Experimental Pseudomonas aeruginosa Keratitis Associated with Soft Contact Lenses

Yang, H S; Hahn, Y HB; Lee, S J; Hur, B

Abstract

Pseudomonas aeruginosa keratitis is the most common corneal infection associated with soft contact lenses. We performed an experiment to investigate the pathogenesis of soft contact lens[SCL]-induced P. aeruginosa keratitis in soft contact lenses and rabbits. To develop the contamination of the SCL with P. aeruginosa, the lenses were incubated for 60 minutes with a suspension of 1 x 108 colony forming unit[CFU]/mL of P. aeruginosa. After 60 minutes, the SCLs were examined with scanning electron microscope. Then, sterile SCLs were placed on right eye of 10 rabbits under tarsorrhaphy for 7 days. The rabbits were divided into 4 groups[each 5 eyes]. In group 1, P. aeruginosa-conaminated SCLs were replaced on the cornea which had been placed with SCLs for 7 days. In group2, the eyes which had been placed with SCLs for 7 days were inoculated with 0.1mL of P. aeruginosa suspension. In group 3, P. aeruginosa-c onaminated SCLs were placed on normal cornea. In group 4, the normal eyes were inoculated with 0.1mL of P. aeruginosa suspension. After 48 hours, the corneas were resected for histopathologic examination. Scanning electron microscopic examination of P. aeruginosa-c ontaminated SCLs showed the adherence of P. aeruginosa on the SCL surface. The P. aeruginosa organisms and the SCLs are partly covered by biofilm. P. aeruginosa keratitis was developed in 5 eyes in group 1[5/5], 2 eyes in group 2[2/5], and 4 eyes in group 3[4/5]. But keratitis was not developed in group 4[0/5]. Scanning and transmission electron microscopic examination of ulcerated corneas showed intense infiltration of polymorphonuclear leukocytes[PMNs] in the area of ulceration and around P. aeruginosa organisms. In this study, it was found that the important factors in P. aeruginosa keratitis were a contaminated contact lens and a traumatic corneal epithelial defect.