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2003 OMIG, Abstract 16

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The Antimicrobial Preservative Efficacy of ZymarTM and VigamoxTM Against Yeast Isolates
David Rupp, Teresa Reeves, Saroj Kapadia, Claude Anger
Microbiology Dept, Allergan, Inc.

Purpose: To evaluate the antimicrobial preservative efficacy of ZymarTM (gatifloxacin ophthalmic solution 0.3%) and VigamoxTM (moxifloxacin ophthalmic solution 0.5%) against a variety of yeast isolates in vitro.
Methods: Candida albicans (4 strains), Candida tropicalis (2), Candida parapsilosis (2), Cryptococcus neoformans (2), Cryptococcus albidus (2), Candida guilliermondii (1), Candida kefyr (1), Rhodotorula rubra (2), Yarrowia lipolytica (1) Geotrichum candiun (1) and Torulopsios glabrata (2) were grown at 30-35oC for 18-24 hours on Sabouraud dextrose agar. Test samples of commercially available gatifloxacin and moxifloxacin were pooled and equal aliquots of test sample were inoculated with each test organism to contain approximately 1 x 105 to 1 x 106 colony forming units (CFU) per mL of test solution. The samples were neutralized and assayed at 4, 24, 48 hrs and 7 days to determine the number of viable CFUs per mL of test solution.
Results: Overall moxifloxacin consistently allowed more fungal recovery than gatifloxacin at every time point and for every organism. For example, 11 of the moxifloxacin test strains were shown to remain at levels of 105 CFU/mL at 24 hours while l7 of the gatifloxacin samples were reduced to levels of no recovery. The cidal activity of gatifloxacin was shown to be very rapid. Eight of the gatifloxacin test strains were reduced to levels of no recovery at 4 hours, compared to 18 of the moxifloxacin test strains, which remained at levels of 105 cells/mL. Seven-day moxifloxacin data indicated that viable cells could still be recovered from 15 of the test strains, whereas all 20 of the gatifloxacin samples demonstrated no recovery.
Conclusions: ZymarTM, which is preserved with 0.005% benzalkonium chloride (BAK), effectively kills a variety of potentially pathogenic yeasts to a greater extent than does VigamoxTM, which contains no BAK. This added benefit can reduce the potential introduction of yeasts to the eye and surrounding structures during surgery and during patient usage.

Financial support: This study was supported by Allergan, Inc.

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