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Topical levofloxacin 1.5% overcomes in vitro resistance in rabbit keratitis models
Author(s) -
Kowalski Regis P.,
Romanowski Eric G.,
Mah Francis S.,
Shanks Robert M. Q.,
Gordon Y. J.
Publication year - 2010
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2010.01897.x
Subject(s) - levofloxacin , ciprofloxacin , cefazolin , tobramycin , medicine , saline , ofloxacin , microbiology and biotechnology , keratitis , pharmacology , antibiotics , anesthesia , ophthalmology , biology , gentamicin
. Purpose: To determine whether topical levofloxacin 1.5% will successfully treat both levofloxacin‐resistant and susceptible Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA) in rabbit keratitis models. Methods: For levofloxacin‐resistant and susceptible SA, respectively, 32 New Zealand White (NZW) rabbits were intrastromally injected with 1000 colony‐forming units (CFU). After 4 hr, the corneas of eight rabbits were homogenized to determine onset CFU/ml. Twenty‐four rabbits were divided into three treatments: levofloxacin, vancomycin (cefazolin for levofloxacin‐susceptible SA) and saline. Twenty‐one drops were administered over 5 hr. One hour post‐treatment, the corneas were homogenized for CFU/ml. For levofloxacin‐resistant and susceptible PA, respectively, 32 NZW rabbits were intrastromally injected with 1000 CFU. After 16 hr, the corneas of eight rabbits were homogenized for CFU/ml. Twenty‐four rabbits were divided into three treatments: levofloxacin, tobramycin (ciprofloxacin for levofloxacin‐susceptible PA) and saline. Nineteen drops were administered over 8 hr. One hour post‐treatment, the corneas were homogenized for CFU/ml. The CFU/ml data were analysed for sterilization and non‐parametrically for reduction. Results: Levofloxacin 1.5% significantly reduced more (p < 0.05) levofloxacin‐resistant SA than vancomycin; was equivalent to cefazolin (p > 0.05) for levofloxacin‐susceptible SA; was equivalent to tobramycin for levofloxacin‐resistant PA; was equivalent to ciprofloxacin for levofloxacin‐susceptible PA; and significantly reduced more SA and PA than saline and onset. Levofloxacin 1.5% sterilized the corneas in the levofloxacin‐resistant and susceptible PA groups (32/32) and levofloxacin‐susceptible SA group (16/16), but not the levofloxacin‐resistant SA group (0/16). Conclusion: Levofloxacin 1.5% was effective for reducing SA and PA in the rabbit keratitis models regardless of in vitro resistance.