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Investigative use only test card using the VITEK 2 system as compared to broth microdilution

Abstract number: P850

Buckner R., Fuller D., Davis T., Newcomer K., Mirrett S., Reller L., Smith-Moland E.

Objective: The purpose of this study was to demonstrate the effectiveness of antimicrobial susceptibility tests for Cefalexin (CN), Cefditoren (CDN), Cefsulodin (CFS), and Ceftobiprole (BPR) on the VITEK® 2 platform.

Methods: This multicentre trial tested Gram-negative isolates using an investigative use only (IUO) card (GN14) containing CN, CDN, CFS, and BRP. Challenge isolates (100), reproducibility isolates (best 10 strains), and quality control isolates (20 replicates of Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922) were tested at each site by automatic and manual dilution using the GN14 IUO card. Clinical isolates were tested by automatic dilution at all sites. Broth microdilution (BMD) reference testing was performed on all reproducibility, challenge, quality control and clinical isolates using the same standard inoculums prepared for the GN14 test cards. Reproducibility tests were performed in triplicate daily for three days. Essential agreement (EA) (within ± one log dilution) and categorical agreement (CA) (S/I/R) was determined for each microorganism/antimicrobial combination.

Results: Essential agreement for all 431 clinical isolates was > 93.0%, while categorical agreement was > 90.3% (Table 1). Reproducibility for the automatic diluted isolates was 100.0%, 98.9%, 97.8% and 98.9% for CN, CDN, CFS and BRP, respectively. For the manual dilution, reproducibility was 98.9%, 98.9%, 92.2% and 98.9% for CN, CDN, CFS and BRP, respectively. The EA, for 100 challenge experiments using automatic and manual dilution methods, was >96.0% for all antibiotics.

Table 1: Percent EA and CA for GN14 Card vs. BMD

Conclusions: This evaluation provides convincing evidence that the performance of antimicrobial susceptibility tests for CN, CDN, CFS and BRP on the VITEK® 2 platform is comparable to conventional testing in a clinical laboratory.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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