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Updated: May 2, 2026
Intravitreal Injection and Quantitation of Infection Parameters in a Mouse Model of Bacterial Endophthalmitis
Published on: February 6, 2021
Pathogenicity of ocular isolates of Acinetobacter baumannii in a mouse model of bacterial endophthalmitis
Deepa Talreja1, Keith S Kaye, Fu-shin Yu
1Kresge Eye Institute, Wayne State University, Detroit, Michigan, United States.
Purpose:
To determine the virulence properties of ocular isolates of Acinetobacter baumannii in causing endophthalmitis in a mouse model.
Methods:
Endophthalmitis was induced by intravitreal injections of the bacteria into C57BL/6 (B6) mouse eyes. The disease progression was monitored by ophthalmoscopic, electroretinography (ERG), histologic, cell death (TUNEL labeling), and microbiological parameters. The expression of cytokines/chemokines was checked by quantitative RT-PCR (qRT-PCR) and ELISA. Flow cytometry was used to determine cellular infiltration. The role of neutrophils was determined using neutropenic mice. The virulence traits (biofilm formation, adherence, and cytotoxicity) of the ocular isolates were tested using corneal epithelial cells.
Results:
Among the three clinical isolates and a standard ATCC 19606 strain tested, a biofilm producing multidrug resistant (MDR) strain of A. baumannii AB12 caused severe endophthalmitis (100% destruction of the eyes) leading to the loss of retinal function as assessed by ERG analysis. Elevated levels of inflammatory mediators (TNF-α, IL-1β, CXCL2, and IL-6) were detected in AB12-infected eyes. Histologic and TUNEL staining revealed increased retinal cell death and the flow cytometry data showed the presence of inflammatory cells, primarily neutrophils (CD45(+)/Ly6G(+)). Neutropenic mice showed an increased bacterial burden, reduced inflammatory response, and severe tissue destruction.
Conclusions:
These results indicate that A. baumannii causes severe intraocular inflammation and retinal damage. Furthermore, neutrophils play an important role in the pathogenesis of A. baumannii endophthalmitis.
Insights
Acinetobacter baumannii causes severe endophthalmitis and retinal damage in mice. Neutrophils are crucial in the pathogenesis of this ocular infection, highlighting their role in bacterial endophthalmitis.
Area of Science:
- Ophthalmology
- Microbiology
- Immunology
Background:
- Acinetobacter baumannii is an opportunistic pathogen.
- Ocular infections with A. baumannii can lead to severe vision impairment.
Purpose of the Study:
- To investigate the virulence of ocular Acinetobacter baumannii isolates.
- To determine the role of neutrophils in A. baumannii-induced endophthalmitis.
Main Methods:
- Endophthalmitis was induced in a mouse model using A. baumannii.
- Disease progression was assessed via ophthalmoscopy, electroretinography, histology, and microbiology.
- Cytokine expression, cellular infiltration, and neutrophil depletion were analyzed.
Main Results:
- A multidrug-resistant A. baumannii strain caused severe endophthalmitis and retinal dysfunction.
- Elevated inflammatory mediators and neutrophil infiltration were observed in infected eyes.
- Neutropenic mice exhibited increased bacterial burden and tissue destruction.
Conclusions:
- A. baumannii causes significant intraocular inflammation and retinal damage.
- Neutrophils play a critical role in the pathogenesis of A. baumannii endophthalmitis.
