With the widespread clinical use of ceftazidime-avibactam (CZA), reports of resistance have increased continuously, posing immense threats to public health worldwide. In this study, we explored the underlying mechanisms leading to the development of CZA resistance in an ST11-KL64 hypervirulent Klebsiella pneumoniae CRE146 that harbored the bla gene. Twelve carbapenem-resistant Klebsiella pneumoniae (CRKP) strains were isolated from the same patient, including K. pneumoniae CRE146. Whole genome sequencing (WGS), phylogenetic analysis, bla gene cloning and pACYC-KPC construction assays were conducted to further explore the molecular mechanisms of CZA resistance. Quantitative siderophore production assay, string test, capsule quantification and Galleria mellonella in vivo infection model were applied to verify the level of pathogenicity of K. pneumoniae CRE146. This strain carried key virulence factors, iutA-iucABCD operon and rmpA gene. Compared to the wild-type KPC-2 carbapenemase, the novel KPC-228 enzyme exhibited a deletion of four amino acids in the Ω-loop (del_167-170_ELNS). In addition, the emergence of CZA resistance appeared to be associated with drug exposure, and we observed the in vivo evolution of wild-type KPC-2 to KPC-228 and then the reversion to its original wild-type KPC-2. The bla gene was located within the double IS26 flanking the ISKpn6-bla-ISKpn27 core structure and carried on an IncFII/IncR-type plasmid. Notably, CRE146 exhibited high-level resistance to CZA (64/4 mg/L) but increased susceptibility to meropenem (1 mg/L) and imipenem (0.5 mg/L) respectively. PACYC-KPC plasmids were constructed and expressed in K. pneumoniae ATCC13883. Compared to K. pneumoniae ATCC13883 harboring bla, K. pneumoniae ATCC13883 harboring bla exhibited a high-level resistance to CZA (32/4 mg/L) and increased susceptibility to meropenem (1 mg/L) and imipenem (0.5 mg/L). Interestingly, K. pneumoniae ATCC13883 harboring bla showed a significant decrease in their resistance to all β-lactamases tested except CZA and ceftazidime. In conclusion, we reported a novel KPC variant, KPC-228, in a clinical ST11-KL64 hypervirulent K. pneumoniae strain, which conferred CZA resistance, possibly through enhancing ceftazidime affinity and reducing avibactam binding. The bla can mutate back to bla under carbapenem pressure, which was very detrimental to clinical treatment. This strain carried both resistance and virulence genes, posing a major challenge in clinical management.
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http://dx.doi.org/10.1016/j.ijantimicag.2024.107411 | DOI Listing |
Int J Antimicrob Agents
December 2024
Department of Clinical Laboratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China. Electronic address:
Eur J Clin Microbiol Infect Dis
December 2024
Medical and Molecular Microbiology Unit, Department of Medicine, Faculty of Science and Medicine, University of Fribourg, Chemin du Musée 18, Fribourg, CH-1700, Switzerland.
To evaluate the in-vitro activity of the novel commercially-available drugs, including meropenem-vaborbactam (MEV), ceftazidime-avibactam (CZA), ceftolozane-tazobactam (C/T), imipenem-relebactam (IPR) as well as cefiderocol (FDC), against carbapenem-resistant Pseudomonas spp. (CRP) isolates. All CRP isolates collected at the Swiss National Reference Laboratory (NARA) over the year 2022 (n = 170) have been included.
View Article and Find Full Text PDFActa Microbiol Immunol Hung
December 2024
2Department of Medical Microbiology, Hamidiye Medical Faculty, University of Health Sciences, Istanbul, Turkey.
Treatment options are limited for infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates due to the production of metallo-β-lactamase (MBL). The ceftazidime-avibactam (CZA)/ aztreonam (ATM) combination represents a new therapeutic approach in MBL-positive isolates. Our study aims to determine distribution of carbapenemase genes in CRKP isolates and to investigate the in vitro synergistic effect of the CZA/ATM combination.
View Article and Find Full Text PDFInfect Drug Resist
December 2024
Division of Infectious Disease, Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan.
Purpose: Ceftazidime-avibactam (CZA), a novel beta-lactam/beta-lactamase inhibitor, plays an important role in the threat of emerging carbapenem-resistant Enterobacterales (CRE) infection. The study aims to analyze the clinical effectiveness and factors influencing treatment response to CZA for carbapenem-resistant (CRKP) infections.
Patients And Methods: From February 2020 to December 2021, patients with CRKP infection treated with CZA were enrolled in this retrospective, single-center cohort study in northern Taiwan.
Eur J Clin Microbiol Infect Dis
November 2024
Faculdade de Ciências Farmacêuticas de Ribeirão Preto - Universidade de São Paulo, Ribeirão Preto, Brazil.
Purpose: Tolerance and persistence occur "silently" in bacteria categorized as susceptible by antimicrobial susceptibility testing in clinical microbiology laboratories. They are different from resistance phenomena, not well-studied, and often remain unnoticeable. We aimed to investigate and characterize ceftazidime-avibactam (CZA) tolerance/persistence in 80 Klebsiella pneumoniae isolates from bloodstream infections.
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