Efficacy of topical gentamicin treatment after 193-nm photorefractive keratectomy in an experimental Pseudomonas keratitis model.
BACKGROUND
The treatment of Pseudomonas keratitis has many limitations, and further investigation to identify more effective approaches is required. We therefore studied the possible contribution of the debridement effect of 193-nm excimer laser on Pseudomonas keratitis in rabbit eyes.


METHODS
Pseudomonas keratitis was induced in 30 rabbit eyes by inflicting controlled central corneal scratches and applying a drop of Pseudomonas aeruginosa suspension. After 24 h, one cornea of each animal was photo-ablated (excimer laser: fluency 90 mJ/cm2, 10 Hz, 213 pulses), yielding 50 microns of tissue ablation, while the follow cornea served as control. Five groups of six animals each were formed and received: a subconjunctival injection of gentamicin 20 mg (group 1), topical 14 mg/ml gentamicin hourly (group 2) or every 2.5 h (group 3), or NaCl 0.9% hourly (group 4) for 8 h. In group 5, animals were sacrificed without additional treatment. After 9 h corneas were excised, homogenized, serially diluted, and plated on agar blood plates. The numbers of colony-forming units (CFU) per cornea were statistically evaluated (Mann-Whitney test).


RESULTS
In control eyes, a greater decrease of CFU was observed in group 2 than in group 3 (P = 0.03). In laser-ablated eyes, there was no difference in CFU between groups 2 and 3. Comparison of the excimer-treated and control eyes revealed a greater number of bacteria (CFU) in controls only in group 3 (P = 0.02).


CONCLUSIONS
Our study suggests that controlled debridement of cornea with excimer laser may improve the effect of topical antibiotics.
Department of Ophthalmology, Hadassah University Hospital, Jerusalem, Israel.
J
J
Frucht-Pery
G
G
Golan
I
I
Hemo
H
H
Zauberman
M
M
Shapiro
D000287:Administration, Topical; D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D015169:Colony Count, Microbial; D003315:Cornea / Q000187:drug effects / Q000382:microbiology / Q000601:surgery; D003646:Debridement; D004195:Disease Models, Animal; D015818:Eye Infections, Bacterial / Q000382:microbiology / Q000628:therapy*; D005839:Gentamicins / Q000627:therapeutic use*; D007267:Injections; D007634:Keratitis / Q000382:microbiology / Q000628:therapy*; D054018:Lasers, Excimer; D008297:Male; D009883:Ophthalmic Solutions; D018903:Photorefractive Keratectomy; D011182:Postoperative Care; D011552:Pseudomonas Infections / Q000382:microbiology / Q000628:therapy*; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D011817:Rabbits
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D009883:Ophthalmic Solutions