Mikrobivärjäykset

Mikrobivärjäykset are laboratory techniques used to enhance the visibility of microorganisms under a microscope. They involve the application of dyes or stains that selectively bind to structural components of bacterial, fungal, or protozoan cells, allowing for differentiation, identification, and characterization of microorganisms in clinical, environmental, or research settings.

The main purpose of microbial staining is to improve contrast in light microscopy, reveal cell morphology, and differentiate between Gram‑positive and Gram‑negative bacteria, among other distinctions. Classic staining methods include the Gram stain, which uses crystal violet, iodine, alcohol dehybridization, and safranin. The Gram technique distinguishes bacteria based on cell‑wall thickness and composition. Following the Gram stain, additional methods such as the acid‑fast stain, which employs carbol fuchsin and acid alcohol, identify mycobacteria by their high lipid content. The capsule stain, using mucicarmine, nigrosin, or India ink, highlights extracellular polysaccharide capsules around bacterial cells.

Other specialized stains include the indospot or nitrate reduction tests for metabolic typing, and the acid alcohol‑resistant differential stains used in distinguishing yeast colonies on agar. Fluorescence microscopy can be employed with fluorescent dyes or antibodies to detect specific proteins or antigens, providing higher sensitivity and specificity.

In clinical microbiology, timely and accurate staining informs diagnosis, guides antimicrobial therapy, and contributes to epidemiological surveillance. These techniques remain foundational despite advances in molecular diagnostics, because they provide rapid, cost‑effective, and visual confirmation of microbial presence and characteristics.