Cefoxitin-Serum Creatinine Interference in a Patient With Nontuberculous Ventriculomeningitis.

Cefoxitin is a second-generation cephamycin antibiotic, which at concentrations ≥100 µg/mL is known to modestly interfere, for up to 2 hours post-infusion, with serum creatinine measurement via the traditional Jaffe-based assay. We report a case of a severe serum creatinine elevation while utilizing cefoxitin as a component of an antimicrobial regimen in a critically ill patient with ventriculomeningitis. Our results, both via patient serum analysis and a cefoxitin spiking experiment, demonstrate interference despite the utilization of improved modern Jaffe-based assays.