Related Experiment Video
Updated: Sep 6, 2025
Author Spotlight: Accelerating Diagnostic Accuracy with Direct Identification of Gram-Negatives from Blood Culture Bottles
Published on: May 24, 2024
Performance Evaluation of the VITEK2 and Sensititre Systems to Determine Colistin Resistance and MIC for
Hae-Sun Chung1,2, Soo-Kyung Kim1, Chorong Hahm1,3
1Department of Laboratory Medicine, Ewha Womans University College of Medicine, Seoul 07985, Korea.
Abstract:
Performances of the colistin antimicrobial susceptibility testing (AST) systems of Acinetobacter baumannii vary depending on the manufacturer, and data on colistin-resistant A. baumannii are limited. We evaluated the VITEK2 and Sensititre systems to determine colistin resistance and minimum inhibitory concentration (MIC) for A. baumannii isolated from a clinical microbiology laboratory. A total of 213 clinical A. baumannii isolates were tested, including 81 colistin-resistant A. baumannii. ASTs were performed using the VITEK2 and Sensititre systems according to the manufacturer's instructions. Reference MICs for colistin were determined using the manual broth microdilution method (BMD). The results of the two AST methods were compared with the BMD results. VITEK2 and Sensititre systems showed category agreements of 95.3% and 99.1%, respectively. VITEK2 had a relatively high very major error (VME) rate (9.9%). Sensititre reported higher MICs than the reference method for the susceptible isolates and showed low essential agreement. In conclusion, the automated systems investigated in this study showed good category agreements for colistin AST of A. baumannii. However, VITEK2 had a high VME rate, and Sensititre had differences in MIC results. Colistin AST remains a challenging task in the clinical laboratory.
Insights
Evaluating colistin antimicrobial susceptibility testing (AST) systems for Acinetobacter baumannii reveals performance variations. While both VITEK2 and Sensititre showed good category agreement, VITEK2 had a high very major error rate, and Sensititre reported differing MIC results.
Area of Science:
- Clinical microbiology
- Antimicrobial resistance
- Infectious diseases
Background:
- Colistin antimicrobial susceptibility testing (AST) systems for Acinetobacter baumannii exhibit manufacturer-dependent performance variability.
- Limited data exist on colistin-resistant A. baumannii, necessitating accurate susceptibility testing methods.
Purpose of the Study:
- To evaluate the performance of VITEK2 and Sensititre systems for determining colistin resistance and minimum inhibitory concentration (MIC) in A. baumannii.
- To compare the accuracy of these automated systems against the reference broth microdilution (BMD) method.
Main Methods:
- Tested 213 clinical A. baumannii isolates (81 colistin-resistant) using VITEK2 and Sensititre systems.
- Determined reference colistin MICs via manual broth microdilution (BMD).
- Compared AST results from VITEK2 and Sensititre against BMD reference values.
Main Results:
- VITEK2 and Sensititre systems achieved category agreements of 95.3% and 99.1%, respectively, when compared to BMD.
- VITEK2 exhibited a high very major error (VME) rate of 9.9%.
- Sensititre reported higher MICs for susceptible isolates and showed low essential agreement with the reference method.
Conclusions:
- Automated systems demonstrate good category agreement for colistin AST in A. baumannii.
- VITEK2's high VME rate and Sensititre's MIC discrepancies highlight challenges in colistin susceptibility testing.
- Accurate colistin AST for A. baumannii remains a complex issue for clinical laboratories.
More Related Videos
12:03Antimicrobial Synergy Testing by the Inkjet Printer-assisted Automated Checkerboard Array and the Manual Time-kill Method
Published on: April 18, 2019
09:59Application of the Intelligent High-Throughput Antimicrobial Sensitivity Testing/Phage Screening System and Lar Index of Antimicrobial Resistance
Published on: July 21, 2023
