Evaluation of five commercially available rapid ESBL detection methods in a routine clinical microbiology laboratory

Abstract number: 1732_197

Lo-Ten-Foe J., Hendriks-Franssen M., Buiting A.

Objectives: We evaluated five commercially available easy-to-perform phenotypic tests designed for ESBL detection in our routine clinical microbiology laboratory.

Methods: We compared the E-test (Biotest), two different disk diffusion systems (supplied by Becton Dickinson and Oxoid), VITEK 2 susceptibility testing cards (AST-N020, AST-N048) lacking an ESBL test in combination with the Advanced Expert System (bioMérieux), and VITEK 2 susceptibility testing cards (AST-N041, EXT-N04) containing an ESBL test (bioMérieux). Both clinical isolates (Escherichia coli and Klebsiella species) from our laboratory and genotypically characterised ESBL-producing isolates were tested using the different phenotypic testing methods.

Results: A high sensitivity (87.5–100%) was observed for all tested phenotypic ESBL detection methods in the clinical isolates and in the genotypically characterised ESBL-producing isolates. The specificity for the two disk diffusion systems, E-test and VITEK 2 susceptibility testing cards containing an ESBL test was also high (80–100%). However, the specificity for the VITEK 2 susceptibility testing cards lacking an ESBL test was low (21–25%).

Conclusion: VITEK 2 susceptibility testing cards lacking an ESBL test are suitable for initial screening for ESBL production since they display high sensitivity. The E-test and the two tested disk diffusion methods reliably detect ESBL-producing isolates. In general, the E-test and the disk diffusion methods are used to confirm ESBL production in a specific isolate. More time is required to perform these extra confirmation tests following initial screening tests for ESBL production. However, the ESBL test containing VITEK 2 susceptibility testing cards make it possible to do both the screening and the confirmation in one test, allowing for faster and reliable ESBL detection.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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