AAT Bioquest

What is gram stain used for?

Posted August 23, 2022


A Gram stain is a common laboratory test that is widely used to detect the presence of bacteria at the side of a suspected infection or in certain bodily fluids. If a bacterial infection is detected, the test further indicates if the infection is Gram-positive or Gram-negative. The test works by differentiating bacteria by the physical and chemical properties of their cell walls. Gram stain may also be used to diagnose fungal infections.

Additional resources

Gram Staining

MycoLight™ Rapid Fluorescence Bacterial Gram Stain Kit

Use of the gram stain in microbiology