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bioRxiv · 10.1101/2024.10.11.617870

Cefepime-Taniborbactam and Ceftibuten-Ledaborbactam Maintain Activity Against KPC Variants that Lead to Ceftazidime-Avibactam Resistance

Myers, C. L.·Stevenson, A.·Miller, B.·Daigle, D. M.·Uehara, T.·Pevear, D. C.
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Abstract

Klebsiella pneumoniae carbapenemases (KPCs) are widespread {beta}-lactamases that are a major cause of clinical non-susceptibility of Gram-negative bacteria to carbapenems and other {beta}-lactam antibiotics. Ceftazidime combined with the {beta}-lactamase inhibitor avibactam (CAZ-AVI) has been effective for treating infections by KPC-producing bacteria, but emergent KPC variants confer resistance to the combination. Taniborbactam and ledaborbactam are bicyclic boronate {beta}-lactamase inhibitors under development with cefepime and ceftibuten, respectively, to treat carbapenem-resistant bacterial infections. Here, we assessed the effects of clinically important KPC-2 and KPC-3 variants (V240G, D179Y, D179Y T243M) on the antibacterial activity of cefepime-taniborbactam (FEP-TAN) and ceftibuten-ledaborbactam (CTB-LED) and examined catalytic activity and inhibition of these variants. FEP-TAN and CTB-LED were highly active against CAZ-AVI-resistant engineered E. coli strains expressing these variants. Purified KPC variants catalyzed more efficient CAZ hydrolysis than wild-type enzymes, and D179Y-containing KPC-3 variants additionally catalyzed more efficient FEP hydrolysis than wild-type KPC-3. All KPC variants poorly hydrolyzed CTB, and D179Y-containing variants demonstrated significantly higher affinity for CAZ than FEP or CTB. Second-order rate constants (k2/K) for inhibition of D179Y-containing KPC-2 variants were significantly reduced relative to wild-type KPC-2, with AVI most impacted. K2/K was less affected for D179Y-containing KPC-3 variants, and reflected robust inhibition by TAN, LED and AVI. Together, the findings illustrate a biochemical basis for greater FEP-TAN and CTB-LED antibacterial activity in KPC variant expression backgrounds relative to CAZ-AVI, whereby the boronate inhibitors have sufficient inhibitory activity, whilst FEP and CTB are poorer substrates and bind to the variant enzymes with reduced affinity compared to CAZ.

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Myers, C. L., Stevenson, A., Miller, B., Daigle, D. M., Uehara, T., Pevear, D. C.. 2024-10-11. Cefepime-Taniborbactam and Ceftibuten-Ledaborbactam Maintain Activity Against KPC Variants that Lead to Ceftazidime-Avibactam Resistance. https://doi.org/10.1101/2024.10.11.617870

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