Gram Smears Image Acquisition and Integration Within WASPLab® Environment

Gram stain results are used by the clinician to enable initiation of antibiotic therapy prior to obtaining culture identifications. WASP™ and WASPLab® automation systems are supporting the entire clinical specimens testing workflow, from Gram smear preparation to automated imaging of bacterial culture plates. The Metafer™ slide scanning automated platform can generate gram images and QuickFISH™ Gram can allow easy reading.

The objective of this study was to evaluate a fully automated Gram testing, (using WASPLab® prepared Gram smears, Gram stained with traditional and QuickFISH™ reagents, Metafer™ system digital reading, WASPLab® interfacing) in order to facilitate Gram smears reading and results interpretation for the microbiology laboratories.

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In this study duplicate smears (n=360) were prepared from different specimens types collected in the appropriate LBM collection devices. Clinical specimens and blood cultures were loaded on the WASP™ for smear preparation and culture inoculation. One of each smear was Gram stained and read by the testing laboratory. The duplicate smears, 160 were stained with Gram QuickFISH™ (AdvanDx, Woburn, USA) and 200 were methanol fixed and Gram stained with an automated Wescor stainer. Both Gram and QuickFISH™ Gram stained smears were loaded on the automated Metafer™ slide scanning platform (MetaSystems, Germany). Smears were first scanned at 10x followed by 63x under oil. Images were acquired by the Metafer™ digital reading system. Both the MetaferTM and the WASPLab® software were interfaced and traditional Gram and QuickFISH™ Gram images were transferred to the corresponding sample in the WASPLab® resulting field showing the gram images next to the culture images. All Metafer™ generated gram images were reviewed by the microbiology laboratory staff on the WASPLab® monitor and results recorded.

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Good Gram results correlation was obtained between the manual microscopy results obtained at 100x under oil to the results of the Metafer™ generated images.. The image of the entire smear at 10x was used to assess smear quality and the cellularity differential using the feature of increasing the magnification up to 30x. The presence of Gram positive and gram negative bacteria was easily seen from the images acquired at 63x with the possibility of increasing the magnification up to 180x. Metafer™ is able to sort and quantify the microorganisms present on the QuickFISH™ stained smears into three classes: Gram positive (green), Gram negative (red) and fungi/yeasts (yellow).

Both the WASPLab® automation system and the Metafer™ slide scanning automated platform are facilitating Gram testing from smear preparation to reading and reporting of results, allowing reliable results both in term of quality and traceability. Metafer™ and Gram QuickFISH™ can provide a quantitative assessment of Gram results. The Gram images can also be accessed remotely for Microbiologist consultation and Gram stain images can also be used for Gram stain competency testing.