A comparative study of antibiotic gradient devices for the determination of tigecycline minimum inhibitory concentration

Abstract number: P771

Withey S.

Objectives: The ability to simply and accurately determine antimicrobial susceptibility is of fundamental importance to the clinical microbiology laboratory. The aim of this study was to compare the performance of the tigecycline Oxoid M.I.C.Evaluator (M.I.C.E.) (Thermo Fisher Scientific) with tigecycline Etest (bioMérieux) and the CLSI, BSAC and EUCAST agar and/or broth dilution methods.

Methods: Two hundred and thirteen clinically significant organisms were tested, including staphylococci, streptococci, haemophilus, anaerobes and Enterobacteriaceae. Overnight cultures were used to make a 0.5 McFarland suspension of each isolate (1.0 McFarland for anaerobic organisms) for both the agar and/or broth dilutions and plate inoculation. Inoculated plates and broths were incubated in appropriate conditions according to CLSI, BSAC and EUCAST methods. Results were used to determine the essential agreement (EA) of tigecycline M.I.C.E. strips and tigecycline Etest strips.

Results: Tigecycline M.I.C.E. strips achieved an EA greater than 90% across all groups of organisms for CLSI, BSAC and EUCAST methods. Etest equivalents scored less than 90% in five out of twenty cases for CLSI, three out of twenty cases for BSAC and four out of twenty cases for EUCAST. Tigecycline M.I.C.E. strips had an EA equivalent to or better than Etest in all groups and sub groups of organisms tested when following the CLSI, BSAC and EUCAST methods.

Conclusion: Tigecycline M.I.C.E. strips are an effective and reliable alternative to traditional agar/broth dilution methods for determination of tigecycline MIC. Tigecycline M.I.C.E. strips performed consistently better than tigecycline Etest strips and statistically significantly better than tigecycline Etest when following the CLSI (P = 0.032) and BSAC (P = 0.014) methods.

Session Details

Date: 07/05/2011
Time: 00:00-00:00
Session name: Abstracts of 21st ECCMID / 27th ICC
Location: Milan, Italy, 7 - 10 May 2011
Presentation type:
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