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Disc diffusion-based screening tests for extended-spectrum β-lactamases in Haemophilus influenzae

Citation

Tristram, SG and Bozdogan, B and Appelbaum, PC, Disc diffusion-based screening tests for extended-spectrum β-lactamases in Haemophilus influenzae, Journal of Antimicrobial Chemotherapy, 55, (4) pp. 570-573. ISSN 0305-7453 (2005) [Refereed Article]

DOI: doi:10.1093/jac/dki036

Abstract

Objectives: To establish a suitable screening test for the detection of extended-spectrum β-lactamases (ESBLs) in Haemophilus influenzae. Methods: Double disc diffusion tests using cephalosporin discs adjacent to an amoxicillin/clavulanate 3 μg disc, prediffusion tests, where an amoxicillin/clavulanate 3 μg disc was prediffused before being replaced with a cephalosporin disc, and combination cephalosporin/clavulanate discs were used to screen recombinant H. influenzae expressing cloned ESBLs. Methods initially determined to be suitable were validated by testing a range of clinical strains. Results: Enhanced zones around cephalosporin discs due to synergy with an adjacent amoxicillin/clavulanate disc were not reliably demonstrated with the recombinant H. influenzae strains expressing ESBLs. Cefotaxime 5 μg or 30 μg and cefpodoxime 10 μg discs prediffused with an amoxicillin/clavulanate 3 μg disc, and cefotaxime 30 μg/clavulanate 10 μg and cefpodoxime 10 μg/clavulanate 1 μg combination discs all gave zone sizes ≥5 mm greater than the corresponding plain disc for all recombinant ESBL-producing strains. None of the clinical strains gave enhanced zones. Conclusions: Cefotaxime 5 or 30 μg or cefpodoxime 10 μg discs prediffused with an amoxicillin/clavulanate 3 μg disc, or cefotaxime 30 μg/clavulanate 10 μg and cefpodoxime 10 μg/clavulanate 1 μg combination discs are all suitable for screening H. influenzae isolates for the presence of ESBLs. ESBL-producing strains should show an increase in zone diameter of ≥5mm compared with the corresponding plain cephalosporin disc. © The Author 2005. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Medical and Health Sciences
Research Group:Medical Microbiology
Research Field:Medical Bacteriology
Objective Division:Health
Objective Group:Clinical Health (Organs, Diseases and Abnormal Conditions)
Objective Field:Infectious Diseases
Author:Tristram, SG (Dr Stephen Tristram)
ID Code:32728
Year Published:2005
Web of Science® Times Cited:4
Deposited By:Health Sciences A
Deposited On:2005-08-01
Last Modified:2006-04-01
Downloads:0

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