The Vitek-2 Compact system is a cutting-edge automated microbiology platform employed widely for bacterial identification and antimicrobial susceptibility testing (AST) in clinical and industrial laboratories. Its design notably enhances the speed, accuracy, and reproducibility of microbial diagnostics.
Principle of Vitek-2 Compact System
1.The system is based on advanced colorimetric technology that measures changes in light transmission through wells in reagent test cards.
2.Each well contains specific biochemical substrates reactive to bacterial enzymes.
3.As bacteria metabolize these substrates, enzymatic reactions alter the optical density, which is detected by the system’s optical sensors.
4.These changes in light transmittance serve as “fingerprints” for identifying a wide spectrum of microorganisms, covering about 98% of clinically relevant bacterial species.
5.The optical readings are compared against a large, continuously updated microbial database using sophisticated expert software.
6.This enables rapid, accurate identification alongside antimicrobial susceptibility profiles, helping clinicians select appropriate therapies faster.
7.The system’s miniaturized test cards reduce waste and operator error, while the compact automated design suits laboratories of all sizes.
Procedure for Culture Suspension Preparation
1.Begin with selecting several well-isolated colonies from a fresh agar plate of the microorganism to be tested.
2.Transfer these colonies aseptically into 3 ml of sterile saline (0.45%-0.5% NaCl, pH between 4.5 and 7.0).
3.Mix the suspension thoroughly using gentle vortexing or swirling to achieve homogeneity.
4.Adjust the turbidity of the bacterial suspension to match the 0.5 McFarland standard, which corresponds to approximately 1-2 x 10^8 colony-forming units per milliliter (CFU/ml).
5.Turbidity adjustment is typically done using a densitometer such as the Vitek 2 DensiCHEK Plus.
6.Proper standardization of inoculum density is critical to ensure accuracy and reproducibility in bacterial identification and AST.
7.Once standardized, the suspension is used to inoculate the Vitek-2 ID/AST test cards, which are then loaded into the system for automated processing.
8.The system incubates, monitors, and analyzes the biochemical reactions, providing reliable results within 6 to 8 hours.
