SUITABILITY OF VITEK 2 SYSTEM IN IDENTIFICATION AND SUSCEPTIBILITY TESTING OF GRAM NEGATIVE BACTEREMIAS BY DIRECT...

Area of Science:

• Clinical Microbiology
• Diagnostic Accuracy Studies

Background:

• Accurate and rapid identification of Gram-negative bacilli in blood cultures is crucial for effective patient management.
• Conventional methods can have lengthy turnaround times, delaying appropriate antimicrobial therapy.

Purpose of the Study:

• To evaluate the accuracy of direct Vitek testing for identifying Gram-negative bacilli directly from positive blood cultures.
• To assess the accuracy of antimicrobial susceptibility testing (AST) performed directly from blood cultures using the Vitek system.

Main Methods:

• A validation study was conducted at Aga Khan University Hospital Nairobi.
• Twenty-two positive blood culture samples were analyzed using direct Vitek testing.
• Results were compared against conventional Vitek methods for identification and AST.

Main Results:

• Direct Vitek correctly identified 86% (19/22) of Gram-negative bacilli.
• Three samples (14%) were unidentified, with two showing pure growth on sub-culture.
• Minor discrepancies in AST were observed for some antibiotics, but these were deemed clinically insignificant.

Conclusions:

• Direct Vitek testing provides acceptable identification and AST results for Gram-negative bacilli from blood cultures.
• This method significantly reduces laboratory turnaround time by 12-24 hours compared to standard procedures.
• Direct Vitek testing is a viable option for improving efficiency in clinical microbiology laboratories.