PURPOSE: To evaluate the conjunctival bacterial flora of healthy patients and its antibiotic resistance pattern and determine the effective of a regime of topical antibiotics on reduction of endogenous microbiota. METHODS: Its a prospective non randomized study. Fourty eyes of 40 patients, divided in 4 groups of 10 eyes each, used four differents topical antibiotics (ciprofloxacin, tobramycin and gatifloxacin). One group served as a control group. Were performed conjunctival cultures before instillation of the antibiotics drops and after 15, 30 and 60 minutes. Were performed susceptibility tests of the specimes isolated to these antibiotics. We compared the reduction of bacterium growth by assessing the number of UFC (colonies forming units) before and after the instillation of antibiotics drops. RESULTS: Of the 40 eyes, 92,5% had positive cultures. The coagulase-negative Staphylococcus (CNS) was the most frequent organism isolated (50%), followed by Staphylococcus Aureus (23%) and gram-negative bacteria (26%). More than 81% of the isolates of this bacterium were susceptible to all antibiotics tested. Five bacterium isolates were resistant to ciprofloxacin and tobramycin and two to gatifloxacin. All groups had diminished the number of patients with positive culture specimes from the conjuntiva compared to moment zero and to placebo. CONCLUSION: The gram positive bacterium, specially the coagulase-negative Staphylococcus, were the most frequent microorganism found on conjunctiva of healthy patients. The most of the bacterium isolated were sensitivity to the antibiotics tested. The proposed regime of use of these antibiotics reduced the number of UFC (colonies forming units) compared to placebo although without statics relevance in most of cases.
Conjunctiva; Antibiotic prophylaxis; Drug resistance; Cataract extraction; Endophthalmitis
