oa Southern African Journal of Anaesthesia and Analgesia - Alkalinisation does not enhance the antimicrobial properties of local anaesthetic solutions : original research
Background The purpose of the study was to examine the previously reported finding that the addition of bicarbonate to lignocaine enhanced the antimicrobial effect of the local anaesthetic agent on a range of bacteria implicated in epidural infections and to determine if this would also hold true for bupivacaine.
Methods Bupivacaine at a concentration of 0.25% and lignocaine at a concentration of 1% with and without an alkaline buffer were inoculated with suspensions of Staphylococcus epidermidis, Staphylococcus aureus or Escherichia coli. The mixtures were plated on 2% blood agar plates immediately (T = 0) and after 24 hours at room temperature (T = 24), and numbers of colonies were recorded. The difference in the number of colonies between T = 0 and T = 24 was expressed as a fraction of the T=0 value, giving a percentage inhibition of colony growth. Statistical testing was performed using Kruskal-Wallis non-parametric One Way Analysis of Variance (ANOVA) followed by multiple comparisons of mean ranks between all groups.
Results At concentrations of 0.25% bupivacaine and 1% lignocaine, these findings suggest that 1% lignocaine has no antibacterial activity. The addition of bicarbonate has no influence.
Conclusions Bupivacaine has significant antibacterial activity, but the addition of bicarbonate has no influence.
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