Antibacterial properties of lidocaine on bacteria isolated from dermal lesions.

We studied the antibacterial properties of lidocaine and lidocaine with methylparaben, employing bacteria that were isolated from dermal lesions. Our study was significant because local anesthetics utilized before obtaining material for biopsy and/or culture may result in false-negative results. Killing curves were calculated to ascertain exposure times of bacteria to various concentrations of lidocaine with and without methylparaben that could affect recovery of viable bacteria from clinical specimens. The bacteria studied varied greatly in their susceptibility to lidocaine, with Neisseria species being the most sensitive. Greater inhibitory activity was noted against bacteria when methylparaben was present. Our study suggests that lower concentrations of lidocaine without methylparaben should be employed.