Activity of ertapenem, ciprofloxacin, ceftriaxone, piperacillin-tazobactam, and ampicillin-sulbactam against 12 common clinical isolates of community-acquired bacteremia

Background and purpose: To compare the antimicrobial activities of ertapenem, ciprofloxacin, ceftriaxone, piperacillin-tazobactam, and ampicillin-sulbactam against 12 common organisms that cause community-acquired bacteremia and to identify the most active agents for the treatment of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae. Methods: 1200 blood specimens from patients with community-acquired bacteremia were collected at Chang Gung Memorial Hospital, Kaohsiung, Taiwan. All isolates were identified by the API system, and each culture's antimicrobial susceptibility was determined by the standard disk-diffusion method. The minimal inhibitory concentrations of the antibiotics were detected by the Epsilimeter test. Results: The in vitro susceptibilities of 11 of the 12 common pathogens to ertapenem were 100%. The frequency of ESBL-producing E. coli and K. pneumoniae was 6.2% and 9.5%, respectively Only 48% and 50% of E. coli and K. pneumoniae, respectively, were susceptible to ciprofloxacin. These data infer that ciprofloxacin should not be given for ESBL-producing E. coli and K. pneumoniae. Ceftriaxone and piperacillin- tazobactam had high activity against the most common pathogens isolated. Conclusions: ESBL E. coli and K. pneumoniae are highly resistant to ciprofloxacin, so this antibiotic should be avoided for patients with community-acquired bacteremia. ESBL E. coli and K. pneumoniae are highly susceptible to ertapenem.