In Vitro susceptibility of ocular bacterial flora taken preoperatively to four fluoroquinolones

摘要

Objective: The purpose of this study was to determine the normal ocular bacterial flora isolated from patients undergoing cataract surgery and to evaluate their in vitro susceptibility to ofloxacin, ciprofloxacin, lomefloxacin, and moxifloxacin. Methods: During November 2007 to February 2008, conjunctival swabs taken from 148 eyes of 120 patients (60 females and 60 males) were inoculated onto 5% blood agar plates and chocolate gelos agar plates. Comparison of in vitro susceptibility profiles and MIC50 of gram-positive bacteria isolated (n= 168) to ofloxacin and ciprofloxacin (second-generation fluoroquinolones), lomefloxacin (third-generation fluoroquinolone) and moxifloxacin (fourth-generation fluoroquinolone), was determined using the MicroScan? semiautomatic system and E-test?. Results: One hundred sixty-eigth microorganisms were isolated in 96 samples from 148 eyes. The isolated species were Gram-positive (100%, 168 of the 168 isolates) and Staphylococcus epidermidis was the most frequently isolated organism, accounting for 61,91% (104 of the 168 isolates). The others gram-positive bacteria isolated were Staphylococcus aureus 33,33%(56), Staphylococcus saprofítico 2,38% (4) and Staphylococcus hominis 2,38% (4). The in vitro susceptibility rates to ofloxacin, ciprofloxacin, lomefloxacin and moxifloxacin was for Staphylococcus epidermidis 76,92% (80 of the 104 isolates), 76,92% (80), 84,62% (88) and 92,31% (96), and for Staphylococcus aureus 100% (56 of the 56 isolates), 100% (56), 100% (56), and 7,14% (4), respectively. The median, MIC50 and mode values of moxifloxcin were lower than ciprofloxacin for both bacteria tested. Potency studies indicated that moxifloxacin was statistically more potent than ciprofloxacin for Staphylococcus aureus (P Conclusions: Fluoroquinolones have activity against normal conjunctival flora of the patients undergoing cataract surgery. Based on this in vitro testing, the fourth-generation fluoroquinolone (moxifloxacin) showed a broad spectrum of activity and was more susceptible against gram-positive bacteria isolates than second-generation and third-generation fluoroquinolones, particularly for Staphylococcus aureus. Clinical studies will be required to confirm these results.