Bactericidal activity and killing rate of serum in volunteers receiving vancomycin or teicoplanin with and without amikacin given intravenously.

We have studied the interaction between vancomycin or teicoplanin and amikacin in two groups of five volunteers randomized to receive either (a) vacomycin, amikacin, vancomycin+amikacin, or (b) teicoplanin, amikacin, teicoplanin+amikacin. Each administration was given on separate days, in random order with a 48 hours washout period between each infusion. The serum concentrations measured microbiologically at time 0, 1 and 6 h were: 42.6, 11.4 and 4.1 mg/l respectively for teicoplanin; 27.6, 13.9, and 4.2 mg/l for vancomycin, and 44.9, 17.8, and 1.9 mg/l for amikacin. Teicoplanin was also measured using a solid-phase enzyme-receptor assay (SPERA). The serum bactericidal titres and the rate of killing in serum were measured 1 and 6 h after infusion against Staphylococcus aureus susceptible or resistant to oxacillin (5 strains each), S. epidermidis susceptible and resistant to oxacillin (5 strains each), Corynebacterium JK (5 strains), Listeria monocytogenes (5 strains), and Mycobacterium fortuitum (3 strains). The addition of amikacin to either teicoplanin or vancomycin increased the serum bactericidal titres against staphylococci with the exception of oxacillin-resistant S. epidermidis. Teicoplanin+amikacin was the most active regimen against L. monocytogenes and was equivalent to vancomycin+amikacin against M. fortuitum. Teicoplanin alone and teicoplanin+amikacin had a significantly lower killing rate against staphylococci than amikacin alone.