Antibacterial Activity of Lidocaine in Combination with a Bicarbonate Buffer

Abstract

BACKGROUND: The antibacterial properties of lidocaine have been previously described. Recent reports indicated that the addition of NaHCO3 to lidocaine reduces the pain associated with the injection. This study was conducted to determine the antibacterial activity of lidocaine buffered with NaHCO3. METHODS: Rates of killing of six species of bacteria were determined in the presence of buffered and unbuffered lidocaine. When bacteria were incubated with lidocaine buffered with NaHCO3 at either 25, 50, or 100 mEq/L, there was a decrease of > 99% of all bacteria tested over the 6 hours of the assay. This dramatic rate of killing was not observed in the unbuffered control preparations. RESULTS: The results of this study indicate that NaHCO3 enhances the killing effect that has been described for lidocaine alone. The inability to recover common pathogenic bacteria from biopsy specimens could be the result of exposure to local anesthetic agents such as lidocaine that are buffered with NaHCO3.