The antibacterial effects of tumescent liposuction fluid

Tumescent liposuction is currently one of the most commonly performed aesthetic procedures. Despite the variable use of preoperative antibiotics, infection is uncommon. Prior works suggest that the low incidence of infection may be due to lidocaine's antibacterial properties. However, these properties have only been demonstrated using concentrations of lidocaine above 0.8%, significantly higher than those used in tumescent liposuction. The purpose of this study was to determine if the commonly used tumescent fluid containing 0.1% lidocaine, 1:1000,000 epinephrine, and 0.012 mEq sodium bicarbonate possesses antibacterial activity. Using the broth microdilution method, the minimum inhibitory concentrations of Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, and Group A beta-hemolytic Streptococcus were determined after exposure to either lidocaine, epinephrine, bicarbonate, or the combination of all three agents. To determine if there were significant growth differences not detectable by the broth microdilution method, bacterial concentrations were obtained through the use of a spectrophotometer, and significant differences from the controls were calculated by one-way analysis of variance. To determine if prolonged exposure to the tumescent mix would alter bacterial growth, a Killing Time study was also undertaken. The results indicated that the minimum inhibitory concentration of lidocaine was not less than 0.5% for any of the bacteria, whereas the lowest minimum inhibitory concentration of the combined solution was 0.25%. The lowest inhibitory concentration as determined by spectrophotometric analysis for the combined solution was 0.13% (p < 0.01). Analysis of the Killing Time data revealed no inhibition of bacterial growth over time. In conclusion, lidocaine, epinephrine, and bicarbonate do exhibit antibacterial properties at high concentrations. However, the commonly used tumescent mixture containing dilute concentrations of these agents does not significantly inhibit the growth of commonly encountered bacteria.