Klebsiella pneumoniae carbapenemase (KPC) producer resistant to ceftazidime–avibactam due to a deletion in the blaKPC3 gene

Abstract

Objectives: Carbapenemase-producing strains of Klebsiella pneumoniae (KPC) are a great health concern, and therapy with ceftazidimeeavibactam represents a choice for the treatment of infections involving these strains. We report a strain resistant to ceftazidimeeavibactam due to a deletion of six nucleotides in the bla KPC gene sequence. Methods: Two strains, namely AMP920 and AMP2009, were isolated from the same patient a month apart. Antimicrobial susceptibility testing was performed both by broth microdilution and by Etest. Immunoenzymatic assay to detect carbapenemase was performed for both strains. The bla KPC gene of both strains was amplified by PCR and sequenced. Enzyme activity towards carbapenems was tested by the CarbaNP test and hydrolysis spectrophotometer assay. Results: The two isolates differed in antimicrobial susceptibility. AMP920 showed meropenem and imipenem resistance (MIC 32 and 32 mg/mL). A month later the carbapenem MIC decreased to 8 and 1 mg/mL respectively, while the ceftazidimeeavibactam MIC increased from 1 to 16 mg/mL. Both isolates showed a positive immunoenzymatic test for the KPC enzyme, but only AMP920 showed a positive CarbaNP test hydrolysing imipenem. The Bla KPC gene was amplified in both strains. After sequencing, the two amplicons showed a KPC3 variant. The gene of the second isolate showed a deletion of six nucleotides at 498e503, resulting in a mutant variant with the deletion of glutamic acid and leucine residues at positions 167 and 168. Conclusions: We detected a new deletion in the bla KPC gene of a clinical strain of K. pneumoniae which resulted in resistance to ceftazidimeeavibactam. The amino acids deleted are in the U loop (amino acids 165e179) of the KPC enzyme, enhancing ceftazidime affinity and preventing avibactam binding.

Emergence of a KPC Variant Conferring Resistance to Ceftazidime-Avibactam in a Widespread ST11 Carbapenem-Resistant Klebsiella pneumoniae Clone in China

“…Notably, amino acid substitutions, such as KPC-8 (Val240Gly and His274Tyr) (Gregory et al, 2010) and (Galani et al, 2019), occurred outside the omega-loop region of KPC, but resistance to CZA has also been reported. In addition, a recent study found that CZA resistance in K. pneumoniae was involved in amino acid deletion at different positions of , indicating that amino acid deletion of the KPC protein could be associated with CZA resistance (Antinori et al, 2020).…”

Emergence of Ceftazidime/Avibactam and Tigecycline Resistance in Carbapenem-Resistant Klebsiella pneumoniae Due to In-Host Microevolution

“…CZA resistance caused by KPC point mutations tends to occur after the strains are exposed to CZA either in vivo or in vitro ( Livermore et al., 2015b ; Barnes et al, 2017 ; Shields et al., 2017 ). Additionally, Antinori E. reported that deletion in bla KPC-3 in clinical K. pneumoniae could also result in CZA resistance ( Antinori et al., 2020 ). In our study, the CZA-resistant strain evolved double copies of bla KPC-2 compared with the index strains.…”

Performance Evaluation of the Gradient Diffusion Strip Method and Disk Diffusion Method for Ceftazidime–Avibactam Against Enterobacterales and Pseudomonas aeruginosa: A Dual-Center Study

“…In the 31 bla KPC -positive Enterobacterales isolates, 30 were susceptible to ceftazidime–avibactam, in addition to Klebsiella oxytoca that bla KPC coupled with bla NDM positive. However, there have been some reports of bla KPC -positive Klebsiella pneumoniae resistance to ceftazidime–avibactam in recent years ( Gottig et al, 2019 ; Antinori et al, 2020 ). In the 32 bla NDM -positive Enterobacterales isolates, only one Escherichia coli isolated from a rectal swab of a newborn was susceptible to ceftazidime–avibactam; the others were all resistant.…”