Antibacterial activity of lidocaine in mixtures with Diprivan

We have studied the antibacterial activity of different concentrations of:0.005-2% lidocaine (lignocaine) in mixtures with Diprivan (propofol), against micro-organisms commonly implicated in sepsis as a result of extrinsically contaminated Diprivan. Bacterial colony counts were reduced progressively with increasing concentrations of lidocaine. Bacteriostatic and bactericidal concentrations of lidocaine were 0.2-2%. Lidocaine 2% was not bactericidal for one of the seven organisms tested. By inhibiting bacterial replication, lidocaine, when added to Diprivan to reduce pain on injection, may possibly reduce the harmful consequences if extrinsic contamination occurs.