Which histological technique is used to identify fungi in tissue samples?

• A. Hematoxylin and eosin stain
• B. Giemsa stain
• C. Periodic acid–Schiff stain
• D. Immunohistochemistry

Answer: (B)

The identification of fungi in tissue samples is most effectively achieved using the Giemsa stain. This staining technique allows for the visualization of microorganisms, including fungi, due to its ability to stain the cytoplasm and nucleic acids of cells. Giemsa stain is particularly useful for observing the morphology of fungal elements, which often appear as distinct structures in tissue samples.

While other techniques have their own applications, they may not be as specific or effective in highlighting fungal elements. For instance, the hematoxylin and eosin stain is a routine stain used for general histological examination, providing information primarily about tissue structure and cellular details rather than specific pathogen identification. The periodic acid–Schiff stain is used to highlight polysaccharides, such as those found in fungal cell walls, but it is not the first choice for direct fungal identification in tissue. Immunohistochemistry, while powerful for detecting specific antigens, may not be routinely employed solely for fungi identification without specific antibodies.

Therefore, the Giemsa stain is the preferred method for identifying fungi in tissue samples, as it effectively demonstrates the unique characteristics and morphology of fungal organisms.