An In Vitro Model of the Efficacy of Breast Implant Irrigant Solutions Against Gram-Negative Infections

Abstract

Background In implant-based breast surgery, infections remain a clinically challenging complication. Surgeons often prophylactically address this risk by irrigating the implant at the time of placement. However, there remain few data on the ideal irrigant for gram-negative species. Methods The authors assessed the relative efficacy of 10% povidone-iodine, triple-antibiotic solution, Prontosan, Clorpactin, and normal saline (negative control) against 3 gram-negative bacterial backgrounds: Escherichia coli, Pseudomonas aeruginosa, and Proteus species. A laboratory-adapted strain and a clinical isolate were selected for each group of bacteria. Sterile, smooth implant discs were immersed in each irrigant solution and then incubated in suspensions of each bacterial strain overnight at 37°C. Each disc was then rinsed and sonicated to displace biofilm-forming bacteria from the implant surface. The displaced bacteria were enumerated by plating, and normalized values were calculated for the bacterial counts of each irrigant. Results Povidone-iodine resulted in the greatest reduction of bacterial load for all 6 strains by a factor of 101 to 106. Prontosan had a lesser, yet significant reduction in all bacterial strains. Triple-antibiotic solution demonstrated the greatest reduction in one Proteus species strain, and Clorpactin reduced bacterial counts in only half of the bacterial strains. When comparing laboratory strains to clinical isolates, significant differences were seen in each bacterial species in at least 2 irrigant solutions. Conclusions Povidone-iodine has been proven the most effective at reducing bacterial contamination of E. coli, P. aeruginosa, and Proteus species in both laboratory-adapted strains and clinical isolates. Clinical Relevance This study proves that povidone-iodine is the most effective at preventing gram-negative infections in breast implant surgery.