Purchase this article with an account.
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.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
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.
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.
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.
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.
This PDF is available to Subscribers Only