Phenotypic detection of β-lactamase-mediated resistance to oxyimino-cephalosporins in Enterobacteriaceae: evaluation of the Mastascan Elite Expert System

Objectives: The aim of this study was to evaluate phenotypic detection of β-lactamase-mediated resistance to oxyimino-cephalosporins in Enterobacteriaceae using the Mastascan Elite Expert System challenged with a battery of genotypically characterized organisms. Methods: Isolates (n = 120) were iden...

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Bibliographic Details
Published in:Journal of antimicrobial chemotherapy 2005-08, Vol.56 (2), p.292-296, Article 292
Main Authors: Winstanley, T. G., Parsons, H. K., Horstkotte, M. A., Sobottka, I., Stürenburg, E.
Format: Article
Language:English
Subjects:
AmpC
Antibiotics. Antiinfectious agents. Antiparasitic agents
beta-Lactam Resistance - genetics
beta-Lactamases - drug effects
beta-Lactamases - genetics
Biological and medical sciences
Cephalosporins - pharmacology
CTX-M
Enterobacteriaceae
Enterobacteriaceae - drug effects
Enterobacteriaceae - enzymology
Enterobacteriaceae - genetics
ESBLs
expert system
interpretative reading
Medical sciences
Microbial Sensitivity Tests
Pharmacology. Drug treatments
Phenotype
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Summary:Objectives: The aim of this study was to evaluate phenotypic detection of β-lactamase-mediated resistance to oxyimino-cephalosporins in Enterobacteriaceae using the Mastascan Elite Expert System challenged with a battery of genotypically characterized organisms. Methods: Isolates (n = 120) were identified to species level and antimicrobial susceptibilities were determined using agar incorporation methods and Mastascan Elite. Phenotypes were examined using an Expert System (ES) and putative genotypes were suggested using interpretative reading. Results: Identification was correct in 119 of 120 isolates. The ES was able to identify the correct β-lactam phenotype (as deduced from molecular methods) in a single choice in 98 of 120 (81.7%) isolates. In an additional 15 (12.5%) cases, the ES identified the correct β-lactam phenotype within two or more choices. The detected phenotype was incorrect in seven (5.8%) isolates, but three of these were not inherent to the ES. Conclusions: The Mastascan Elite ES is relatively inexpensive and flexible and can identify the mechanism of resistance to oxyimino-cephalosporins in the majority of Enterobacteriaceae without recourse to molecular methods.
ISSN:0305-7453
1460-2091
DOI:10.1093/jac/dki203