Treatment of ESBL-producing Klebsiella pneumoniae bacteraemia with carbapenems or flomoxef: A retrospective study and laboratory analysis of the isolates

Objectives: To better understand the clinical outcomes of patients with extended-spectrum b-lactamaseproducing Klebsiella pneumoniae (ESBL-KP) bacteraemia treated with either flomoxef or a carbapenem,and to evaluate the in vitro activities of these antibiotics against ESBL-KP. Methods: Retrospective analyses to identify risk factors for mortality in patients with flomoxefsusceptible ESBL-KP, especially addressing the therapeutic roles of flomoxef and carbapenem. In vitro activities of flomoxef and carbapenem against flomoxef-susceptible ESBL-KP isolates were evaluated by susceptibility testing and time-kill study. Results: Twenty-seven patients (flomoxef group, n = 7; carbapenem group, n = 20) were included. Clinical severity reflected by high Pitt bacteraemia score (≥6) was an independent risk factor for mortality (OR 13.43; 95% CI, 1.08-166.73; P = 0.043), while use of flomoxef or a carbapenem was not. The MICs of flomoxef and carbapenem indicated that the tested ESBL-KP were susceptible to these antibiotics regardless of the inoculum size of 10⁵ or 10⁷ cfu/mL. Time-kill study showed that these antibiotics (flomoxef 8 mg/L and meropenem 4 mg/L) each acted actively against and inhibited the regrowth of the tested ESBL-KP for at least 24 h. Conclusions: Flomoxef might be as clinically effective as a carbapenem in treating flomoxef-susceptible ESBL-KP bacteraemia.