Assessment of Activity and Resistance Mechanisms to Cefepime in Combination with the Novel β-Lactamase Inhibitors Zidebactam, Taniborbactam, and Enmetazobactam against a Multicenter Collection of Carbapenemase-Producing Enterobacterales

The global distribution of carbapenemases such as KPC, OXA-48, and metallo-beta-lactamases (MBLs) gives cause for concern, as these enzymes are not inhibited by classical beta-lactamase inhibitors (BLIs). The current development of new inhibitors is one of the most promising highlights for the treatment of multidrug-resistant bacteria. The activity of cefepime in combination with the novel BLIs zidebactam, taniborbactam, and enmetazobactam was studied in a collection of 400 carbapenemase-producing Enterobacterales (CPE). The genomes were fully sequenced and potential mechanisms of resistance to cefepime/BLI combinations were characterized. Cefepime resistance in the whole set of isolates was 79.5% (MIC50/90 64/>= 128mg/L). The cefepime/zidebactam and cefepime/taniborbactam combinations showed the highest activity (MIC50/90 <= 0.5/1 and <= 0.5/2 mg/L, respectively). Cefepime/zidebactam displayed high activity, regardless of the carbapenemase or extended-spectrum beta-lactamase (ESBL) considered (99% of isolates displayed MIC <= 2 mg/L). Cefepime/taniborbactam displayed excellent activity against OXA-48- and KPC-producing Enterobacterales and lower activity against MBL-producing isolates (four strains yielded MICs >= 16 mg/L: 2 NDM producers with an insertion in PBP3, one VIM-1 producer with nonfunctional OmpK35, and one IMP-8 producer). Cefepime/enmetazobactam displayed the lowest activity (MIC50/90 1/>= 128 mg/L), with MICs >= 16 mg/L for 49 MBL producers, 40 OXA-48 producers (13 with amino acid changes in OmpK35/36, 4 in PBPs and 11 in RamR) and 25 KPC producers (most with an insertion in OmpK36). These results confirm the therapeutic potential of the new beta-lactamase inhibitors, shedding light on the activity of cefepime and BLIs against CPE and resistance mechanisms. The cefepime/zidebactam and cefepime/taniborbactam combinations are particularly highlighted as promising alternatives to penicillin-based inhibitors for the treatment of CPE.

Automated summary

The global distribution of carbapenemases is a concern due to their resistance to traditional beta-lactamase inhibitors. The development of new inhibitors shows promise in treating multidrug-resistant bacteria. The combination of cefepime with novel beta-lactamase inhibitors, zidebactam, taniborbactam, and enmetazobactam, demonstrated high activity against carbapenemase-producing Enterobacterales, particularly cefepime/zidebactam and cefepime/taniborbactam.