[Study of different methods in reducing conjunctival bacteria before cataract surgery].

OBJECTIVE

To study the conjunctival bacteria flora in eyes of patients undergoing cataract surgery and determine the efficacy of reducing conjunctival bacteria with different methods.

METHODS

A total of 135 eyes of 135 patients scheduled to undergo cataract surgery were randomized into 3 groups (45 each). They received topical prophylactic treatment with three different kinds of antibiotics (0.5% levofloxacin, 0.3% levofloxacin and 0.3% tobramycin). Each group was randomized into one-day group and three-day group. All the eyes underwent irrigation of fornices with 2.5% povidone-iodine (PVI) before surgery. Conjunctival cultures were obtained at various time points.

RESULTS

The total positive rate of conjunctival cultures was 66.7%. The eliminating rate of conjunctival bacteria in one-day groups were 72.7%, 72.7% and 61.1% (P = 0.667) while 70.0%, 70.0% and 55.5% in the three-day groups respectively (P = 0.751). Immediately after PVI irrigation, the eliminating rate in one-day groups added up to 86.4%, 77.3% and 88.9% (P = 0.564) as compared with 90.0%, 80.0% and 66.7% in the three-day groups respectively (P = 0.749). And there was no statistically significant difference between one-day groups and three-day groups in the eliminating rate of conjunctival bacterial after the topical antibiotic application. The MIC test revealed that the antibiotic sensitivity of Gram-positive cocci (G(+)C) to levofloxacin was 94.8% versus 74.1% to tobramycin (P = 0.000) while the antibiotic sensitivity of Gram-negative bacillus (G(-)B) to levofloxacin was 94.4% versus 83.3% to tobramycin (P = 0.289).

CONCLUSION

G(+)C accounts for the most among the conjunctival bacteria flora in eyes of patients undergoing cataract surgery and there is no statistically significant difference in the efficacy of reducing conjunctival bacteria between the application of topical antibiotic for one day and for three days. Both G(+)C and G(-)B retain a high sensitivity to levofloxacin. Topical antibiotic in combination with 2.5% PVI irrigation further reduces conjunctival bacteria.