A Gram stain helps diagnose harmful bacteria. Under a Gram stain, different kinds of bacteria change one of two sets of colors (pink to red or purple to blue) under a special series of stains and are categorized as “gram-negative” or “gram-positive,” accordingly.
What can cause false results in Gram staining?
What can cause false results in Gram staining? Inappropriate specimen sampling, specimen processing, smear preparation, and prior antibiotic therapy are all factors that can have an adverse impact on Gram stain result. The inherent nature of some organisms may also produce misleading results; for example, Acinetobacter spp.
What are the steps in a Gram stain?
The Gram Stain
- Heat-fix a smear of a mixture of the bacterium as follows: a. ...
- Stain with Hucker's crystal violet for one minute (see Fig. 6). ...
- Stain with gram's iodine solution for one minute (see Fig. ...
- Decolorize by adding gram's decolorizer drop by drop until the purple stops flowing (see Fig. ...
- Stain with safranin for one minute (see Fig. ...
What are the results of Gram staining?
Why is gram staining important?
- An essential test for the rapid presumptive diagnosis of infectious agent
- Gram staining is utilized to distinguish the bacteria as a Gram positive or Gram negative
- Used To examine the morphology of bacteria
- Used To examine the arrangement of bacteria
- Used To find out the evidence of capsule
- Used To find out the evidence of spore
Is Gram stain positive or negative?
Gram-positive bacteria are bacteria with thick cell walls. In a Gram stain test, these organisms yield a positive result. The test, which involves a chemical dye, stains the bacterium’s cell wall purple. Gram-negative bacteria, on the other hand, don’t hold the dye. They stain pink instead.
Why is Gram staining important in diagnosis?
The main benefit of a gram stain is that it helps your doctor learn if you have a bacterial infection, and it determines what type of bacteria are causing it. This can help your doctor determine an effective treatment plan.
What is Gram staining and its importance?
Gram staining is a common technique used to differentiate two large groups of bacteria based on their different cell wall constituents. The Gram stain procedure distinguishes between Gram positive and Gram negative groups by coloring these cells red or violet.
How does Gram stain help in the identification of bacteria?
Gram staining differentiates bacteria by the chemical and physical properties of their cell walls. Gram-positive cells have a thick layer of peptidoglycan in the cell wall that retains the primary stain, crystal violet.
What does a Gram stain diagnose?
A Gram stain of a skin lesion is a laboratory test that uses special stains to detect and identify bacteria in a sample from the skin. The Gram stain method is one of the most commonly used techniques to quickly diagnose bacterial infections. A Gram stain is a test used to help identify bacteria.
What is the purpose of Gram staining quizlet?
What is the purpose of Gram Stain? To be able to determine the composition of the cell wall. The advantage of this staining procedure is that those cells that decolorize can be differetiated from the cells that resist decolorization by alcohol.
What is the advantage of the Gram stain over the simple stain?
What is the advantage of the Gram stain over a simple stain such as methylene blue? Gram staining highlights different bacteria types through the use of special dyes. It aids in the diagnosis of a specific organism and tells the difference between gram negative and gram positive bacteria.
What is the purpose of primary stain in Gram staining?
The Gram stain involves staining bacteria, fixing the color with a mordant, decolorizing the cells, and applying a counterstain. The primary stain (crystal violet) binds to peptidoglycan, coloring cells purple.
What is the importance of staining in microbiology?
The most basic reason that cells are stained is to enhance visualization of the cell or certain cellular components under a microscope. Cells may also be stained to highlight metabolic processes or to differentiate between live and dead cells in a sample.
How is Gram staining used in medicine?
A Gram stain is a test used to identify bacteria. It is one of the most common ways to quickly diagnose bacterial infection in the body.
Why is gram staining important?
In microbiology, gram staining is an important test used because it can determine the presence of bacteria in a sample, as well as differentiate between the two distinct bacteria species, which are gram-posi tive and gram-negative bacteria. This test also is especially important in medicine because the identification of the specific pathogen can ...
What is the process of identifying bacteria in a blood sample?
The process of identifying bacteria in the sample involves using different agents, such as crystal violet dye, iodine mordant, decolorant and safranin. After staining, bacteria differentiation is possible because gram-positive bacteria have a purple color ...
Why do bacteria have different colors?
After staining, bacteria differentiation is possible because gram-positive bacteria have a purple color while gram-negative bacteria have a pink color when viewed under a light microscope. A basic difference between these two types of bacteria is their cell walls.
Why do doctors use gram stain?
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.
Why do you need a gram stain?
The main benefit of a gram stain is that it helps your doctor learn if you have a bacterial infection, and it determines what type of bacteria are causing it. This can help your doctor determine an effective treatment plan.
What to do if your doctor suspects you have an infection?
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.
Why do Gram positive bacteria look purple?
Because of the staining technique used, gram-positive bacteria will appear purple under a microscope and gram-negative bacteria will appear pink. The shape, size, and quantity of bacteria present will also provide information about your infection.
How to do gram stain?
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 ...
Is it safe to get a gram stain on your urine?
There are no known risks involved in performing a gram stain on a sample of urine, stool, or mucus . If your doctor orders a gram stain on a sample of blood or tissue, some risks are involved in collecting the sample. For example, you may experience bruising, bleeding, or infection as a result of a blood draw.
Why do you need a Gram stain?
Why do I need a Gram stain? You may need this test if you have symptoms of a bacterial infection. Pain, fever, and fatigue are common symptoms of many bacterial infections. Other symptoms will depend on the type of infection you have and where in the body it is located.
What does a Gram stain show?
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.
What are the two main categories of bacterial infections?
These sites include the throat, lungs, and genitals, and in skin wounds. There are two main categories of bacterial infections: Gram-positive and Gram-negative. The categories are diagnosed based on the how the bacteria reacts to the Gram stain. A Gram stain is colored purple. When the stain combines with bacteria in a sample, ...
What is the color of a Gram stain?
A Gram stain is colored purple. When the stain combines with bacteria in a sample, the bacteria will either stay purple or turn pink or red. If the bacteria stays purple, they are Gram-positive. If the bacteria turns pink or red, they are Gram-negative. The two categories cause different types of infections:
What does it mean when there are no bacteria in a slide?
A laboratory professional will examine the slide under a microscope. If no bacteria were found, it means you probably don't have a bacterial infection or there weren't enough bacteria in the sample. If bacteria were found, it will have certain qualities may provide important information about your infection:
What is sputum culture?
Sputum culture. Sputum is a thick mucus that is coughed up from the lungs. It is different from spit or saliva. Your health care provider will ask you to cough up sputum into a special cup, or a special swab may be used to take a sample from your nose.
What is the shape of a bacteria?
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.
Why do you need a bacterial test?
Why the Test is Performed. You may have this test to diagnose an infection caused by bacteria. It can also identify the type of bacteria causing the infection. This test can help find the cause of various health problems, including: Intestinal infection or illness.
Where do bacteria live?
Some types of bacteria normally live in certain areas of the body, such as the intestines. Bacteria normally don't live in other areas, such as the brain or spinal fluid. Talk to your provider about the meaning of your specific test results.
What is STD in medical terms?
Sexually transmitted diseases (STDs) Unexplained swelling or joint pain. Signs of a heart infection or fluid buildup in the thin sac that surrounds the heart (pericardium) Signs of infection of the space around the lungs (pleural space)
How does a biopsy test feel?
How the Test will Feel. How the test will feel depends on the method used to take a sample. You may not feel anything, or you may feel pressure and mild pain, such as during a biopsy. You may be given some form of pain medicine so you have little or no pain.
What is direct gram staining?
Direct Gram staining and its various benefits in the diagnosis of bacterial infections. In the era of rapid development of molecular and other diagnostic methods, direct Gram staining (DGS) tends to remain in the background, although it can provide both microbiologists and clinicians numerous benefits. The aim of this review was to emphasize the ...
Why is DGS important?
Briefly, the DGS remains an easy, rapid, inexpensive and important method, which use should be encouraged in conditions of a standardized and controlled performance to avoid technical or interpretation errors.
Why is Gram stain important?
Because the bacteria are colored, not only is their Gram stain group identified, but their shape, size, and clumping pattern may be observed . This makes the Gram stain a valuable diagnostic tool for a medical clinic or lab.
What is Gram staining?
The Gram stain is a differential method of staining used to assign bacteria to one of two groups (gram-positive and gram-negative) based on the properties of their cell walls. It is also known as Gram staining or Gram's method.
What is the primary stain for Gram positive bacteria?
The primary stain ( crystal violet) binds to peptidoglycan, coloring cells purple. Both gram-positive and gram-negative cells have peptidoglycan in their cell walls, so initially, all bacteria stain violet. Gram's iodine ( iodine and potassium iodide) is applied as a mordant or fixative. Gram-positive cells form a crystal violet-iodine complex.
What is the primary stain for Gram staining?
The Gram stain involves staining bacteria, fixing the color with a mordant, decolorizing the cells, and applying a counterstain. The primary stain ( crystal violet) binds to peptidoglycan, coloring cells purple. Both gram-positive and gram-negative ...
How does Gram stain work?
How the Gram Stain Works 1 The primary stain ( crystal violet) binds to peptidoglycan, coloring cells purple. Both gram-positive and gram-negative cells have peptidoglycan in their cell walls, so initially, all bacteria stain violet. 2 Gram's iodine ( iodine and potassium iodide) is applied as a mordant or fixative. Gram-positive cells form a crystal violet-iodine complex. 3 Alcohol or acetone is used to decolorize the cells. Gram-negative bacteria have much less peptidoglycan in their cell walls, so this step essentially renders them colorless, while only some of the color is removed from gram-positive cells, which have more peptidoglycan (60-90% of the cell wall). The thick cell wall of gram-positive cells is dehydrated by the decolorizing step, causing them to shrink and trapping the stain-iodine complex inside. 4 After the decolorizing step, a counterstain is applied (usually safranin, but sometimes fuchsine) to color the bacteria pink. Both gram-positive and gram-negative bacteria pick up the pink stain, but it is not visible over the darker purple of the gram-positive bacteria. If the staining procedure is performed correctly, gram-positive bacteria will be purple, while gram-negative bacteria will be pink.
What is the process of dehydrating gram positive cells?
The thick cell wall of gram-positive cells is dehydrated by the decolorizing step, causing them to shrink and trapping the stain-iodine complex inside. After the decolorizing step, a counterstain is applied (usually safranin, but sometimes fuchsine) to color the bacteria pink.
What are some examples of Gram positive and Gram negative pathogens?
Not all bacteria identified by the Gram stain are associated with diseases, but a few important examples include: Gram-positive cocci (round): Staphylococcus aureus. Gram-negative cocci: Neisseria meningitidis. Gram-positive bacilli (rods): Bacillus anthracis.