Modified auramine-rhodamine stain contribution to identify mycobacterium tuberculosis

Ruivo, L.; Fialho, M. Pinto; Santos, H. S.; Tavares, J. A.; Ferreira, C.

http://hdl.handle.net/10400.21/21677

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Abstract(s)

Background & objectives: Mycobacterium tuberculosis (MT) infection often causes multiple organ granulomatous disease. Suspicious lesions are often biopsied to exclude malignancy. Ziehl-Neelsen (ZN) staining is the histological standard diagnostic tool for MT, although auramine-rhodamine (AR) appears to have better detection ratios. Methods: We evaluated all biopsies with suspected clinical tuberculosis (combined or not with microbiological testing), from January 2022 to September 2023 in a tertiary hospital center, with histological confirmation of granulomatous inflammation and tested with ZN staining. The biopsies were reevaluated using AR staining with a modified protocol in which phenol was replaced by a trident for cell membrane permeabilization. Results: The study comprised 53 cases, 27 females and 26 males. The most frequent biopsy sites were lymph nodes (38% - 20/53) and lung (36% - 19/53). Necrotizing granulomatous inflammation was found in 75% of cases (41/53), 32% of which (13/41) tested positive for ZN stain and were further confirmed with modified AR. From the remaining ZN-negative cases (68% - 28/41), 39% (11/28) tested positive in the microbiological study; from those, 73% (8/11) were positive using modified AR. Conclusion: Although ZN is the histological gold standard method to assess the presence of MT, its evaluation is hampered by the fact that the number of mycobacteria is often below the technique’s detection threshold. AR has greater sensitivity and easier fluorescence visualization, even at lower magnification and with fewer bacilli. Additionally, the proposed modification in the technical protocol for AR, makes it less harmful for the performer and does not compromise the quality of the technique.

Keywords

Mycobacterium tuberculosis Auramine-rhodamine Ziehl-Neelsen staining

URI

http://hdl.handle.net/10400.21/21677

Citation

Ruivo L, Fialho MP, Santos HS, Tavares JA, Ferreira C. Modified auramine-rhodamine stain contribution to identify mycobacterium tuberculosis. In: 36th European Congress of Pathology, Convention Centre Dublin (Ireland), September 7-11, 2024. Virchows Arch. 2024;485(Suppl 1):S164.