DOI: 10.4103/ijamr.ijamr_4_26 ISSN: 2349-4220

Comparative Evaluation of Colistin Minimum Inhibitory Concentration Determination by Broth Microdilution and VITEK2 in Clinical Acinetobacter Isolates

Shipha Hashmi, Vinita Khare, Sarvodaya Tripathy
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Abstract

Background:

Acinetobacter baumannii is an emerging multidrug-resistant pathogen that is a common cause of nosocomial infections. Colistin is a last resort drug for the treatment. The broth microdilution (BMD) method of antimicrobial susceptibility testing is regarded as the gold standard. Automated systems, such as VITEK2, produce rapid results, but their performance requires further investigation.

Aims and Objective:

This study aimed to compare the MIC obtained from an automated system like VITEK2 to the gold standard MIC by BMD, for the Acinetobacter isolates obtained from different clinical samples.

Materials and Methods:

A cross-sectional study was conducted over 6 months on a total of 62 pure clinical isolates of Acinetobacter spp. obtained from various clinical samples. BMD (CLSI 2025 recommendations) and VITEK2 tests were used to determine the minimum inhibitory concentration of colistin. Comparative performance was measured using essential agreement (EA), categorical agreement (CA), major errors (MEs), and very ME (VMEs).

Results:

The agreement study found that the EA was 91.9% and the CA was 95.1%. The ME rate was 3.3%, and the VME rate was 33.3%.

Conclusion:

Accurate and practical colistin susceptibility testing procedures should be implemented. Testing larger sample sizes and exploring molecular mechanisms are essential.

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