Abstract
Abstract: :
Purpose: To evaluate the antimicrobial preservative efficacy of ZymarTM (gatifloxacin ophthalmic solution 0.3%, preserved with 0.005% benzalkonium chloride; BAK) and VigamoxTM (moxifloxacin ophthalmic solution 0.5%, not preserved) against several different species of yeast in conjunction with a 48–hour, in vitro zone inhibition assay. Methods: Candida albicans (4 strains), Candida guilliermondii (1), Candida kefyr (1), Candida parapsilosis (2), Candida tropicalis (2), Cryptococcus albidus (2), Cryptococcus neoformans (2), Geotrichum candium (1), Rhodotorula rubra (2), Torulopsis glabrata (2), and Yarrowia lipolytica (1) were grown on Sabouraud dextrose agar plates overnight at 30–35º C for 18–24 hours. Test organisms were transferred to Sabouraud dextrose plates creating a confluent lawn. Two pennicylinders were placed onto each inoculated plate. 0.3 mL of ZymarTM was added to one pennicylinder and 0.3 mL of VigamoxTM was added to the other for each plated strain. The plates were incubated for 48 hours at 30–35º C, and then zone sizes were measured in mm. A value of 0 mm was assigned if growth was observed inside the pennicylinder. Concurrently, test samples of ZymarTM and VigamoxTM were pooled and equal aliquots were inoculated with each test organism to contain approximately 1x105 to 1x106 colony forming units (CFU) per mL of test solution. The samples were neutralized and assayed at 4, 24, and 48 hours to determine the number of viable CFUs per mL of test solution. Results: ZymarTM produced greater zones of inhibition on all 20 plated strains compared with moxifloxacin ophthalmic solution. Growth was absent inside the pennicylinder on all plated strains treated with ZymarTM. In contrast, growth was visible inside the pennicylinders on 13 of the 20 plated yeast strains treated with VigamoxTM. Of note, for VigamoxTM, growth was observed on 3 of the 4 plated strains of Candida albicans and 5 of the 6 plated strains of the other Candida species. The preservative efficacy results of the plated samples demonstrated that the cidal activity of ZymarTM was very rapid. Eight of the ZymarTM test strains were reduced to levels of no recovery at 4 hours, while 16 of the VigamoxTM test strains remained at levels of 105 cells/mL. Conclusions: This 48–hour zone inhibition assay demonstrates that ZymarTM preserved with 0.005% BAK kills all strains of yeast tested to a greater extent than does VigamoxTM, which is unpreserved. This antifungal benefit has the potential for reducing fungal ocular infection during or after ophthalmic surgery and other patient usage.
Keywords: antibiotics/antifungals/antiparasitics