Objectives: the aim of this study was to investigate the prevalence of ceftazidime/avibactam (CZA) resistance among carbapenemase-producing Enterobacterales (CPE) blood culture isolates as well as the performance of the main carbapenemase phenotypic detection methods to identify KPC variants associated with CZA resistance. Methods: non-duplicate CPE strains isolated from blood cultures during 2018–2020 were tested for antimicrobial susceptibility. Molecular testing was used to identify carbapenemase-producers. Strains harbouring blaKPC and with a CZA minimum inhibitory concentration (MIC) ≥8 mg/L were investigated by sequencing. Subsequentially, five phenotypic carbapenemase detection methods were evaluated on these strains, namely the modified carbapenem inactivation method (mCIM), Rapidec® Carba NP, the disk diffusion synergy test, NG-Test CARBA® 5 and RESIST-5 O.O.K.N.V. Results: overall, the CZA resistance rate was high (13.7%) and remained relevant (5.9%) excluding metallo-β-lactamases-producers. All isolates harbouringblaKPC mutants (n = 8) were associated with reduced carbapenem MICs and negative results by all detection methods based on revelation of enzyme activity. Lateral flow immunoassays failed to detect KPC-31 (n = 4) and KPC-33 (n = 2) but correctly identified KPC-14 (n = 2). Conversely, isolates harbouring wild-type KPC genes (n = 3) were associated with high-level CZA resistance and carbapenem resistance and tested positive by all of the evaluated methods. Conclusion: in the era of CZA-based therapies, molecular blaKPC identification followed by a carbapenem hydrolysis-based phenotypic assay could be the most reasonable diagnostic algorithm to detect all KPC-producers and to identify mutants associated with impaired carbapenemase activity and CZA resistance.

Carbapenemase detection testing in the era of ceftazidime/avibactam-resistant KPC-producing Enterobacterales: A 2-year experience.

Gabriele Bianco
First
;
Matteo Boattini;Marco Iannaccone;Alessandro Bondi;Davide Ghibaudo;Elisa Zanotto;Marco Peradotto;Rossana Cavallo;Cristina Costa
Last
2021-01-01

Abstract

Objectives: the aim of this study was to investigate the prevalence of ceftazidime/avibactam (CZA) resistance among carbapenemase-producing Enterobacterales (CPE) blood culture isolates as well as the performance of the main carbapenemase phenotypic detection methods to identify KPC variants associated with CZA resistance. Methods: non-duplicate CPE strains isolated from blood cultures during 2018–2020 were tested for antimicrobial susceptibility. Molecular testing was used to identify carbapenemase-producers. Strains harbouring blaKPC and with a CZA minimum inhibitory concentration (MIC) ≥8 mg/L were investigated by sequencing. Subsequentially, five phenotypic carbapenemase detection methods were evaluated on these strains, namely the modified carbapenem inactivation method (mCIM), Rapidec® Carba NP, the disk diffusion synergy test, NG-Test CARBA® 5 and RESIST-5 O.O.K.N.V. Results: overall, the CZA resistance rate was high (13.7%) and remained relevant (5.9%) excluding metallo-β-lactamases-producers. All isolates harbouringblaKPC mutants (n = 8) were associated with reduced carbapenem MICs and negative results by all detection methods based on revelation of enzyme activity. Lateral flow immunoassays failed to detect KPC-31 (n = 4) and KPC-33 (n = 2) but correctly identified KPC-14 (n = 2). Conversely, isolates harbouring wild-type KPC genes (n = 3) were associated with high-level CZA resistance and carbapenem resistance and tested positive by all of the evaluated methods. Conclusion: in the era of CZA-based therapies, molecular blaKPC identification followed by a carbapenem hydrolysis-based phenotypic assay could be the most reasonable diagnostic algorithm to detect all KPC-producers and to identify mutants associated with impaired carbapenemase activity and CZA resistance.
2021
24
411
414
Gabriele Bianco, Matteo Boattini, Marco Iannaccone, Alessandro Bondi, Davide Ghibaudo, Elisa Zanotto, Marco Peradotto, Rossana Cavallo, Cristina Costa...espandi
File in questo prodotto:
File Dimensione Formato  
Carbapenemase detection testing in the era of ceftazidime avibactam-resistant KPC-producing Enterobacterales A 2-year experience.pdf

Accesso aperto

Tipo di file: PDF EDITORIALE
Dimensione 273.05 kB
Formato Adobe PDF
273.05 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1840523
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 31
  • ???jsp.display-item.citation.isi??? 27
social impact