Case Report on Cefiderocol-Non-Susceptible Escherichia Coli in the Absence of Carbapenemase Genes

Objectives: Cefiderocol is a relatively newer cephalosporin often a last line combat multidrug-resistant Gram-negative bacterium, especially carbapenem-resistant Enterobacterales (CRE).However, resistance has already been observed in several countries despite the recent years of clinical treatment.Methods: Here we report a fatal case of carbapenem-resistant Escherichia coli with cefiderocol non-susceptibility isolated from an intra-abdomen surgical specimen of a renal transplant patient.This isolate was characterized using whole genome sequencing to assess for underlying resistant genes contributing to cefiderocol resistance. Results:We have identified resistant genes putatively related to cefiderocol non-susceptibility and other antibiotic resistance including carbapenems.In comparison with current literature, several genes may be novel in the context of cefiderocol resistance in a carbapenem-resistant E.coli. Conclusions:Genes related to cefiderocol resistance identified in this isolate include variants of iron-uptake genes (cirA, fepA, fepB, fepG, tonB), porin uptake genes (ftsI, fecB), and RNA polymerase gene (pcnB).