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To investigate how the pre-operative use of topical moxifloxacin prior to cataract surgery affects the ocular surface flora, and to determine if its use selects for resistant strains of ocular surface bacteria.
Conjunctival culture swabs were obtained at the pre-operative visit prior to cataract surgery and again the morning of cataract surgery in 17 patients who used topical moxifloxacin prior to surgery and in 11 control patients who did not use moxifloxacin prior to surgery. In the 17 patients who were prescribed topical moxifloxacin, they were instructed to use the medication four times daily for three days before surgery. Culture results from the study and control groups were analyzed for bacterial species growth and resistance patterns, determined by MALDI-TOF and antibiotic sensitivity analysis.
In the 17 patients who used topical moxifloxacin prior to cataract surgery, 9 of 17 (52%) had persistent ocular surface bacterial growth. All control patients had persistent bacterial growth (p = 0.0097). Bacterial resistance to moxifloxacin developed in 17.6% patients using moxifloxacin; no resistance to moxifloxacin developed in the control patients (p = 0.2579). Coagulase-negative staphylococci were the most commonly cultured bacterial species in both groups. Staphylococcus epidermidis grew in 86% of positive cultures (82% in the moxifloxacin group and 91% in the controls). Other common bacterial species in both groups were corynebacterial species (32%) and Staphylococcus aureus (21%).
Topical moxifloxacin use prior to cataract surgery does not reduce growth of ocular surface flora effectively in most patients, and its use may select for resistant strains of bacteria which could lead to reduced efficacy of intracameral moxifloxacin at the time of surgery. A larger study is indicated to further investigate these effects.