Effectiveness of ciprofloxacin-polystyrene sulfonate (PSS), ciprofloxacin and ofloxacin in a Staphylococcus keratitis model.
OBJECTIVE
Staphylococcus aureus causes severe corneal infections that often result in corneal scarring and blindness. Presently, therapy often involves the use of a fluoroquinolone antibiotic. This study, employing an experimental rabbit model of Staphylococcus keratitis, compared the effectiveness of two commonly prescribed formulations of fluoroquinolones to an experimental formulation, ciprofloxacin with polystyrene sulfonate (ciprofloxacin-PSS). The ciprofloxacin-PSS formulation uses an ion exchange resin to aid in the delivery of drug to the cornea.


METHODS
Early (4-9 h postinfection, PI) and late (10-15 h PI) therapies were studied, employing 5 groups: ciprofloxacin-PSS, ciprofloxacin, ofloxacin, PSS vehicle. and untreated. Dosing regimens were: every 30 min, 60 min, or a single drop applied at 9 h PI. Eyes were observed by slit lamp examination (SLE) and bacterial colony forming units (CFU) per cornea were determined.


RESULTS
Early phase therapy with ciprofloxacin-PSS, ciprofloxacin, or ofloxacin administered every 30 or 60 min were equally effective (P > or = 0.2880), decreasing CFU per cornea by >5 log. Ciprofloxacin was significantly more active than ciprofloxacin-PSS or ofloxacin (P < or = 0.0410) when applied as a single drop. Late therapy with ciprofloxacin-PSS, ciprofloxacin, or ofloxacin administered every 30 or 60 min resulted in >3 log decrease in CFU per cornea relative to controls (P < or = 0.0001).


CONCLUSIONS
Topical treatment of experimental Staphylococcus keratitis with ciprofloxacin-PSS, ciprofloxacin, or ofloxacin was effective. The effectiveness of ciprofloxacin-PSS suggests that improved drug delivery systems employing an ion exchange resin could be useful in an ocular fluoroquinolone formulation.
Department of Microbiology, Immunology, and Parasitology, LSU Medical Center, New Orleans, LA 70112-1393, USA.
J M
JM
Moreau
L C
LC
Green
L S
LS
Engel
J M
JM
Hill
R J
RJ
O'Callaghan
D000818:Animals; D000890:Anti-Infective Agents / Q000627:therapeutic use*; D002939:Ciprofloxacin / Q000031:analogs & derivatives / Q000627:therapeutic use*; D015169:Colony Count, Microbial; D003315:Cornea / Q000382:microbiology; D004195:Disease Models, Animal; D016503:Drug Delivery Systems; D015818:Eye Infections, Bacterial / Q000188:drug therapy* / Q000382:microbiology; D007634:Keratitis / Q000188:drug therapy* / Q000382:microbiology; D015242:Ofloxacin / Q000627:therapeutic use*; D009883:Ophthalmic Solutions; D011137:Polystyrenes / Q000627:therapeutic use*; D011817:Rabbits; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000254:growth & development
D000890:Anti-Infective Agents; D009883:Ophthalmic Solutions; D011137:Polystyrenes; D002939:Ciprofloxacin; C003321:polystyrene sulfonic acid; D015242:Ofloxacin