What is a Gram Stain Test?

Frequently Asked Questions:

What is the Gram Stain Test used for?

Gram stain test is mainly used to find out if you have some bacterial infection. From this test, you will know whether your bacterial infection is gram positive or gram negative and give preliminary information about the bacteria. Your doctor can confirm if bacteria is responsible for your symptoms and treat you accordingly from these details. Still confused, get a free second opinion

Understanding the test results of Gram Stain Test

When your Gram stain results are negative, which means that no traces of bacteria were found in your given samples. When the gram stain results are positive, that means bacteria were present in the sample. The result also specifies the details on the bacteria infected, the shape, size and quantity of bacteria present in the sample

Why do I need a Gram Stain Test?

You may need to do a gram stain test, if  you have the symptoms of bacterial infections or as directed by your physician. By this test you will be able to detect the presence of any bacteria or fungi in the sample taken from the site of the infection.

What happens during the Gram Stain Test?

The health care provider will collect the samples for the gram stains from the site of the suspected infection.

• Some samples may be collected using sterile swabs to obtain cells or exudate from the site of infection. Eg: wound sample, throat culture or from the thick mucus coughed up from the lungs.
• Other samples such as urine or sputum may be collected in a sterile container.
• Body fluids will be collected using a needle and syringe.

The sample will be then sent to the pathology lab for testing.

How do you perform a Gram stain test?

The Gram stain involves applying a sample collected from the infected area onto a glass slide and allowing it to dry. During the test the slide is treated with the specific stain and examined under a microscope by a trained technician . Any bacteria that may be present are categorised by colour and shape during the microscopic evaluation and will give you the results. The test is generally safe and no side effects are observed during the test.

What is Gram staining and why is it important?

Gram staining is a most used differential staining technique used in microbiological labs to test and differentiate the bacteria into gram positive bacteria and gram negative bacteria.  

By this test your physician confirms the diagnosis and helps him to get closer to find out what is causing your illness and determine which antibiotic will be most effective in treating your infection.

What test determines Gram positive or negative?

Gram stain colour test gives the clue as to what bacteria might be causing the infection in you. In this method the sample is treated with the gram stain and observed under the microscope. When bacteria coloured purple the result is, you are likely to have gram positive infection. When bacteria coloured pink or red, it means you are likely to have gram negative infection.

What Colour is Gram positive?

Gram positive bacteria appear purple or blue after gram staining.

Which antibiotics treat gram negative bacteria?

Gram negative bacteria are resistant to most available antibiotics. Some of the antibiotics which may treat gram negative bacteria are:

•   Ureidopenicillins (piperacillin)
•   Third- or fourth-generation cephalosporins (cefotaxime, ceftazidime)
•   Carbapenems (imipenem, meropenem)
•   Fluoroquinolones (ciprofloxacin)

Always take the advice of your consulting physician to choose the best treatment for you. 

What infections are caused by Gram positive bacteria?

The common gram positive infections are

• skin infections like cellulitis
• abscess
• bacterial pneumonia
• food poisoning
• surgical site infections
• urinary tract infections
• prostatitis, epididymitis
• sore throat, sinus infections
• pink eye
• pharyngitis
• pneumonia in newborn
• Anthrax
• listeriosis
• diphtheria
• respiratory infections

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