Automated Microbial Diagnostics

The Vitek 2 loads a pure microbial suspension into ID cards containing wells with various biochemical substrates. As the microorganism metabolizes these substrates, color or turbidity changes occur and are detected by the instrument. The resulting biochemical profile is matched against an extensive database to identify the microbial species accurately and support rapid identification of pathogens.

ID cards are specialized testing cards containing multiple wells with predefined biochemical substrates. Different cards target Gram-negative bacteria, Gram-positive bacteria, or yeasts. The microorganism metabolizes substrates in each well, producing measurable changes in color or turbidity that the analyzer monitors to generate a unique biochemical activity profile.

AST cards contain wells with increasing concentrations of different antibiotics. The analyzer tracks microbial growth over time in each well. Absence or reduction of growth indicates susceptibility, while visible growth reflects resistance. The system calculates the minimum inhibitory concentration, the lowest antibiotic concentration preventing visible growth.

The minimum inhibitory concentration (MIC) is the lowest concentration of an antibiotic that prevents visible microbial growth. MIC values are interpreted using clinical guidelines like CLSI or EUCAST to classify bacteria as susceptible, intermediate, or resistant. This classification guides clinicians in selecting appropriate antimicrobial therapy.

Automated systems like Vitek 2 shorten diagnostic timelines compared to manual methods, enabling clinicians to initiate targeted antimicrobial therapy earlier. Rapid results improve patient outcomes, support antimicrobial stewardship by limiting inappropriate antibiotic use, and help control the spread of resistant organisms in clinical settings.

After the Vitek 2 generates identification and susceptibility results, automated expert rules validate the findings before reporting. These rules apply quality control checks and clinical logic to ensure accuracy and reliability. This validation step reinforces the clinical value of the technology and prevents erroneous results from reaching clinicians.

Pure microbial colonies ensure accurate identification and susceptibility testing by eliminating contamination from mixed organisms. A standardized suspension from isolated colonies is inoculated into ID and AST cards, allowing the analyzer to generate reliable biochemical profiles and growth responses specific to a single pathogen.