In vitro evaluation of broad-spectrum β-lactams tested in medical centers in Korea: role of fourth-generation cephalosporins

Abstract

Levels of resistance to the “third-generation” cephalosporins among isolates of clinical bacteria in Korea have been increasing at a rapid rate. This study evaluated the activity of cefepime, a “fourth-generation” cephalosporin, and six other broad-spectrum β-lactam antimicrobials (cefpirome, ceftazidime, ceftriaxone, imipenem, piperacillin/tazobactam [4 μg/mL fixed concentration], oxacillin) against 404 isolates of clinical bacteria from Korea. Susceptibility profiles of each isolate were established using the Etest (AB BIODISK, Solna, Sweden) method of susceptibility testing. Only the carbapenem imipenem was > 90% effective in inhibiting each of the species tested ( Escherichia coli, Klebsiella, spp., Citrobacter spp., Enterobacter spp., indole-positive Proteae, Serratia spp., Acinetobacter spp., Pseudomonas aeruginosa, and oxacillin-susceptible staphylococci). Imipenem was followed by cefepime > cefpirome > piperacillin/tazobactam > ceftazidime > ceftriaxone in overall rank order of usable spectrum against the isolates tested. Extended spectrum β-lactamase producing phenotypes were much more prevalent among the Klebsiella spp. (48.8%) than the E. coli (5.0%) isolates. Cefepime was much more active than cefpirome, 95.1% susceptible as compared with 70.7% susceptible, against the 41 isolates of Klebsiella spp. The results of this study corroborates findings from earlier studies with levels of resistance to the broad-spectrum β-lactams in Korea continuing to rise indicating the need for intervention strategies.