Experimental Study the role of LasA Protease of Pseudomonas aeruginosa in the Treatment of Bacterial Keratitis Caused by Staphylococcus aureaus

Abstract

Background: LasA protease play a major role in the colonization of the bacteria to the cornea during bacterial keratitis by preventing other bacteria from colonization to the cornea, for example in the mixed infection with S. aureus the enzyme eradicate the bacteria by their lysis it and finally eliminate the competitive for P. aeruginosa bacteria.Objective: To study the role of LasA protease of Pseudomonas aeruginosa in the treatment of experimental keratitis caused by S. aureus.Patients and methods: One hundred - twenty clinical samples (corneal scraping) were collected from patients suspected with bacterial keratitis presenting to Ibn Al-Haitham Teaching Hospital from May 2013 until November 2013. The bacterial isolate of P. aeruginosa that harbored LasA gene and capable of production of enzyme was analyzed by Real - time PCR. LasA protease enzyme was extracted by cold centrifugation and purified by gel - filtration chromatography.Results: The results of the experimental treatment of bacterial keratitis (in vivo) of infected rabbits eyes caused by S. aureus has showed that the efficacy of LasA protease was effective as Lysostaphin drug in eradicating the S.aureus from the infected corneas. While Vancomycin drug gave very little potency in the eradicating S. aureus from corneas in comparison with potency of LasA protease and Lysostaphin during this time but showed good potency with very late period ( approximately after 3 days) after application of treatment.Conclusion: The current study revealed that the LasA protease efficacy in the experimental treatment of bacterial keratitis of rabbit’s eye corneas was good and similar to that of Lysostaphin in eradicating S. aureus from corneas of these animals and was higher than that of Vancomycin.