New method for laboratory detection of AmpC beta-lactamases in Escherichia coli and Klebsiella pneumoniae.
A new cefoxitin-agar medium (CAM)-based assay was compared to the previously published modified three-dimensional (M3D) assay for the detection of AmpC production in Escherichia coli and Klebsiella pneumoniae. Clinical isolates of cefoxitin-resistant E. coli (n = 5) and K. pneumoniae (n = 7) and multiple control strains with and without AmpC enzymes were tested by both methods. The CAM method with 4 microg of cefoxitin/ml was equivalent to the M3D method for detecting AmpC production in E. coli and K. pneumoniae. This new method is easier to perform and interpret and allows for testing of multiple isolates on a single plate.
Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada.
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Pitout
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Conly
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Church
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Gregson
D000362:Agar; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism*; D002440:Cefoxitin / Q000494:pharmacology*; D003470:Culture Media; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology*; D008826:Microbial Sensitivity Tests; D012680:Sensitivity and Specificity; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D003470:Culture Media; D002440:Cefoxitin; D000362:Agar; C048795:AmpC beta-lactamases; D001618:beta-Lactamases