Inhibition of povidone-iodine's bactericidal activity by common organic substances: an experimental study.

An in vitro study demonstrated that some organic substances commonly present in the surgical field inhibit the bactericidal activity of dilute povidone-iodine solutions. The degree of inhibition was inversely proportional to the concentration of the povidone-iodine solutions and it was greatest by blood, followed by pus, fat, and glove powder. The pattern of bacterial kill was virtually identical for all the strains tested. The most likely explanation for this phenomenon is that iodine is bound by the organic substances, decreasing the iodine available for bacterial kill. To obtain an optimal benefit, we suggest eliminating these substances from the operative site or wound when possible before the use of povidone-iodine solution.