Gram Stain – Smear

The Gram Stain – Smear is a fundamental microbiological test used for the initial evaluation of bacterial infections. A thin smear of the patient’s sample is prepared on a glass slide and stained using a sequence of dyes (crystal violet, iodine, decolorizer, and safranin).

Based on the bacterial cell wall structure, organisms retain or lose the primary stain and appear purple (gram-positive) or pink/red (gram-negative) under a microscope. The test also helps assess bacterial shape (cocci, bacilli), arrangement, and the presence of pus cells, epithelial cells, or yeast. It provides quick preliminary information that guides early treatment decisions while awaiting culture results.