Prospective randomized study determining whether a 3-day application of ofloxacin results in the selection of...

To determine whether a 3-day application of ofloxacin results in the selection of fluoroquinolone-resistant conjunctival coagulase-negative Staphylococcus.

Prospective randomized trial.

Patients scheduled for ocular surgery were randomized to a control (89 eyes) or study group (70 eyes). The study group received topical ofloxacin (0.3%) four times a day for 3 days. Conjunctival cultures were obtained at baseline (T0) and after 3 days of ofloxacin (T1). Cultures were also obtained at T0 and T1 for the control group, but these eyes did not receive an an-tibiotic. Bacteria isolated were identified and antibiotic susceptibility was determined.

At T0, 53 out of 89 patients (60%) in the control and 48 out of 70 patients (69%) in the study group harbored coagulase-negative Staphylococcus. Among these coagulase-negative Staphylococcus, 12 out of 53 in the control and 11 out of 48 in the study group were resistant to ofloxacin (p>0.9999). At T1, significantly fewer coagulase-negative Staphylococcus (p=0.0003) were isolated from the study group (18 coagulase-negative Staphylococcus), compared the control group (48 coagulase-negative Staphylococcus). Of these, 5 out of 17 coag-ulase-negative Staphylococcus in the study group and 9 out of 48 coagulase-negative Staphylococcus in the control group were resistant to ofloxacin (p=0.5649). There was no significant difference in the number of coagulase-negative Staphylococcus resistant to ciprofloxacin or norfloxacin in the study group compared to the control group at T1.

Ofloxacin given four times a day for 3 days does not select out for conjunctival fluoroquinolone-resistant coagulase-negative Staphylococcus.