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Study: Povidone-iodine 5% more effective than 1% on heavy bacterial loads
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STIRLING, Scotland — Povidone-iodine 5% is more effective than povidone-iodine 1% in decreasing conjunctival bacterial flora, particularly in the presence of a heavy bacterial load, according to an in vivo study. The study authors note that these findings contradict studies performed with the two concentrations in vitro.
Andrew Ferguson and colleagues here at the Stirling Royal Infirmary conducted a prospective randomized double-blind study on 37 male and 67 female patients undergoing cataract surgery. Patients were randomized to have their conjunctival fornices irrigated preoperatively with povidone-iodine in either 5% or 1% solution. Conjunctival swabs were taken both before and 1 minute after irrigation.
The group given the 5% solution showed a decrease in median colony forming units (CFU) from 100 CFU before to 40 CFU after irrigation. The 1% solution group had a reduction from 120 CFU before to 100 CFU after irrigation. At higher bacterial loads (where pre-irrigation levels were higher than 1,000 CFU), the median difference between the two groups became larger as the number of pre-irrigation bacteria increased.
The study is published in the February issue of British Journal of Ophthalmology.