Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology

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pISSN 2288-0585 eISSN 2288-6850

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

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2009 March, Volume 12, Issue 1, pages 24-29.

https://doi.org/10.5145/ACM.2009.12.1.24

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

Soon Deok Park1, Young Uh1, In Ho Jang1, Ohgun Kwon1, Kap Jun Yoon1, Hyo Youl Kim2
Departments of 1Laboratory Medicine and 2Infectious Diseases, Yonsei University Wonju College of Medicine, Wonju, Korea

Abstract

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. (Korean J Clin Microbiol 2009;12:24-29)

Keywords

Extended-spectrum β-lactamase, Plasmid- mediated AmpC β-lactamase, Boronic acid, Coproducers