AIM:To evaluate the
antibacterial activities of
mezlocillin/tazobactam (MLN/TAZ) in vivo and in vitro. METHODS:The antibacterial
activity of MLN/TAZ (1 : 0,2 : 1,4: 1) were tested by the method of minimal inhibitory concentration (MIC),minimal bactericidal concentration (MBC) and time-kill curve in vitro. The influence of pH and inoculation quantity on MIC was also observed in vivo ,the optimum proportion of MLN/ TAZ was evaluated by the acute infection models that were established in mice with E. Coli 1200 producing ES-BLs. RESULTS:When proportion of MLN/TAZ at 2 : 1 and 4 : 1,the
antibacterial activities were significantly increased (P < 0.01) compared with MLN. The antibacterial activities of MLN/TAZ decreased to the lowest point under pH 7.0 and MIC was increased when the inoculation quantity increased. Median effective doses of MLN/ TAZ (2 : 1,4 : l)were 29.1 % and 27.3 % of
mezlocillin respectively in infection model. CONCLUSION: MLN/TAZ at the proportion of 4 : 1 has the optimum antibacterial activity.