Predatory Bacteria can Reduce Induced Corneal Perforation and Proliferation in a Rabbit Keratitis Model.

Purpose: keratitis is a severe ocular infection that can lead to perforation of the cornea. In this study we evaluated the role of bacterial quorum sensing in generating corneal perforation and bacterial proliferation and tested whether co-injection of the predatory bacteria could alter the clinical outcome. with mutations were observed among keratitis isolates from a study collecting samples from India, so an isogenic mutant strain of was included.

Methods: Rabbit corneas were intracorneally infected with strain PA14 or an isogenic Δ mutant and co-injected with PBS or . After 24 h, eyes were evaluated for clinical signs of infection. Samples were analyzed by scanning electron microscopy, optical coherence tomography, sectioned for histology, and corneas were homogenized for CFU enumeration and for inflammatory cytokines.

Results: We observed that 54% of corneas infected by wild-type PA14 presented with a corneal perforation (n=24), whereas only 4% of PA14 infected corneas that were co-infected with perforate (n=25). Wild-type proliferation was reduced 7-fold in the predatory bacteria treated eyes. The Δ mutant was less able to proliferate compared to the wild-type, but was largely unaffected by .

Conclusion: These studies indicate a role for bacterial quorum sensing in the ability of to proliferate and cause perforation of the rabbit cornea. Additionally, this study suggests that predatory bacteria can reduce the virulence of in an ocular prophylaxis model.