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A. Spano, Sr., L. Cerulli, S. Palma, C. Nucci, D. Molinaro, C. Varesi, G. Cappiello, S. Romano, M. Bernassola; Prevention of Endophthalmitis Following Cataract Surgery. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1140.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the efficacy of preoperative disinfection with povidone iodine in reducing the conjunctival and palpebral flora in patients undergoing cataract surgery and to evalute effectiveness of an alternative microbiological identification method using methods in molecular biology.
The study was conducted on 178 patients with cataracts (40-97 years) who underwent phacoemulsification.Swabs of the inferior fornix and the margin of the upper and lower eyelid were collected before the preoperative disinfection procedure. A second conjunctival swab was collected at the end of surgery. In 89 / 178 cases, a postoperative eyelid swab was also taken at this time. Automated species-level identification of cocci isolated from the cultures was made with the VITEK 2 system; the Phoenix system was used to identify non-cocci and for repeat testing of all isolates. The identity of all staphylococcal isolates was confirmed with rpoB gene sequencing assays. Genomic DNA was extracted from pure cultures of each isolate and purified with QIAamp DNA minikits. Ten microliters of DNA were amplified with 2491F-3554R primers for rpoB.
one third of the patients had positive preoperative conjunctival cultures. Staphylococcus epidermidis was the species most frequently isolated from these cultures (16.3%). Preoperative eyelid cultures were positive for 1 or more species in 156/178 patients,and here as well the predominant species isolated with S. epidermidis. The postoperative conjunctival specimen was sterile in the vast majority of cases (95.5%) In 89 of the 178 patients, postoperative eyelid swabs were also cultured. Analysis of the results for patients whose preoperative eyelid cultures were positive shows that intraoperative disinfection of the eyelid with povidone iodine 10% was unsuccessful in 21 / 71 cases. Comparison of the nucleotide sequences with those in the database confirmed that the isolates analyzed were indeed S. epidermidis..
Preoperative prophylaxis with povidone iodine can significantly reduce the frequency of bacterial contamination in the postoperative period. Although a few of the postoperative cultures were positive, these cases were characterized by substantial reduction of the bacterial load as compared with pre-prophylaxis specimens. Prolonging the tissues’ contact with the disinfectant might further reduce the bacterial load and with it the risk of endophthalmitis. Amplification and sequencing of an appropriate gene region is an alternative for accurate species-level identification of staphylococci.
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