The antibacterial effects of tumescent liposuction fluid

Tumescent liposuction is currently one of the most commonly performed aesth etic procedures. Despite the variable rue of preoperative antibiotics, infe ction is uncommon. Prior works suggest that the low incidence of infection may be due to lidocaine's antibacterial properties. However, these prop el- ties have only been demonstrated using concentrations of lidocaine above 0. 8%, significantly higher than those used in tumescent liposuction. The purp ose of this study was to determine if the commonly used tumescent fluid con taining 0.1% lidocaine, 1:1000,000 epinephrine, and 0.012 mEq sodium bicarb onate possesses antibacterial activity. Using the broth microdilution metho d, the minimum inhibitory concentrations of Escherichia coli, Proteus mirab ilis, Pseudomonas aeruginosa, Staphylococcus aureus, and Group A beta-hemol ytic Streptococcus were determined after exposure to either lidocaine, epin ephrine, bicarbonate, or the combination of all three agents. To determine if there were significant growth differences not detectable by the broth mi crodilution method, bacterial concentrations were obtained through the use of a spectrophotometer, and significant differences fi om the controls were calculated by one-way analysis of variance. To determine if prolonged expo sure to the tumescent mix would alter bacterial growth, a Killing Time stud y was also undertaken. The results indicated that the minimum inhibitory co ncentration of lidocaine was not less than 0.5% for any of the bacteria, wh ereas the lowest minimum inhibitory concentration of the combined solution was 0.25%. The lowest inhibitory concentration as determined by spectrophot ometric analysis for the combined solution was 0.13% (p < 0.01). Analysis o f the Killing Time data revealed no inhibition of bacterial growth over tim e. In conclusion, lidocaine, epinephrine, and bicarbonate do exhibit antiba cterial properties at high concentrations. However, the commonly used tumes cent mixture containing dilute concentrations of these agents does not sign ificantly inhibit the growth of commonly encountered bacteria.