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Indian Journal of Medical Microbiology
Medknow Publications on behalf of Indian Association of Medical Microbiology
ISSN: 0255-0857 EISSN: 0255-0857
Vol. 29, No. 3, 2011, pp. 297-301
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Bioline Code: mb11071
Full paper language: English
Document type: Research Article
Document available free of charge
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Indian Journal of Medical Microbiology, Vol. 29, No. 3, 2011, pp. 297-301
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Comparison of the boronic acid disk potentiation test and cefepime-clavulanic acid method for the detection of ESBL among AmpC-producing Enterobacteriaceae
Shoorashetty, R M.; Nagarathnamma, T & Prathibha, J
Abstract
Purpose: Extended spectrum β-lactamase (ESBL) and AmpC β-lactamase are important mechanisms of betalactam resistance among Enterobacteriaceae . The ESBL confirmation test described by Clinical Laboratory Standards Institute (CLSI) is in routine use. This method fails to detect ESBL in the presence of AmpC. Therefore, we compared two different ESBL detection methods against the CLSI confirmatory test. Materials and Methods: A total 200 consecutive clinical isolates of Enterobacteriaceae from various clinical samples were tested for ESBL production using (i) CLSI described phenotypic confirmatory test (PCT), (ii) boronic acid disk potentiation test and (iii) cefepime-CA disk potentiation method. AmpC confirmation was done by a modified three-dimensional test. Results: Among total 200 Enterobacteriaceae isolates, 82 were only ESBL producers, 12 were only AmpC producers, 55 were combined ESBL and AmpC producers, 14 were inducible AmpC producers and 37 isolates did not harboured any enzymes. The CLSI described PCT detected ESBL-producing organisms correctly but failed to detect 36.3% of ESBLs among combined enzyme producers. The boronic acid disk potentiation test reliably detected all ESBL, AmpC, and combined enzyme producers correctly. The cefepime-CA method detected all ESBLs correctly but another method of AmpC detection has to be adopted. Conclusion: The use of boronic acid in disk diffusion testing along with the CLSI described PCT enhances ESBL detection in the presence of AmpC betalactamases.
Keywords
AmpC β-lactamase, boronic acid, cefepime, Enterobacteriaceae, Extended spectrum β-lactamase
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© Copyright 2011 Indian Journal of Medical Microbiology. Alternative site location: http://www.ijmm.org
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