Céfoxitine et BLSE

Pharmacokinetics, efficacy and tolerance of cefoxitin in the treatment of cefoxitin-susceptible extended-spectrum beta-lactamase producing Enterobacterales infections in critically ill patients: a retrospective single-center study

BACKGROUND

Cefoxitin is active against some extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE), but has not been evaluated so far in the intensive care unit (ICU) settings. Data upon its pharmacokinetics (PK), tolerance and efficacy in critical conditions are scanty. We performed a retrospective single-center study in a university hospital medical ICU, in subjects presenting with cefoxitin-susceptible ESBL-PE infection and treated with cefoxitin. The primary aim was to determine cefoxitin PK. Secondary endpoints were efficacy, tolerance, and emergence of cephamycin-resistance.

RESULTS

Forty-one patients were included in this study, mainly with ESBL-PE pneumonia (35 patients, 85%). Cefoxitin was administered during a median [interquartile range (IQR)] duration of 5 [4-7] days. Cefoxitin serum concentrations strongly depended on renal function. Target serum concentration (> 5 × minimum inhibitory concentration (MIC) 24 h after cefoxitin onset was obtained in 34 patients (83%), using a median [IQR] daily dose of 6 [6-6] g with continuous administration. The standard dosage of 6 g/24 h was not sufficient to achieve the PK/PD target serum concentration for MIC up to 4-8 mg/L, except in patients with severe renal impairment and those treated with renal replacement therapy. Treatment failure occurred in 26 cases (63%), among whom 12 patients (29%) died, 13 patients (32%) were switched to alternative antibiotic therapy and 11 patients (27%) presented with relapse of infection with the same ESBL-PE. Serious adverse events attributed to cefoxitin occurred in 7 patients (17%). Acquisition of cephamycin-resistance with the same Enterobacterales was identified in 13 patients (32%), and was associated with underdosage.

CONCLUSION

Continuous administration of large doses of cefoxitin appears necessary to achieve the PK/PD target in patients with normal renal function. Renal status, MIC determination and therapeutic drug monitoring may be useful for treatment individualization in this setting. The treatment failure rate was 63%. The cefoxitin safety profile was favorable, but we observed a high rate of cephamycin-resistance emergence.

Cefoxitin as a carbapenem-sparing antibiotic for infections caused by extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae

BACKGROUND

Cefoxitin has demonstrated in vitro resistance to hydrolysis by extended-spectrum beta-lactamases.

METHODS

We evaluated the microbiological and clinical efficacy of cefoxitin in 33 patients treated for an infection related to extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E). Clinical and microbiological outcomes were assessed from the initiation of cefoxitin therapy to the latest information available in the patient's medical file.

RESULTS

The 33 patients were mainly males (n = 26), aged 70 years (median, minimum-maximum: 23-93) and main sites of infection were urinary (n = 23) and catheter-related bloodstream infections (n = 4). Escherichia coli and Klebsiella pneumoniae were isolated in 19 and 14 subjects, respectively. The clinical outcome was favorable in 30 of 33 patients in the first 48 h after the start of cefoxitin, and in 20 (of 24 evaluable) at the end of follow-up. Six microbiological failures were documented and resistance to cefoxitin emerged in two strains of K. pneumoniae.

CONCLUSIONS

Cefoxitin could be considered as a carbapenem-sparing antibiotic for some ESBL-E infections, preferentially those related to E. coli.

Pharmacological study of cefoxitin as an alternative antibiotic therapy to carbapenems in treatment of urinary tract infections due to extended-spectrum-β-lactamase-producing Escherichia coli

Cefoxitin could be an alternative to carbapenems in extended-spectrum-beta-lactamase-producing Escherichia coli (ESBL-EC) infections. However, pharmacological and clinical data regarding cefoxitin are limited. Using a recent pharmacological model and the MICs of ESBL-EC collected from pyelonephritis, we determined the probabilities to reach four pharmacological targets: free cefoxitin concentrations above the MIC during 50% and 100% of the administration interval (T>MIC = 50% and T>MIC = 100%, respectively) and free cefoxitin concentrations above 4× MIC during 50% and 100% of the administration interval (T>4MIC = 50% and T>4MIC = 100%, respectively). Cefoxitin could be used to treat ESBL-EC pyelonephritis, but administration modalities should be optimized according to MICs in order to reach pharmacological targets.