Suitability of Vitek 2 System in Identification and Susceptibility Testing of Gram Negative Bacteremias by Direct Inoculation

Document Type



Pathology (East Africa)


Objective: To verify the accuracy of direct Vitek testing for blood cultures with Gram-negative bacilli.

Design: Validation study.

Setting: Aga Khan University Hospital Nairobi.

Subjects: Twenty two positive blood cultures.

Main outcome measures: Correct bacteria identification and errors for susceptibility testing.

Results: Of the 22 samples analysed 19(86%) were correctly identified by direct Vitek testing and three (14%) were unidentified. Of the three, one had mixed growth and the other two had pure growth on sub-cultures. Of the 19 cultures with antimicrobial susceptibility testing by direct Vitek, three had discrepancies for some antibiotics when compared with the conventional Vitek method. These discrepancies were minor errors that would not have had any clinical impact.

Conclusion: These data suggest that direct Vitek would provide acceptable identification and antimicrobial susceptibility testing results for Gram-negative bacilli. Compared to the standard method, the direct Vitek method would reduce turnaround time by at least twelve to twenty four hours.

Publication (Name of Journal)

East African Medical Journal