Risk factors for antibiotic-resistant conjunctival bacterial flora in patients undergoing intraocular surgery

Background. The purpose of this study was to determine if patients with certain risk factors are more likely to harbor conjunctival bacterial flora resistant to multiple antibiotics. Methods. In this prospective study, detailed medical history and slit-lamp examination were performed on all patients prior to intraocular surgery. Patients with local risk factors were defined as those with chronic blepharitis, conjunctivitis or discharge. Those with systemic risk factors were patients with diabetes, autoimmune, immunodeficient or skin disorders, asthma and those taking immunosuppressant medications. Conjunctival cultures were obtained prior to preoperative antibiotics and povidone-iodine. Bacteria isolated were identified and antibiotic susceptibility was determined. Bacteria resistant to five or more antibiotics were defined as multi-resistant (MR). Results. Among the 207 patients enrolled in the study, 73 patients had local risk factors. Of these patients, 32 patients (44%) carried MR organisms, compared to 32 of the 134 patients (24%) without local risk factors (P = 0.0049). Thirty-two of 71 patients (45%) with systemic risk factors harbored MR organisms, compared to 32 of 136 patients (24%) without systemic risk factors (P = 0.0025). Seventeen of 93 patients (18%) who had neither local nor systemic risk factors had MR organisms on their conjunctiva. In contrast, 17 of the 30 patients (57%) with both local and systemic risk factors (57%) carried MR bacteria (P = 0.0001). Conclusion. Patients with local and/or systemic risk factors are more likely to harbor MR organisms. This may be one mechanism for the reported increased risk of postoperative endophthalmitis in this group of patients.