Repeated insertions at positions 261-280 in KPC-2 highlight a ceftazidime-avibactam resistance hotspot

Area of Science:

• Microbiology
• Molecular Biology
• Drug Resistance

Background:

• The rise of antibiotic resistance poses a significant threat to public health.
• Beta-lactamase enzymes, particularly Klebsiella pneumoniae carbapenemase (KPC), are key drivers of resistance to beta-lactam antibiotics.
• Ceftazidime-avibactam (CZA) is a crucial antibiotic for treating infections caused by multidrug-resistant Gram-negative bacteria.

Purpose of the Study:

• To characterize a novel KPC variant, KPC-261, identified in a Klebsiella pneumoniae strain.
• To investigate the molecular mechanism underlying high-level resistance to ceftazidime-avibactam (CZA) conferred by KPC-261.
• To understand the evolutionary pathways of beta-lactamase enzymes.

Main Methods:

• Isolation and identification of Klebsiella pneumoniae strains.
• Antimicrobial susceptibility testing, including resistance profiling against CZA.
• Comparative sequence analysis of the KPC-261 variant.
• Structural analysis to elucidate the impact of mutations on avibactam binding.

Main Results:

• Identification of KPC-261, a novel KPC variant in Klebsiella pneumoniae.
• Demonstration of high-level resistance to CZA in the identified strain.
• Discovery of a repeated insertion event between amino acid positions 261-280 in KPC-261.
• Identification of a mutational hotspot associated with reduced avibactam binding.

Conclusions:

• KPC-261 represents a new mechanism of CZA resistance in Klebsiella pneumoniae.
• The identified insertion mutation provides a structural basis for reduced avibactam binding.
• This study enhances our understanding of beta-lactamase evolution and the mechanisms of antibiotic resistance.