The Efficacy of Breast Implant Irrigant Solutions in Gram-Negative Infections: An In-Vitro Model
Michael Ha1, Ledibabari M. Ngaage1,2, Peter C. Kim3, Richard D. Smith3, Jerilyn R. Izac3, Sheri Slezak3, Robert K. Ernst3, Janette Harro3, Yvonne M. Rasko1
1Division of Plastic Surgery, Department of Surgery, University of Maryland School of Medicine, Baltimore, 2Department of Plastic and Reconstructive Surgery, Johns Hopkins University, Baltimore, 3Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, Baltimore
Background: 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 at the time of placement. Recent literature has addressed the efficacy of irrigant solutions in gram-positive bacterial strains. However, there remains little data on the utility of irrigant solutions on gram-negative species associated with breast implant infection.
Methods: The authors assessed the relative efficacy of 10% povidone-iodine, triple-antibiotic solution, Prontosan, Clorpactin and normal saline (negative control) against three gram-negative species: Escherichia coli, Pseudomonas aeruginosa and Proteus species. Two strains were selected for each species, a stock strain and a clinical isolate. Sterile, smooth implant disks were immersed in each irrigant solution and then incubated in 3 x 10^7 suspensions of each bacterial strain overnight at 37°C. Each disk was then rinsed with 10mL sterile phosphate-buffered saline (PBS) and were sonicated in 1mL of PBS for 10 minutes to displace biofilm forming bacteria from the implant surface. The displaced bacteria were then quantified, and normalised values were calculated for the bacterial counts of each irrigant immersion.
Results: Povidone-iodine resulted in the greatest reduction of bacterial load for all six strains, significantly decreasing their bioburden by a factor of 10^1 to 10^6. In comparison, Prontasan had a lesser, yet still significant reduction in all bacterial strains except in one P. aeruginosa strain, in which it had no significant activity. Triple-antibiotic solution saw a ten-fold reduction on bacterial counts in one strain each of E. coli and P. aeruginosa. Clorpactin demonstrated no significant efficacy at reducing bacterial counts as compared to the saline control. No significant differences were observed when comparing the stock bacterial species and the clinical isolates.
Conclusions: Povidone-iodine has been proven the most effective and reducing bacterial contamination of Escherichia coli, P. aeruginosa and Proteus species. Alongside its proven utility against gram-positive bacteria, it may prove to be an effective prophylactic irrigant against breast implant infections. With the U.S. Food and Drug Administration recently lifting its moratorium, the field may benefit from larger clinical studies of povidone-iodine as a breast implant irrigant solution.
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