title: Carbapenem therapy for bacteremia due to extended-spectrum-β-lactamase-producing Escherichia coli or Klebsiella pneumoniae: implications of ertapenem susceptibility.
abstract: A retrospective study was conducted at two medical centers in Taiwan to evaluate the clinical characteristics, outcomes, and risk factors for mortality among patients treated with a carbapenem for bacteremia caused by extended-spectrum-beta-lactamase (ESBL)-producing organisms. A total of 251 patients with bacteremia caused by ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates treated by a carbapenem were identified. Among these ESBL-producing isolates, rates of susceptibility to ertapenem (MICs ≤ 0.25 μg/ml) were 83.8% and 76.4%, respectively; those to meropenem were 100% and 99.3%, respectively; and those to imipenem were 100% and 97.9%, respectively. There were no significant differences in the critical illness rate (P = 0.1) or sepsis-related mortality rate (P = 0.2) for patients with bacteremia caused by ESBL-producing K. pneumoniae (140 isolates, 55.8%) and E. coli (111 isolates, 44.2%). Multivariate analysis of variables related to sepsis-related mortality revealed that the presence of severe sepsis (odds ratio [OR], 15.9; 95% confidence interval [CI], 5.84 to 43.34; P < 0.001), hospital-onset bacteremia (OR, 4.65; 95% CI, 1.42 to 15.24; P = 0.01), and ertapenem-nonsusceptible isolates (OR, 5.12; 95% CI, 2.04 to 12.88; P = 0.001) were independent risk factors. The patients receiving inappropriate therapy had a higher sepsis-related mortality than those with appropriate therapy (P = 0.002), irrespective of ertapenem, imipenem, or meropenem therapy. Infections due to the ertapenem-susceptible isolates (MICs ≤ 0.25 μg/ml) were associated with a more favorable outcome than those due to ertapenem-nonsusceptible isolates (MICs > 0.25 μg/ml), if treated by a carbapenem. However, the mortality for patients with bacteremic episodes due to isolates with MICs of ≤ 0.5 μg/ml was similar to the mortality for those whose isolates had MICs of >0.5 μg/ml (P = 0.8). Such a finding supports the rationale of the current CLSI 2011 criteria for carbapenems for Enterobacteriaceae.
authors.affiliation: Department of Internal Medicine and Center for Infection Control, National Cheng Kung University Medical College and Hospital, Tainan, Taiwan.
authors.forename: Nan-Yao
authors.initials: NY
authors.lastname: Lee
authors.forename: Ching-Chi
authors.initials: CC
authors.lastname: Lee
authors.forename: Wei-Han
authors.initials: WH
authors.lastname: Huang
authors.forename: Ko-Chung
authors.initials: KC
authors.lastname: Tsui
authors.forename: Po-Ren
authors.initials: PR
authors.lastname: Hsueh
authors.forename: Wen-Chien
authors.initials: WC
authors.lastname: Ko
mesh_terms: D000328:Adult; D016470:Bacteremia / Q000188:drug therapy* / Q000382:microbiology*; D000077727:Ertapenem; D004926:Escherichia coli / Q000187:drug effects / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology*; D005260:Female; D006801:Humans; D015378:Imipenem / Q000627:therapeutic use; D007710:Klebsiella Infections / Q000188:drug therapy / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000472:pathogenicity*; D008297:Male; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D012189:Retrospective Studies; D013845:Thienamycins / Q000627:therapeutic use; D055815:Young Adult; D047090:beta-Lactams / Q000627:therapeutic use
chemical_list: D013845:Thienamycins; D047090:beta-Lactams; D015378:Imipenem; D000077731:Meropenem; D000077727:Ertapenem