Continuous infusion of cefiderocol in a critically ill patient with continuous venovenous haemofiltration.

Cefiderocol is a broad spectrum cephalosporin antibiotic and is indicated in patients with difficult-to-treat Gram-negative bacterial infections. Cefiderocol is applied as a 2 to 4 times daily prolonged 3-hour infusion. The therapeutic target of cefiderocol suggests that continuous infusion (CI) may be advantageous, since it is more likely to achieve 100% of time of the unbound concentration above the minimal inhibitory concentration (fT>MIC). Yet, limited information on cefiderocol as CI has been assessed. We present a case of a critically ill 37-year-old woman with continuous venovenous haemofiltration (CVVH) treated with a CI of cefiderocol for multi-drug resistant Pseudomonas aeruginosa. She received 4 grams per 24 hours, in accordance with the recommendations for the total daily dose during CVVH with an effluent flow rate of 2.1 to 3 L/h. We evaluated intraperitoneal, plasma arterial pre and post filter and ultrafiltrate (urine) total cefiderocol concentrations and discussed the pharmacokinetics in respect to the CVVH settings. The predicted unbound plasma concentrations during CI resulted in 6.8 to 9.5-fold higher concentrations than the adopted MIC of 2 mg/L for cefiderocol against Pseudomonas aeruginosa. The optimal 100% fT>MIC target of cefiderocol was met during the sampling period, suggesting adequate exposure during the total treatment period. The obtained intraperitoneal concentration indicated adequate cefiderocol exposure at the site of infection. Continuous infusion of 4 grams cefiderocol per 24 hours led to sufficient plasma concentrations in our anuric critically ill patient treated with CVVH. This case is supportive to the use of cefiderocol as continuous infusion.