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Listeria monocytogenes keratitis
G W Zaidman1, P Coudron, J Piros
1Department of Ophthalmology, Westchester County Medical Center, New York Medical College, Valhalla 10595.
Abstract:
We treated a farmer who had Listeria monocytogenes bacterial keratitis. Therapy with topical antibiotics was unsuccessful; it was necessary to treat the patient with topical and systemic penicillin and gentamicin. To elucidate the pathogenesis of this infection, we developed a rabbit model. Using the patient's strain of L. monocytogenes, we determined that the severity of the rabbit infection was dose-related. If we used an inoculum of more than 10(7) organisms, many of the features of the human Listeria keratitis were mimicked. We also found that treatment with either penicillin or gentamicin did not control the infection as well as using both antibiotics simultaneously, a combination which resulted in relatively rapid resolution of infection and no corneal scarring. The human and animal data indicate that L. monocytogenes can be a virulent corneal pathogen. Listeria corneal infections must be treated aggressively with both penicillin and gentamicin to prevent permanent visual loss.
Insights
Listeria monocytogenes can cause severe bacterial keratitis. Aggressive treatment with both penicillin and gentamicin is crucial to prevent vision loss from this virulent corneal pathogen.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Listeria monocytogenes is a bacterium that can cause serious infections.
- Bacterial keratitis, an infection of the cornea, can lead to vision impairment.
Observation:
- A farmer developed Listeria monocytogenes bacterial keratitis unresponsive to topical antibiotics.
- A rabbit model was developed to study the pathogenesis of Listeria keratitis.
- Infection severity in rabbits was dose-dependent, mimicking human symptoms at high inoculums.
Findings:
- Combined topical and systemic penicillin and gentamicin effectively treated Listeria keratitis.
- Monotherapy with penicillin or gentamicin was less effective than combination therapy.
- Combination therapy led to rapid infection resolution and prevented corneal scarring.
Implications:
- Listeria monocytogenes is a virulent corneal pathogen requiring prompt and aggressive treatment.
- Combined penicillin and gentamicin therapy is recommended for Listeria keratitis.
- Early and effective treatment can prevent permanent visual loss from Listeria infections.