Induced Resistance of Ocular Surface Flora in Patients Undergoing Cataract Surgery.

Purpose: This study investigated the effects of pre-operative topical moxifloxacin prior to cataract surgery on the growth of ocular surface bacteria and induced antibiotic resistance after a 3-day course of moxifloxacin.

Methods: The study was a prospective, dual arm, randomized study. The study group of 17 patients used moxifloxacin four times daily, for three days prior to surgery. The control group of 11 patients used no topical antibiotics prior to surgery. Patients' surgical eye was swabbed within sixty days of surgery at the pre-operative appointment and again the morning of surgery prior to surgical prep.

Results: The morning of surgery 100% of control patients and 52% of study patients (p=0.0097) had ocular surface bacterial growth. No patients had moxifloxacin resistant ocular surface bacteria prior to the start of the study. On the morning of surgery, 17% (3 patients) in the study group had moxifloxacin resistant ocular surface bacteria, compared to no patients in the control group (p=0.2579).

Conclusions: Although short-course pre-operative antibiotics reduce ocular surface bacterial growth, they do not eradicate it in the majority of patients. This could explain why topical antibiotics are less effective than intracameral antibiotics. Further, pre-operative antibiotic use may induce antibiotic resistance and may negatively affect the capabilities of intracameral antibiotics in endophthalmitis prevention and treatment.