Korean J Clin Microbiol.  2009 Mar;12(1):24-29. 10.5145/KJCM.2009.12.1.24.

Use of Boronic Acid Disks for the Detection of Extended-spectrum beta-lactamase and AmpC beta-lactamase in Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca and Proteus mirabilis

• Park SD
• Uh Y
• Jang IH
• Kwon O
• Yoon KJ
• Kim HY

• KMID: 1469966
• DOI: http://doi.org/10.5145/KJCM.2009.12.1.24

Abstract

BACKGROUND
Accurate detection of organisms producing extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase is very important for treatment of patients. However, unlike the ESBL confirmatory test, there are no guidelines for detection of organisms producing AmpC beta-lactamase. We evaluated a detection method using boronic acid (BA) for ESBL and AmpC beta-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 > or =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 > or =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 beta-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 beta-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 beta-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 beta-lactamase.

Keyword

Extended-spectrum beta-lactamase; Plasmid- mediated AmpC beta-lactamase; Boronic acid; Coproducers

MeSH Terms

Bacterial Proteins
beta-Lactamases
Boron
Cefoxitin
Escherichia
Escherichia coli
Humans
Klebsiella
Klebsiella oxytoca
Klebsiella pneumoniae
Masks
Mirabilis
Penicillinase
Pneumonia
Proteus
Proteus mirabilis
Bacterial Proteins
Boron
Cefoxitin
Penicillinase
beta-Lactamases