Prophylactic gatifloxacin therapy in prevention of bacterial keratitis in a rabbit laser in situ keratomileusis model.
OBJECTIVE
Use the ID(50) (infectious dose to 50% of experimental animals) to quantify the most effective prophylactic dosing regimen to use with gatifloxacin 0.3% (Zymar) for the prevention of keratitis in a rabbit laser in situ keratomileusis model of Staphylococcus epidermidis infection.


METHODS
University Laboratory, University of Arizona, Tucson, Arizona, USA.


METHODS
Two groups of rabbits were compared in each of 2 experiments that were separated by 12 months. In the first experiment, rabbits receiving no postoperative antibiotic therapy (Group 1) were compared with rabbits receiving postoperative antibiotic therapy (Group 2). In the second experiment, postoperative antibiotic therapy (Group 3) was compared with preoperative and postoperative antibiotic therapy (Group 4). All antibiotic regimens used gatifloxacin 0.3%. Before antibiotic therapy began, corneal pockets were created in the right eye of each rabbit and all rabbits received balanced salt solution (BSS) only or BSS and S epidermidis inoculations in the corneal pocket. Rabbits were monitored for corneal infiltrates after surgery.


RESULTS
The ID(50) of the first, second, third, and fourth groups of rabbits was 10(2), 10(4), 10(5), and 10(7) organisms, respectively. The data showed a statistically significant difference between rabbits receiving BSS only and most rabbits receiving BSS plus inoculate at each postoperative measurement (P<.05).


CONCLUSIONS
The findings suggest that the use of both preoperative and postoperative antibiotic therapy may be most effective in preventing infection. Postoperative antibiotic therapy increased the number of S epidermidis necessary to cause infection by at least 100-fold over no antibiotic intervention. Preoperative plus postoperative antibiotic therapy increased the number of bacteria necessary to cause infection by at least 100-fold over postoperative therapy alone and by more than 10000-fold over no antibiotic intervention.
Slade
D Snow
DS
Department of Ophthalmology and Vision Sciences, University of Arizona, Tucson, Arizona, USA. snowslade@yahoo.com
Friday
Jason W
JW
Snyder
Robert W
RW
Nix
David E
DE
Kleinert
Leigh B
LB
Patula
Vangie B
VB
D000818:Animals; D000890:Anti-Infective Agents / Q000627:therapeutic use*; D019072:Antibiotic Prophylaxis; D015169:Colony Count, Microbial; D003320:Corneal Ulcer / Q000382:microbiology / Q000517:prevention & control*; D004195:Disease Models, Animal; D015818:Eye Infections, Bacterial / Q000382:microbiology / Q000517:prevention & control*; D024841:Fluoroquinolones / Q000627:therapeutic use*; D000077734:Gatifloxacin; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D011817:Rabbits; D013203:Staphylococcal Infections / Q000382:microbiology / Q000517:prevention & control*; D013212:Staphylococcus epidermidis / Q000254:growth & development*
D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D000077734:Gatifloxacin