The Ideal Degree Of Dilution For Povidone-iodine As A Breast Implant Irrigant Solution: An In-vitro Model
Michael Ha, MA Cantab MB BChir1, Ledibabari M. Ngaage, MA Cantab MB BChir2, Richard D. Smith, BS3, Jerilyn R. Izac, PhD3, Sheri Slezak, MD1, Robert K. Ernst, PhD3, Janette Harro, PhD3, Yvonne M. Rasko, MD1.
1University of Maryland, School of Medicine, Baltimore, MD, USA, 2Johns Hopkins University, Baltimore, MD, USA, 3University of Maryland, Baltimore, Baltimore, MD, USA.
PURPOSE: In implant-based breast surgery, infections remain a challenging complication, leading to significant clinical and financial consequences. Surgeons may choose to prophylactically address this risk by irrigating the implant with povidone-iodine at the time of placement. However, there remains little consensus regarding the optimal dilution of povidione-iodine for optimal efficacy.
METHODS: The authors assessed the efficacy of 10% povidone-iodine at three potential dilutions (100%, 50% or 25% strength) against four groups of bacteria: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. Normal saline was included as a negative control. Sterile, smooth implant disks were immersed in each irrigant solution and then incubated in suspensions of each bacterial strain overnight at 37°C. Each disk was rinsed and the sonicated to displace biofilm forming bacteria from the implant surface. The displaced bacteria were quantified, and normalized values were calculated for the bacterial counts of each irrigant immersion.
RESULTS: Across all strains of both Gram-positive and Gram-negative bacteria, povidone-iodine resulted in lower reduction of bacterial load at greater levels of dilution. A dilution of 25% led to a moderate bacterial load reduction of 103 to 104 in three of our bacterial strains, but no significant reduction in Pseudomonas. For 50% and 100% strength, we noted a reduction of 101-105 of all bacterial counts, with no significant difference between the dilutions.
CONCLUSION: As we strive to conserve resources in breast surgery, we can recommend that diluting povidone-iodine in equal parts saline does not reduce the efficacy of its anti-microbial properties.
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