Parallel Comparison of Accuracy in Vitek2 Auto analyzer and API 20 E / API 20 NE Microsystems

Abstract: 302 samples were evaluated in the present study including 50 standard quality control samples, 62 repeatability samples and two separate batches of 90 and 100 samples of clinical isolates. Standard samples with registered ATCC or CCUG codes taken from international reference lab, used for performance test (quality control) of Vitek2 compact analyzer. The results of performance test showed total 98% accuracy. Detailed performance test results showed 100% accuracy for Gram positive & Gram negative bacteria and 95% accuracy for NH group members.Comparison between results of different culture media showed that use of conventional culture media instead of commercial branded culture media for preparing bacterial suspensions, doesn’t affect the result’s accuracy level in Vitek2 analyzer.Repeatability and reproducibility study of 62 samples including standard & clinical isolates results, showed 96.8% coalition in reproduced results by Vitek2 analyzer.The comparative results of 90 clinical samples via API 20E / API 20NE Microsystems and Vitek2 compact analyzer showed 77.8% “Complete coalition” or coalition in the "genus" and "species" levels of isolated micro organisms, 10.0% “partial coalition” which means coalition in the "genus" level but difference in "species” of isolates, 6.7% “no coalition” or different results in the "genus" and "species" levels of isolated micro organisms and 5.5% “unidentified” micro organisms by one of the applied methods. Comparative results also showed that total acceptable results rose from 80% in API system to 90% in vitek2 analyzer for clinical samples in this study.Survey on a random selection of 100 samples of Vitek2 reports showed an average analyze time of 5.5 hrs (330 Min.), where the minimum and maximum observed time were 2.75 hrs and 10.25 hrs respectively. Findings in this survey also showed 94% excellent, very good and acceptable identification of bacterial strain, 4% low discrimination, 2% non reactive bio-pattern and unidentified organism. The abundance of different bacteria in the random collection was composed of 71% gram negative, 24% gram positive and 5% NH group members. Escherichia coli (23.2% of total) were the popular bacteria in this collection.