In Vitro Antimicrobial Activity of Quinolones Against Major Bacterial Isolates from the Ocular Surface Bacterial Flora of Tertiary Hospital Patients in Japan

To determine the antimicrobial activity of quinolones against major bacterial isolates from the ocular surface bacterial flora of patients in a tertiary hospital for selection of optimal antibiotic eye drop during the perioperative stage. The conjunctival sac scraping of 933 patients who underwent ophthalmic surgery was cultivated and bacterial species of the isolates were identified. The minimum inhibitory concentrations (MICs) of gatifloxacin (GFLX), moxifloxacin (MFLX), levofloxacin (LVFX), and tosufloxacin (TFLX) were measured by microdilution methods. The cumulative percentages of MICs of 4 quinolones against major bacteria were calculated. The concentrations of quinolones inhibiting 50% (MIC ) and 90% (MIC ) of the major bacteria were compared. The study mainly included 784 patients scheduled for cataract surgery, 73 for vitrectomy, 30 for corneal transplantation, 30 for conjunctival surgery, 11 for eyelid surgery. The most frequently isolated bacterium was coagulase-negative (CNS) (184 strains), followed by (107 strains), (33 strains), (18 strains), and (13 strains). The percentages of methicillin-sensitive CNS isolates for which MIC of GFLX, MFLX, LVFX, and TFLX was 0.06 μg/mL or less were 8.0%, 13.4%, 5.4%, and 63.4%, respectively. Similarly, the percentage for was 23.0%, 23.0%, 0%, and 35.6%, respectively. MIC of TFLX for and showed the lowest values, 0.12 and 0.25 μg/mL, respectively. Among 4 quinolones, TFLX has the highest antimicrobial activity against major bacterial isolates from the ocular surface bacterial flora of patients in a tertiary hospital.