Rapid detection of plasmid-mediated AmpC-producers by eazyplex® SuperBug AmpC assay compared to whole-genome sequencing

Vladimira Hinić; Helena M B Seth-Smith; Sabrina Stammler; Adrian Egli

doi:10.1016/j.mimet.2024.106938

Rapid detection of plasmid-mediated AmpC-producers by eazyplex® SuperBug AmpC assay compared to whole-genome sequencing

J Microbiol Methods. 2024 Apr 19:221:106938. doi: 10.1016/j.mimet.2024.106938. Online ahead of print.

Authors

Vladimira Hinić¹, Helena M B Seth-Smith², Sabrina Stammler³, Adrian Egli²

Affiliations

¹ Division of Clinical Bacteriology and Mycology, University Hospital Basel, Basel, Switzerland; Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland. Electronic address: vhinic@imm.uzh.ch.
² Division of Clinical Bacteriology and Mycology, University Hospital Basel, Basel, Switzerland; Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland; Applied Microbiology Research, Department of Biomedicine, University of Basel, Basel, Switzerland.
³ Division of Clinical Bacteriology and Mycology, University Hospital Basel, Basel, Switzerland.

PMID: 38642781
DOI: 10.1016/j.mimet.2024.106938

Abstract

Current methods for plasmid-mediated AmpC β-lactamase (pAmpC) detection in routine microbiological laboratories are based on various phenotypic tests. Eazyplex®SuperBug AmpC assay is a molecular assay based on isothermal amplification for rapid detection of the most common pAmpC types from bacterial culture: CMY-2 group, DHA, ACC and MOX. Our aim was to evaluate the diagnostic performance of this assay. The assay was evaluated on 64 clinical isolates of Enterobacterales without chromosomal inducible AmpC, and with phenotypically confirmed AmpC production. The results were confirmed, and isolates further characterized by whole-genome sequencing (WGS). eazyplex®SuperBug AmpC assay correctly detected the two most common pAmpC types CMY-2 group (16/16) and DHA (19/19). Detection of ACC and MOX could not be evaluated on our set of isolates since there was only one isolate harbouring ACC and none with MOX. pAmpC encoding genes could be detected in only eight of 36 investigated Escherichia coli isolates. The remaining 28 E. coli isolates harboured previously described mutations in the bla_EC promoter, leading to the overexpression of chromosomally encoded E. coli specific AmpC β-lactamase. All results were 100% concordant with the results of WGS. eazyplex®SuperBug AmpC assay enabled rapid and reliable detection of pAmpC-encoding genes in Enterobacterales like Klebsiella spp. and Proteus spp. and the distinction between plasmid-mediated and chromosomally encoded AmpC in E. coli.

Keywords: Eazyplex® SuperBug AmpC; Enterobacterales; Plasmid-mediated AmpC (pAmpC); Whole-genome sequencing (WGS).