Purpose: To compare efficacies of 1-day, 1-hour, and combined 1-day/1-hour preoperative topical gatifloxacin in eliminating conjunctival bacterial flora.
Design: Prospective, comparative case series.
Participants: Sixty patients (120 eyes) scheduled to undergo anterior segment intraocular surgery at Stanford University Medical Center.
Methods: Cultures were collected from the palpebral conjunctival sac at baseline and after 1 day (4 doses), 1 hour (3 doses), and 1 day/1 hour (7 doses) of gatifloxacin use.
Main outcome measures: Incidence of positive bacterial samples collected pre- and post-antibiotic treatment and number of colony forming units (CFUs).
Results: SeptiChek (Becton Dickinson, Franklin Lakes, NJ) positive cultures significantly decreased from 67% growth at baseline to 28% (P<0.0001) after 1 day and from 60% at baseline to 37% (P = 0.018) after 1 hour of gatifloxacin use. Reductions of 44% growth at baseline to 12% (P = 0.0001) after 1 day and 32% at baseline to 13% (P = 0.029) after 1 hour of gatifloxacin use were observed on blood agar. Surgical eyes that received both 1-day and 1-hour preoperative gatifloxacin had reductions from 67% growth at baseline to 18% posttreatment (P<0.0001) and 45% at baseline to 7% posttreatment (P<0.0001) on SeptiChek and blood agar media, respectively. In addition to a lower frequency of positive cultures, a significantly lower CFU count was found after 1-day (P = 0.004) and 1-hour (P = 0.049) gatifloxacin use compared with pretreatment levels. Combined 1-day/1-hour doses of gatifloxacin were associated with a greater reduction in CFUs (P = 0.001) when compared with 1-hour treatment alone.
Conclusions: Both 1-hour and 1-day topical gatifloxacin use are effective in reducing the frequency of conjunctival bacterial growth and the overall bacterial load as measured by CFUs, relative to baseline. Although a 1-hour pretreatment is associated with a reduction in bacterial growth, the combination of 1-day and 1-hour preoperative gatifloxacin dosing results in an even lower overall bacterial load, suggesting that the latter might be the preferred preoperative regimen for eyes undergoing anterior segment surgery.