Benzalkonium chloride enhances the antibacterial efficacy of gatifloxacin in an experimental rabbit model of intrastromal keratitis.

Abstract

PURPOSE:

The aim of this study was to determine whether a preservative (0.005% benzalkonium chloride [BAK]) enhances the antibacterial efficacy of an antibiotic (0.3% gatifloxacin, [GAT]) in vivo.

METHODS:

Rabbits were inoculated intrastromally with GAT-resistant, methicillin-resistant Staphylococcus aureus or Staphylococcus epidermidis and then divided into four treatment groups: 0.3% GAT + 0.005% BAK; 0.3% GAT without BAK; vehicle including 0.005% BAK; and saline control. At 4 h postinoculation, topical treatment was initiated in both eyes every 15 min for 5 h. One (1) h after therapy, corneal colony counts were determined.

RESULTS:

For S. aureus, duplicate experiments demonstrated that GAT + BAK and GAT without BAK significantly reduced colony counts, compared with BAK or saline (P < 0.05). Further, GAT + BAK significantly reduced colony counts, compared with GAT without BAK. BAK alone was equivalent to the saline control. For S. epidermidis, duplicate experiments demonstrated that GAT + BAK and GAT without BAK significantly reduced colony counts, compared with BAK or saline (P < 0.05). There were no differences between GAT + BAK and GAT without BAK for S. epidermidis.

CONCLUSIONS:

For the first time, we demonstrated that a preservative (0.005% BAK) significantly enhanced the antibacterial efficacy of an antibiotic (0.3% GAT) in an experimental rabbit model of intrastromal keratitis.

• Authors: Eric G Romanowski, Francis S Mah, Regis P Kowalski, Kathleen A Yates, Y Jerold Gordon
• Journal: Journal of ocular pharmacology and therapeutics : the official journal of the Association for Ocular Pharmacology and Therapeutics (J Ocul Pharmacol Ther) Vol. 24 Issue 4 Pg. 380-4 (Aug 2008) ISSN: 1557-7732 [Electronic] United States
• PMID: 18665809 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• Benzalkonium Compounds
• Fluoroquinolones
• Gatifloxacin

Topics

• Animals
• Anti-Bacterial Agents (administration & dosage)
• Benzalkonium Compounds (administration & dosage)
• Corneal Stroma (drug effects, microbiology)
• Disease Models, Animal
• Drug Synergism
• Drug Therapy, Combination
• Eye Infections, Bacterial (drug therapy, microbiology)
• Female
• Fluoroquinolones (administration & dosage)
• Gatifloxacin
• Keratitis (drug therapy, microbiology)
• Rabbits
• Staphylococcal Infections (drug therapy, microbiology)