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Updated: Apr 16, 2026

Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes
Published on: March 3, 2023
A statistical approach for determination of disk diffusion-based cutoff values for systematic characterization of
Giorgia Valsesia1, Malgorzata Roos2, Erik C Böttger1
1Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.
Abstract:
In this study, we introduce a new approach for determination of epidemiologic cutoffs (ECOFFs) and resistant-population cutoffs (RCOFFs) based on receiver operating characteristic (ROC) curves. As an example, the method was applied for determination of ECOFFs for seven different beta-lactam antibiotics and wild-type populations of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae. In addition, RCOFFs were determined for bacterial populations with defined resistance mechanisms ("resistotypes"), i.e., extended-spectrum beta-lactamase (ESBL)-positive E. coli, ESBL-positive K. pneumoniae, and ESBL-positive E. cloacae; AmpC cephalosporinase-positive E. coli and AmpC-positive K. pneumoniae; and broad-spectrum beta-lactamase (BSBL)-positive E. coli. RCOFFs and ECOFFs are instrumental for a systematic characterization of associations between resistotypes and wild-type populations.
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