The Effectiveness of Moxifloxacin for Gram-Negative Bacterial Keratitis

Abstract

Abstract: : Purpose: To determine the ability of topically applied moxifloxacin,a new fourth generation fluoroquinolone, to kill Pseudomonasor Serratia in the infected rabbit cornea.Methods: Log phaseP. aeruginosa strain 27853 or S. marcescens strain 93-1399-1were injected intrastromally (10³ colony forming units [CFU]in 10 µl) into rabbit corneas (N=6). From 16 to 22 hourspostinfection (PI), a single topical drop of moxifloxacin (0.5%),levofloxacin (0.5%, Quixin®), ofloxacin (0.3%, Ocuflox®)or ciprofloxacin (0.3%, Ciloxan®) was applied every 30 minutesfor 13 doses. At 23 hours PI, corneas were harvested, homogenizedand cultured quantitatively.Results: For Pseudomonas keratitis,the untreated eyes contained over 7 log CFU of bacteria. Allantibiotic treated eyes contained significantly fewer log CFUper cornea than the untreated eyes, and ofloxacin therapy wasless effective than the other antibiotic therapies (P≤0.01). 

For Serratia keratitis, untreated eyes contained almost 7 logCFU. The log CFU per cornea for all treated eyes were significantlylower than the untreated eyes, and eyes treated with moxifloxacinhad significantly fewer bacteria than eyes treated with theother antibiotics tested (P≤0.001).  

All four fluoroquinolones analyzed produced significant killingof Gram-negative bacteria in the rabbit cornea. Moxifloxacinwas the most effective of the four fluoroquinolones in eradicatingPseudomonas aeruginosa and Serratia marcescens in the rabbitkeratitis model.

Keywords: Pseudomonas • antibiotics/antifungals/antiparasitics • keratitis