May 2006
Volume 47, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2006
Benzalkonium Chloride (BAK) Significantly Enhances the Antibacterial Efficacy of Gatifloxacin in the Staphylococcus Aureus NZW Rabbit Keratitis Model
Author Affiliations & Notes
  • F.S. Mah
    The Charles T. Campbell Laboratory, Ophthalmology and Visual Science Research Center, UPMC Eye Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • E.G. Romanowski
    The Charles T. Campbell Laboratory, Ophthalmology and Visual Science Research Center, UPMC Eye Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • R.P. Kowalski
    The Charles T. Campbell Laboratory, Ophthalmology and Visual Science Research Center, UPMC Eye Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • K.A. Yates
    The Charles T. Campbell Laboratory, Ophthalmology and Visual Science Research Center, UPMC Eye Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • Y.J. Gordon
    The Charles T. Campbell Laboratory, Ophthalmology and Visual Science Research Center, UPMC Eye Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • Footnotes
    Commercial Relationships  F.S. Mah, Allergan, F; Allergan, Alcon, C; E.G. Romanowski, Allergan, F; Allergan, Alcon, C; R.P. Kowalski, Allergan, F; Allergan, Alcon, C; K.A. Yates, None; Y.J. Gordon, Allergan, F; Allergan, Alcon, C.
  • Footnotes
    Support  Allergan Inc., NIH EY08227, NIH EY08098, RPB
Investigative Ophthalmology & Visual Science May 2006, Vol.47, 1905. doi:
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      F.S. Mah, E.G. Romanowski, R.P. Kowalski, K.A. Yates, Y.J. Gordon; Benzalkonium Chloride (BAK) Significantly Enhances the Antibacterial Efficacy of Gatifloxacin in the Staphylococcus Aureus NZW Rabbit Keratitis Model . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1905.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : To determine whether the preservative present in the commercial topical ophthalmic anti–infective agent ZYMAR®, 0.005% benzalkonium chloride (BAK), enhances the antibacterial efficacy of the active ingredient, 0.3% gatifloxacin, in the Staphylococcus aureus NZW rabbit keratitis model.

Methods: : 24 NZW rabbits were inoculated intrastromally in both eyes with approximately 3000 cfu of a gatifloxacin–resistant, methicillin–resistant S. aureus (MRSA) ocular isolate. The rabbits were randomly divided into 4 treatment groups of 6 rabbits each. Group I was treated with ZYMAR® (0.3% gatifloxacin + 0.005% BAK) (gatifloxacin ophthalmic solution 0.3%, Allergan Inc., Irvine CA). Group II was treated with 0.005% BAK (ZYMAR® vehicle without 0.3% gatifloxacin). Group III was treated with 0.3% gatifloxacin (0.3% gatifloxacin in complete vehicle but without 0.005% BAK). Group IV was treated with saline (Control). At 4 hours post–inoculation, topical treatment was initiated in both eyes every 15 minutes for 5 hours (21 total doses). One hour after therapy, the rabbits were euthanized and the corneas were homogenized to determine viable bacterial counts. The colony counts from both eyes were averaged, then were Log10 converted and analyzed using ANOVA.

Results: : Both ZYMAR® (2.3 ± 0.8 Log10 cfu/ml) and 0.3% gatifloxacin (3.8 ± 0.4 Log10 cfu/ml) demonstrated significantly fewer mean (± standard deviation) colony counts per cornea compared with 0.005% BAK (7.4 ± 0.2 Log10 cfu/ml) and the Control (7.5 ± 0.5 Log10 cfu/ml) (p=0.000, power = 1.0). Furthermore, ZYMAR® demonstrated significantly fewer mean colony counts per cornea compared with 0.3% gatifloxacin alone. There was no difference between 0.005% BAK and the Control.

Conclusions: : Both ZYMAR® (0.3% gatifloxacin + 0.005% BAK) and 0.3% gatifloxacin without 0.005% BAK were very effective in reducing the number of quinolone–resistant S. aureus in the NZW rabbit keratitis model with ZYMAR® being significantly more effective than 0.3% gatifloxacin without 0.005% BAK. 0.005% BAK alone demonstrated no decrease in the number of colony counts compared with the Control. In summary, 0.005% BAK significantly enhances the antibacterial efficacy of 0.3% gatifloxacin in the Staphylococcus aureus (MRSA) NZW rabbit keratitis model.

Keywords: keratitis • antibiotics/antifungals/antiparasitics • bacterial disease 
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