How to optimize administration of cefoxitin for the treatment of extended spectrum producing Enterobacteriaceae-related infection?

Pharmacological and clinical data regarding cefoxitin for the treatment of ESBL-producing Enterobacteriaceae-related infections are limited. We performed a multicentric prospective cohort study to evaluate continuous/prolonged, or intermittent infusion of cefoxitin. We assessed the plasma concentration as a function of the duration of infusion and then performed a simulation of the percentage of patients who would reach the PK/PD targets, set at 100% ƒT> MIC or 100% ƒT>4 MIC. Eighty-one patients were included. All patients were treated with 6 gr./day. MICs to cefoxitin ranged from 0.5 to 64 mg/L. Sixteen (19.7%) patients were infected with strains with cefoxitin MICs ≥ 8 mg/L. In all patients infected with strains with MICs ≤ 6 mg/L, PK/PD objectives (100% ƒT> MIC) were achieved with prolonged or continuous infusion. In contrast, when MICs were 8 mg/L only, continuous infusion was sufficient to achieve the PK/PD objectives (100% ƒT> MIC). Extended infusion of cefoxitin is necessary for the treatment of non-UTI ESBL-related infections.