The Clinical Evaluation of Third-generation Cephalosporins As Definitive Therapy for Enterobacter spp. and Klebsiella aerogenes Bacteremia

Objective Third-generation cephalosporins (3GCs) may be susceptible in vitro to Enterobacter spp. and Klebsiella aerogenes. However, treatment with mainly fourth-generation cephalosporins or carbapenems is currently recommended. Diversification of antimicrobial agents in therapy is required to avoid the selection pressure of resistant organisms by broad-spectrum antimicrobial agents. This study investigated the clinical efficacy of 3GC therapy for Enterobacter spp. and Klebsiella aerogenes bacteremia in a multicenter, retro-spective, observational study.Methods Patients with Enterobacter spp. or Klebsiella aerogenes detected in blood cultures and treated with a susceptible antimicrobial agent were included in the study. Propensity score matching was performed to align patient background bases, and clinical outcomes between the 3GC and non-3GC groups were com-pared. Treatment success was defined as having no need for treatment escalation or the addition of other an-timicrobial agents, no recurrence, or no death within 30 days.Results The study included 188 cases, of which 57 and 131 were included in the 3GC and non-3GC treat-ment groups, respectively; 53 patients in each group were matched by propensity score matching. There were no significant differences between groups in rates of switching to a susceptible antimicrobial or adding an-other agent, relapse within 30 days, or death within 30 days. In the 3GC group, source control was associ-ated with favorable clinical outcomes. Conclusion Definitive 3GC therapy for susceptible Enterobacter spp. and Klebsiella aerogenes bacteremia is as clinically effective and valuable a targeted therapy as non-3GC therapy and can be implemented under conditions in which infection source control measures are in place.