Insights Into The Activity Of Cefiderocol Against PER-2 B-lactamase Producing Enterobacterales

M. RUGGIERO; MUÑOZ, JACKSON IVAN BRICEÑO; G. GUTKIND; R. A. BONOMO; P. POWER

Houston

Congreso; ASM Microbe 2023; 2023

American Society for Microbiology

Cefiderocol (FDC) is a novel chlorocatechol-cephem antibiotic indicated for the treatment of Gram-negative infections including multidrug resistant (MDR). The catechol group at 3- position facilitates entry to the bacterial cell via iron uptake mechanisms. PER ESBLs are primarily found in Enterobacterales and non-fermenters. PER are structurally unique as they possess an inverted Ω-loop and an expanded β3-β4 loop that result in a larger active site cavity. In this study, the activity of FDC against PER-2 producing Enterobacterales isolates was evaluated, and in silico models predicting structural-biochemical behavior are proposed.MICs of FDC were determined for 20 PER-producing strains, derived E. coli transformants andrecombinant E. coli clones producing PER-2 mutants in R220 or T237, using iron-depleted cation adjusted Mueller Hinton broth. Steady-state kinetics for FDC against PER-2 was performed. In silico modeling of the non-covalent (Michaelis) and covalent (acyl-enzyme) complex of PER-2 and FDC were obtained. MIC ranged between 0.25-8 µg/ml for most isolates and transformants, except for 2 strains (E. coli I23, 32 µg/ml; E. cloacae C18, >64 µm/ml). In recombinant clones overexpressing PER-2, MIC values decreased up to 11 dilutions (512 to 0.125 µg/ml). Catalytic efficiency for PER-2 was 0.072 µM -1 s -1 , similar to that for PER-1 (0.046 µM -1 s -1 ). In silico models reveal that FDC can accommodate within the PER-2 active site as two energetically favorable conformers (C1 and C2). Similar interactions are observed in both the Michaelis complex and the acyl-enzymes for both conformers and residues Q69, S70, K73, S130, N,132, E166, H170, R220, T235, and T237. Unique interactions are predicted between: (i) the chloro-dihydroxybenzoyl moiety and S238, T241 and E272 (C1; Figure 1) and Q219 and E276 (C2); (ii) the ceftazidime’s carboxypropan moiety and Q69 and G239 (C1), and M169 (C2).FDC seems to be active on most of the PER-2-producing Enterobacterales tested, as well as derived transformant clones. Remarkably, variants at either R220 and T237 seem to strongly affect the hydrolysis of FDC, supporting previous data about the structural and functional importance of these residues in this ESBL. Unique structural features of PER enzymes seem to favor the interaction with the bulky molecule of FDC. Discrepancies between the MIC and kinetic/structural data likely indicate that additional mechanisms and different expression levels are involved in different strains.