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KPC-Mediated Resistance to Ceftazidime-Avibactam and Collateral Effects in Klebsiella pneumoniae
Jacqueline Findlay1, Laurent Poirel1,2,3, Mario Juhas1
1Emerging Antibiotic Resistance Unit, Medical and Molecular Microbiology, Faculty of Science and Medicine, University of Fribourggrid.8534.a, Fribourg, Switzerland.
Abstract:
Carbapenem-resistant Enterobacterales, such as Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae, represent a major threat to public health due to their rapid spread. Novel drug combinations such as ceftazidime-avibactam (CZA), combining a broad-spectrum cephalosporin along with a broad-spectrum β-lactamase inhibitor, have recently been introduced and have been shown to exhibit excellent activity toward multidrug-resistant KPC-producing Enterobacterales strains. However, CZA-resistant K. pneumoniae isolates are now being increasingly reported, mostly corresponding to producers of KPC variants. In this study, we evaluated in vitro the nature of the mutations in the KPC-2 and KPC-3 β-lactamase sequences (the most frequent KPC-type enzymes) that lead to CZA resistance and the subsequent effects of these mutations on susceptibility to other β-lactam antibiotics. Single-step in vitro selection assays were conducted, resulting in the identification of a series of mutations in the KPC sequence which conferred the ability of those mutated enzymes to confer resistance to CZA. Hence, 16 KPC-2 variants and 10 KPC-3 variants were obtained. Production of the KPC variants in an Escherichia coli recombinant strain resulted in a concomitant increased susceptibility to broad-spectrum cephalosporins and carbapenems, with the exceptions of ceftazidime and piperacillin-tazobactam, compared to wild-type KPC enzymes. Enzymatic assays showed that all of the KPC variants identified exhibited an increased affinity toward ceftazidime and a slightly decreased sensitivity to avibactam, sustaining their impact on CZA resistance. However, their respective carbapenemase activities were concurrently negatively impacted.
Insights
New mutations in carbapenemase genes (KPC-2 and KPC-3) cause resistance to ceftazidime-avibactam (CZA) in Klebsiella pneumoniae. These KPC variants show altered susceptibility to other antibiotics, impacting treatment options.
Area of Science:
- Microbiology
- Infectious Diseases
- Drug Resistance
Background:
- Carbapenem-resistant Enterobacterales (CRE), particularly Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae, pose a significant public health threat.
- Ceftazidime-avibactam (CZA) is a novel therapeutic option against multidrug-resistant KPC-producing Enterobacterales.
- Emerging CZA resistance in K. pneumoniae, often linked to KPC variants, necessitates understanding resistance mechanisms.
Purpose of the Study:
- To investigate the specific mutations in KPC-2 and KPC-3 beta-lactamase sequences that confer resistance to CZA.
- To determine the impact of these mutations on the susceptibility of K. pneumoniae to other beta-lactam antibiotics.
- To elucidate the enzymatic basis for CZA resistance in KPC variants.
Main Methods:
- In vitro single-step selection assays were employed to generate CZA-resistant KPC variants.
- Mutated KPC-2 and KPC-3 sequences were introduced into an Escherichia coli recombinant strain for analysis.
- Enzymatic assays were performed to assess the activity of KPC variants against CZA and other beta-lactam antibiotics.
Main Results:
- Sixteen KPC-2 variants and ten KPC-3 variants conferring CZA resistance were identified.
- KPC variants exhibited increased susceptibility to broad-spectrum cephalosporins and carbapenems, excluding ceftazidime and piperacillin-tazobactam.
- Enzymatic assays confirmed increased affinity for ceftazidime and reduced avibactam sensitivity in KPC variants, while carbapenemase activity was diminished.
Conclusions:
- Mutations in KPC-2 and KPC-3 enzymes are responsible for CZA resistance in K. pneumoniae.
- These KPC variants display altered susceptibility profiles, potentially impacting therapeutic strategies.
- Understanding these resistance mechanisms is crucial for managing infections caused by CZA-resistant K. pneumoniae.
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