Comparative study of gentamycin and povidone-iodine on eliminating the conjunctival bacteria

Abstract

To study the efficacy of gentamycin, 0.5% povidone-iodine and 5.0% povidone-iodine in eliminating rate of positive conjunctival bacteria cultures and aqueous humor contamination, and to observe their adverse effects. It was a comparative study. Three hundred patients (300 eyes) were randomized to three groups: gentamycin group, 0.5% povidone-iodine group and 5.0% povidone-iodine group. All patients received 1-day (6 times) topical application of 0.3% ofloxacin before surgery. Approximately 5 minutes before surgery, the conjunctival sac was irrigated with 5 - 8 ml gentamycin, 0.5% povidone-iodine or 5.0% povidone-iodine, correspondingly. Conjunctival cultures were obtained at the following time points: before receiving any topical medications; after application of 1-day topical 0.3% ofloxacin, before irrigating the conjunctival sac; immediately before surgery approximately 5 minutes after conjunctival sac irrigation and at the end of the surgery. Anterior chamber aspirates were obtained at the beginning of the surgery. Bacteria isolated were identified and antibiotic susceptibility was determined. The rate of positive conjunctival cultures among each group was compared and significance of the difference was tested with the Pearson chi-square test. Rate of positive conjunctival cultures before the conjunctival irrigation was 79.7%, 76.6% and 77.8% in the gentamycin group, 0.5% povidone-iodine group and 5.0% povidone-iodine group, respectively. The difference between these three groups was not statistically significant (chi2 = 0.28, P = 0.86). At the end of surgery, the rate of positive conjunctival cultures in these three groups was 11.7%, 8.3% and 6.3%, respectively. The difference between these three groups was also not statistically significant (chi2 = 1.74, P = 0.41). The average rate of anterior aqueous contamination was 4.9% and there was no significant difference among these three groups (P > 0.05). Both 0.5% povidone-iodine and 5.0% povidone-iodine using for irrigating conjunctival sac are safe. Gentamycin, 0.5% povidone-iodine and 5.0% povidone-iodine have similar effects on the reduction of the bacteria in conjunctival sac.