Automated Microbial Diagnostics

Automated diagnostic analyzers, like the Vitek 2, rapidly identify pathogens and test antibiotic susceptibility.

Suspensions of pure microbial colonies are loaded into appropriate identification, or ID cards, and antibiotic susceptibility testing, or AST cards.

The ID cards contain multiple wells with various substrates that react with microbial enzymes.

Microbial metabolic activities cause changes in the color or turbidity over time, which are detected by the instrument.

The resulting biochemical profile is then matched with a database to identify the microbial species.

Simultaneously, the AST cards contain wells with increasing concentrations of different antibiotics to monitor bacterial growth by turbidity.

By observing growth, the system determines the susceptibility and the minimum inhibitory concentration of a particular antibiotic.

Results are compared to clinical standards, which classify bacteria as susceptible, intermediate, or resistant.

Finally, the system applies automated expert rules to validate results before reporting.