Effect of topical dexamethasone and ciprofloxacin on bacterial flora of healthy conjunctiva

Purpose To investigate the effects of topical dexamethasone and ciprofloxacin, alone and in combination, on the colony counts of conjunctival bacterial flora of healthy subjects. Methods A total of 100 healthy subjects were randomly divided into four groups, consisting of 25 subjects each. Group 1 was treated with dexamethasone phosphate 0.1% ( Maxidex). Group 2 was treated with ciprofloxacin 0.3% (Ciloxan) and Group 3 with a combination of these drugs. Group 4 received artificial tear solution ( Tears Naturale) and served as control. The drops were administered one drop every 1 min. A pretreatment culture and recultures at 30, 90, and 180 min after application of final drops were performed on all subjects. The bacterial growth was evaluated in a quantitative manner. All cultures were performed in a double-masked fashion. ANOVA test was used for statistical analyses. Results While there was no significant difference among mean number of pretreatment colonies between the groups ( P = 0.85); the differences at 30, 90, and 180 min were statistically significant ( P<0.001). During the study there was no statistically significant change in colony counts in Groups 1 and 4 ( P = 0.66 and 0.55, respectively). The colony count numbers decreased significantly at 30 and 90 min in Group 2 ( P<0.001 and P = 0.004) and at 30 min in Group 3 (P = 0.002). Conclusion Topically applied dexamethasone did not cause a significant change in colony counts of the healthy conjunctiva. Both ciprofloxacin and a combination of ciprofloxacin and dexamethasone were effective in the reduction of bacterial ocular flora.