Effect of topical ciprofloxacin 0.3% and ofloxacin 0.3% on the reduction of bacterial flora on the human conjunctiva

Abstract

Purpose: To evaluate quantitatively over time the reduction in bacterial flora on the human conjunctiva after treatment with topical ciprofloxacin 0.3% (Ciloxan) or topical ofloxacin 0.3% (Ocuflox).

Setting: Sinai Hospital of Baltimore, Baltimore, Maryland, USA.

Methods: Three study arms each consisted of 20 culture-positive eyes from patients 55 years or older. Pretreatment cultures were performed in all eyes. Eyes in the ciprofloxacin and ofloxacin arms received 1 antibiotic drop every 5 minutes for 3 doses. The conjunctiva of each treatment eye was recultured 15, 30, 60, and 120 minutes after application of the final antibiotic drop. Eyes in the control arm were recultured at corresponding time points. After 48 hours of incubation, colony counts were performed. Data were transformed into log units, and statistical analysis was performed. When compared to no treatment, instillation of ofloxacin 0.3% did not produce a significant reduction in bacterial colony forming units (CFUs) at 15, 30, or 60 minutes (P =.17). A marginally significant reduction was achieved 120 minutes after administration (P =.051).

Results: When compared to no treatment, instillation of ciprofloxacin 0.3% produced a significant reduction in bacterial CFUs at 15 minutes; this effect persisted for at least 2 hours (P <.0001). The reduction in bacterial CFUs by ciprofloxacin was significantly greater than that by ofloxacin at all measurements (P <.0001).

Conclusions: Ciprofloxacin 0.3% markedly reduced bacterial flora on the ocular surface within 15 minutes of instillation, and the effect lasted for at least 2 hours.