How is gram staining useful

Gram staining involves three processes: staining with a water-soluble dye called crystal violet, decolorization, and counterstaining, usually with safanin. Due to differences in the thickness of a peptidoglycan layer in the cell membrane between Gram positive and Gram negative bacteria, Gram positive bacteria with a thicker peptidoglycan layer retain crystal violet stain during the decolorization process, while Gram negative bacteria lose the crystal violet stain and are instead stained by the safranin in the final staining process.

The process involves three steps:. If bacteria were found, it will have certain qualities may provide important information about your infection:. Your results will also include information about the shape of the bacteria in your sample. Most bacteria are either round known as cocci or rod-shaped known as bacilli.

The shape can provide more information about the type of infection you have. Although your results may not identify the exact type of bacteria in your sample, they can help your provider get closer to finding out what's causing your illness and how best to treat it.

You may need more tests, such as a bacteria culture , to confirm what type of bacteria it is. Gram stain results may also show whether you have a fungal infection. The results may show what category of fungal infection you have: yeast or mold.

But you may need more tests to find out which specific fungal infection you have. Learn more about laboratory tests, reference ranges, and understanding results. If you are diagnosed with a bacterial infection, you will probably be prescribed antibiotics. It's important to take your medicine as prescribed, even if your symptoms are mild. This can prevent your infection from getting worse and causing serious complications. The information on this site should not be used as a substitute for professional medical care or advice.

Contact a health care provider if you have questions about your health. Gram Stain. What is a Gram stain? The two categories cause different types of infections: Gram-positive infections include methicillin-resistant Staphylococcus aureus MRSA , strep infections , and toxic shock. If your doctor suspects you have an infection, they may order a culture and gram stain to check for bacteria. If bacteria are present, this test can also help your doctor learn if the bacteria are gram negative or gram positive.

The difference between gram-negative and gram-positive bacteria can affect their recommended treatment plan. Your doctor may order a gram stain if you have symptoms of an infection. They may not know if the infection is bacterial, viral, fungal, or parasitic. These types of infections are typically treated differently. Different types of bacterial infections may also require different treatments. Your doctor can use a gram stain to learn if bacteria are responsible for your symptoms and what types of bacteria are present.

They may also order other tests to help diagnose your illness. In order to perform a gram stain, your doctor will need to collect a sample of body fluid or tissue for analysis. Their collection methods will vary depending on the type of sample they need. For example, to collect a sample of sputum, they may ask you to cough some into a specimen container. To collect a sample of urine, they may ask you urinate into a sample cup. To collect a sample of blood, they may perform a blood draw.

After they have collected the sample, they will send it to a laboratory for testing. Baron Medical Microbiology. London: Wright's Books; Bartholomew JW, Finkelstein H. Relationship of cell wall staining to gram differentiation. J Bacteriol ; Center for disease control and prevention CDC ; A new look at old tool, McClelland R. Gram's stain: The key to microbiology. Isenberg HD, editor. Clinical Microbiology Procedures Handbook. Washington, D.

C: American Society for Microbiology; Rand KH, Tillan M. Errors in interpretation of Gram stains from positive blood cultures. Am J Clin Pathol ; Barenfanger J, Drake CA. Interpretation of Gram Stains for the Non-microbiologist. Salton MR. The Bacterial Cell Wall. Amsterdam: Elsevier Press;