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2018 Agenda and Abstracts | < Previous Next >

2018 OMIG Abstract

In Vitro Synergy Testing Of Commonly Used Anti-Amoebic Agents:
Antagonism Of Voriconazole


Jeremy D Keenan, MD, MPH1,2, Maya Talbott, BS1, Vicky Cevallos, MT1,2, Michael C Chen2,
Stephanie A Chin2, Lalitha Prajna3, Gerami D Seitzman, MD1,2, Thomas M Lietman, MD1,2
1F.I. Proctor Foundation, San Francisco, CA, USA; 2Department of Ophthalmology, San Francisco, CA, USA; 3Aravind Eye Care System, Madurai, India

 

Purpose: Most ophthalmologists prescribe more than one anti-amoebic medication for Acanthamoeba keratitis, with a primary rationale being the potential for drug synergy. However, few studies have assessed the efficacy of combination anti-amoebic drug therapy. In this study, synergy testing was performed for the most commonly used anti-amoebic agents.

Methods: Synergy testing for all combinations of chlorhexidine, propamidine, and voriconazole was performed with a microdilution checkerboard assayon 10 clinical acanthamoeba isolates collected at the Proctor Foundation from 2008-2012.

Results: Chlorhexidine and propamidine were cysticidal, with median minimum cysticidal concentrations (MCCs) of 12.5 (range 1.5 to 50) and 11.7 (range 0.2 to 250), respectively. Voriconazole was not cysticidal, with a median MCC of >10,000 g/mL. The combination of chlorhexidine and propamidine did not markedly change the cysticidal activity compared to either drug alone. In contrast, voriconazole antagonized the cysticidal activity of both chlorhexidine and propamidine.

Conclusion: In an in-vitro assay, voriconazole reduced the cysticidal activity of the most commonly used anti-amoebic drugs.While the in vivo drug interactions could be different, these observations may be useful in cases of non-healing acanthamoeba keratitis being treated with combination therapies including voriconazole.

Disclosure: N

Support: Research to Prevent Blindness, That Man May See

 

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