IN-VITRO ACTIVITY OF CEFTRIAXONE COMBINED WITH TAZOBACTAM AGAINST ANAEROBIC-BACTERIA

The in vitro activity of ceftriaxone combined with tazobactam against 190 strains of anaerobic bacteria was compared with that of amoxicilli n with clavulanic acid, ampicillin with sulbactam, piperacillin alone and with tazobactam, cefoxitin, and imipenem, i.e. beta-lactam antibio tics established in the treatment of anaerobic infections. All anaerob es tested were susceptible to less-than-or-equal-to 32 mg/l ceftriaxon e when tazobactam was added at fixed ratios (ceftriaxone to tazobactam ) of 2:1 and 8:1 and at constant concentrations of 2,4 and 8 mg/l, res pectively. When 4 mg/l tazobactam was added, the MICs of ceftriaxone f or 83 of 94 strains of the Bacteroides fragilis group were reduced by a factor of 8 to 512; for eight strains, this reduction was two to fou rfold. Only the MICs of ceftriaxone for three Bacteroides fragilis str ains were not influenced.