In vitro activity of ceftriaxone plus tazobactam against members of Enterobacteriaceae

To study the in vitro activity of ceftriaxone alone and in combination with the beta-lactamase inhibitor tazobactam against bacterial isolates belonging to the Family Enterobacteriaceae. One hundred and five consecutive isolates of Escherichia coli and Klebsiella spp. that had been recovered from various high-risk areas of the hospital were included in the study. MIC estimation to ceftriaxone and a combination of ceftriaxone and tazobactam was performed by the agar dilution method. By the MIC studies, 88.6% of the strains appeared to be resistant to ceftriaxone with the MIC90 value being > 256 microg/ml. When the MIC were done to ceftriaxone in combination with tazobactam, the resistance rate dropped to 4.8% with the MIC90 value being 4.0 microg/ml. The combination of ceftriaxone and tazobactam appears to be an excellent therapeutic alternative with 94.6% of ceftriaxone resistant strains being susceptible in vitro to this combination.