A New Slide-Staining System for Tuberculosis with Highly Flexible Programming

The aim of the study was to evaluate the capability of the instrument to achieve good sensitivity and to adjust the staining to individual circumstances and preferences throughout the world by providing a wide range of staining settings via an intuitive user interface.

According to the World Health Organization (WHO), microscopy of stained sputum samples is recognized as an accurate and economical approach for early detection of pulmonary Tuberculosis (TB) infections. Staining Mycobacterium tuberculosis and other acid-fast bacilli (AFB) require Carbol Fuchsin or Fluorescent staining techniques, both approaches coming with variations. Carbol Fuchsin staining usually utilizes Ziehl-Neelsen or Kinyoun primary stains with either Brilliant Green or Methylene Blue counterstains. Fluorescent staining techniques usually utilize Auramine O or Auramine Rhodamine primary stains and Potassium Permanganate or Thiazine Red as the counterstain. These staining methods are well recognized and it is generally accepted that Fluorescence microscopy provides a more rapid smear examination of stained smears and is more suitable for use in regional laboratories with large workloads. Given the increasing importance of fluorescence staining, the multicenter evaluation of the new system focused particularly on this approach.

ELITechGroup Biomedical Systems (Logan, UT, USA) has developed a new Aerospray TB Stainer/Cytocentrifuge (Model 7722). Like previous Aerospray TB models, this stainer automates the staining process of microscope slides without any risk of cross-contamination. The stainer utilizes significantly less stain than manual staining techniques and stains slides in only a quarter of the time usually required by manual staining. The optional Cytocentrifuge function of the instrument allows users to prepare samples evenly and uniformly on the microscope slide prior to staining, which is a significant advantage to increase the overall sensitivity of TB screening in patients with extra- pulmonary TB or with HIV co-infection.

The new Aerospray TB “series 2” utilizes a state-of-the-art touchscreen user interface and provides traceability for users, samples, and reagents. Above all, it is customizable to each laboratory’s needs, yet simple to operate. Various reagent combinations and stain routine adjustments are available in order to achieve the needs of AFB staining in the laboratory.

The stainer has been used in an international study carried out in Belgium, Namibia, South Africa, and USA, which included over 500 samples. These samples included direct and digested specimens (N-Acetylcystein – Phosphate buffer method), stained with different reagent combinations. Each sample was made in duplicate. At least one slide from each sample was stained by manual staining techniques and at least one slide was stained on the new Aerospray TB stainer. The slides were classified as AFB negative or AFB positive. The slide stained on the stainer was classified the same as the manually stained slide on >99.6% of the samples, thus demonstrating the high correlation between the automated and manual approaches.

Dennis Briscoe, General Manager of ELITechGroup Biomedical Systems said, “With the series 2 Aerospray TB (Model 7722), we’ve maintained the unique advantages of the Aerospray stainers and introduced a new slide-staining system for tuberculosis with highly flexible programming, good sensitivity and a user interface that is intuitive enough for routine clinical use.”

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