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S. Schatz, H. Laubach, M. Clements; Viability of Candida Species in Ophthalmic Solutions of Fourth–Generation Fluoroquinolones . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3571.
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To evaluate the efficacy of gatifloxacin 0.3% ophthalmic solution (Zymar®; preserved with benzalkonium chloride 0.005%) and moxifloxacin 0.5% ophthalmic solution (Vigamox®; self–preserved) to resist contamination by strains of Candida, which are members of the normal human flora that can potentially cause ocular infections when present in large numbers or are able to penetrate susceptible host tissues.
Seven different clinical and environmental (ei) yeast strains_Candida albicans ei, C. albicans ATCC90028, C. krusei ei, C. krusei ATCC6258, C. parapsilosis ei, C. parapsilosis ATCC22019, and C. tropicalis ei., were tested for viability in the ophthalmic antibiotic solutions. 5 x 105 colony–forming units (CFU) of each strain in 0.5 mL phosphate–buffered saline (PBS) were added to 0.5 mL gatifloxacin 0.3% and moxifloxacin 0.5% ophthalmic solutions at time 0. Samples withdrawn after 0, 1, 2, 3, 24, and 48 hours at 30°C were diluted in PBS and analyzed for viable yeast by plating on Sabouraud's dextrose agar plates.
After 48 hours, the percent killing in gatifloxacin and moxifloxacin, respectively, was 96% and 6% for C. albicans ei, 100% and 61% for C. albicans ATCC90028, 100% and 0% for C. krusei ei, 100% and 28% for C. krusei ATCC6258, 98% and 0% for C. parapsilosis ei, 99% and 0% for C. parapsilosis ATCC22019, and 74% and 0% for C. tropicalis ei. The percent killing in the gatifloxacin 0.3% ophthalmic solution was greater than or equal to that in the moxifloxacin 0.5% ophthalmic solution at every time sample for every strain tested.
The formulation of Zymar® (gatifloxacin 0.3% ophthalmic solution) may provide protection against contamination of ophthalmic bottles by Candida species. This consideration is especially important for clinicians when treating a microbial keratitis and the offending microbial pathogens causing the keratitis are not known.
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