Susceptibilities of gentamicin-resistant Gram-negative aerobic bacilli to cefotetan and other beta-lactams.

The activity of the 7 alpha-methoxycephalosporin, cefotetan was determined against 365 infecting isolates of gentamicin- and multiply-resistant Gram-negative aerobic bacilli, and compared with those of cefuroxime, cefoxitin, cephradine, cefotaxime, ceftriaxone and ceftazidime. All proteus (4), providencia (6) salmonella (3) and serratia (2) were susceptible to 8 mg/l of cefotetan, as were respectively 90 and 81% of 42 Escherichia coli and 16 citrobacter isolates. The intrinsic activity of cefotetan was high against 237 klebsiellae (38 different serotypes), only 4 being relatively insusceptible (MICs 16- greater than 32 mg/l). Activity against pseudomonas (10 isolates) acinetobacter (15 isolates) and enterobacter (30 isolates) was poor. Overall, the activities of cefotetan were similar to those of cefotaxime, ceftriaxone and ceftazidime but ceftazidime was also active against the majority of pseudomonas, acinetobacter and enterobacter. Cefotaxime was less active than cefotetan against some cefuroxime-resistant klebsiellae. Much greater numbers of isolates were insusceptible to either cefuroxime or cefoxitin. Cephradine was the least active.