Microscan Walk Away

The MicroScan WalkAway (Dade MicroScan Inc., West Sacramento CA, USA) is an automated ID and AST system that requires the ID and/or AST panels (96-well plates) be manually inoculated with bacteria isolated from clinical specimens and inserted into the WalkAway System. The panels are then incubated at 35°C for 16 to 42 h, depending on panel and organism type and results of readings. At the appropriate time, the WalkAway System automatically dispenses reagents into the appropriate biochemical wells and incubates the panels for an additional period of time (approximately 2-20 min, depending on the panel type). The WalkAway System then reads the panels. The identification of bacteria is based on measuring a series of biochemicals contained in panels designed for the speciation of most medically significant bacteria. The panels contain identification media consisting of substrates and/or growth inhibitors, which, depending on the species of the bacteria present, will exhibit color changes or increases in turbidity after incubation.

The panel may also contain series of antibiotics that are present in specified concentrations in the wells of applicable MicroScan panels. The WalkAway System reads the MICs and certain biochemicals and, if the criteria are met for adding reagents, reagents are added, and the panel is incubated for an additional period of time (approximately 5-30 min) depending on the panel type. The readings for the biochemicals needing no reagents and MIC wells (for combo panels) are stored prior to reagent addition. If additional incubation is necessary for the biochem-icals, the susceptibilities and certain biochemicals will be read first and stored.

The reagents will not be added until after additional incubation, at which time biochemicals not previously read will be determined. Following is the list of commonly used MicroScan panels: MicroScan Gram Pos ID panel, MicroScan Rapid Gram Pos ID panel, MicroScan Neg Type 2, MicroScan Rapid Neg ID Types 2 and 3, and MicroScan NHID (Dade MicroScan, 1998).

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