysin titers of S. aureus strains were determined and S. aureus interactions with rabbit tears or human corneal epithelial cells were investigated.
Results:
All strains injected into the cornea produced high SLE scores and multi-log increases in CFU. Following topical inoculation, four strains produced low SLE scores with no bacterial replication. One strain (UMCR1) topically infected the cornea, causing high SLE scores, extensive PMN infiltration, and multi-log increases in CFU. Histopathologic analysis demonstrated a PMN influx into the UMCR1-infected cornea, destruction of the corneal epithelium, and severe edema. Strain UMCR1 did not demonstrate a high hemolysin titer or resistance to the bactericidal activity of rabbit tears, but did invade human corneal epithelial cells with relatively high efficiency.
Conclusions:
One S. aureus strain demonstrated the ability to topically infect the rabbit cornea. This strain was previously found to be unique in its ability to infect the anterior chamber and conjunctiva, suggesting that a key mechanism may be employed to overcome the host defenses of these three ocular sites.
Insights
A unique Staphylococcus aureus strain (UMCR1) can topically infect the rabbit cornea, causing significant inflammation and damage. This finding is crucial for understanding ocular infections caused by virulent S. aureus strains.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Staphylococcus aureus is a common cause of bacterial keratitis.
- The mechanisms by which S. aureus infects the cornea, particularly virulent strains, are not fully understood.
Purpose of the Study:
- To evaluate the ability of different S. aureus strains to infect the rabbit cornea after topical application.
- To investigate a particularly virulent S. aureus strain (UMCR1) for its corneal infectivity.
Main Methods:
- Scarified rabbit corneas were inoculated topically or intrastromally with S. aureus strains.
- Corneal infection was assessed by slit lamp examination (SLE), bacterial culture (log CFU), and histopathology.
- Inflammation was quantified by polymorphonuclear leukocyte (PMN) assays.
- Hemolysin titers and interactions with tears/corneal cells were analyzed.
Main Results:
- Intrastromal injection of all strains led to severe keratitis.
- Topical inoculation with four strains resulted in no infection.
- Strain UMCR1 successfully infected the cornea topically, causing high SLE scores, extensive PMN infiltration, epithelial destruction, and edema.
- UMCR1 efficiently invaded human corneal epithelial cells but lacked high hemolysin titers or tear resistance.
Conclusions:
- A specific S. aureus strain (UMCR1) can cause topical infectious keratitis in rabbits.
- This strain's ability to infect the cornea, anterior chamber, and conjunctiva suggests a common mechanism for overcoming host defenses at these ocular sites.
