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KMID : 0829320090120010024
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Korean Journal of Clinical Microbiology
2009 Volume.12 No. 1 p.24 ~ p.29
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Use of Boronic Acid Disks for the Detection of Extended-spectrum β-lactamase and AmpC β-lactamase in Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca and Proteus mirabilis
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Park Soon-Deok
Uh Young
Kwon Oh-Gun
Yoon Kap-Jun
Kim Hyo-Youl
Jang In-Ho
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Abstract
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Background: Accurate detection of organisms producing extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase is very important for treatment of patients. However, unlike the ESBL confirmatory test, there are no guidelines for detection of organisms producing AmpC β-lactamase. We evaluated a detection method using boronic acid (BA) for ESBL and AmpC β-lactamase.
Methods: Clinical isolates of Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, and Proteus mirabilis showing intermediate resistance or resistance to cefoxitin (FOX) or positive for ESBL were tested. A ≥5 mm increase in zone diameter of ceftazidime/clavulanic acid/BA (CAZ/CA/BA) and/or cefotaxime/clavulanic acid/BA (CTX/CA/BA) versus CAZ/BA and/or CTX /BA was considered positive for ESBL. Likewise, a ≥5 mm increase in zone diameter of FOX/BA and/or cefotetan/BA (CTT/BA) versus FOX and/or CTT alone was considered positive for AmpC β-lactamase.
Results: Among 622 clinical isolates, ESBL positive rates by the CLSI ESBL confirmatory test or by the BA method were 18.1% or 18.4% for E. coli, 38.3% or 40.4% for K. pneumoniae, 8.7%or 8.7% for K. oxytoca, and 14.8% or 14.8% for P. mirabilis, respectively. AmpC β-lactamase positive rates using the BA method were 3.7% for E. coli, 33.3% for K. pneumoniae, 0% for K. oxytoca, and 7.4% for P. mirabilis. The detection rates of coproducing ESBL and AmpC β-lactamase were 2.4% in E. coli 27.1% in K. pneumoniae, and 3.7% in P. mirabilis.
Conclusion: The ESBL confirmatory method using BA was found to enhance the detection of ESBLs, even when potentially masked by AmpC β-lactamase
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KEYWORD
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Extended-spectrum β-lactamase, Plasmidmediated AmpC β-lactamase, Boronic acid, Coproducers
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