Antimicrobial activity of bupivacaine and morphine

Antimicrobial activity of bupivacaine and morphine against 10 microbial strains was studied with an agar dilution method. The strains tested were Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 25923), and one of each of the clinical isolates of Staphylococcus epidermidis (a multiresistant strain), Staphylococcus epidermidis (a sensitive strain), Streptococcus pneumoniae, Streptococcus pyogenes (A), Streptococcus faecalis, Bacillus cereus, and Candida albicans. The antimicrobial effect of bupivacaine was tested at concentrations of 0.5, 1.25, 2.5, and 5 mg/ml (0.05% 0.125%, 0.25%, and 0.5%). Bupivacaine at a concentration of 2.5 mg/ml inhibited the growth of the sensitive S. epidermidis strain, S. pyogenes, and S. pneumoniae, and all of the others except P. aeruginosa at a concentration of 5 mg/ml. Morphine 0.2 and 2 mg/ml (0.02 and 0.2%) did not inhibit any of the strains.