Effect of topical netilmicin on the reduction of bacterial flora on the human conjunctiva

PURPOSE: To investigate the effects of topical netilmicin on human conjunctival bacterial flora. METHODS: Fifty-six patients' eyes with cataract were treated three times a day with netilmicin 1 day before the surgery. The fellow eyes of the patients were not treated. After 1 day of netilmicin application cultures of the inferior palpebral conjunctiva were performed in both eyes. Bacterial evaluation is qualitative. McNemar test was used for statistical analyses. RESULTS: The number of eyes with positive culture for coagulase negative staphylococcus (CNS) in untreated eyes was 43 (76.8%) and in treated eyes it was 5 (8.93%) and the difference was statistically significant (p=0.000). In untreated eyes number of negative cultures with no bacterial growth was 8 (14.3%) and it was 47 (83.9%) in the treated eyes. The difference among groups was statistically significant (p=0.000). Netilmicin is found very effective for CNS as the percentage of positive cultures (n=43) in untreated eyes to positive cultures (n=4) in the treated fellow eye was 90.7%. Likewise, all patients with Staphylococcus aureus positive cultures in untreated eyes (n=5) had negative culture for this microorganism in their treated fellow eyes (100%). CONCLUSIONS: The Endophthalmitis Vitrectomy Study demonstrated that the most common causes of postoperative endophthalmitis are coagulase negative microorganisms, S aureus and Streptococcus species. As netilmicin was found effective to reduce the number of positive cultures for these bacteria, it can be used to lower the incidence of postoperative endophthalmitis before surgery.