Gram Stain Test

This test is performed to identify bacterial infections and find the underlying cause of different health conditions and symptoms, such as:

• Infected and sore skin
• Joint pain
• Signs of infections in the space surrounding the lungs
• Sexually transmitted diseases
• Intestinal infection 
• Fluid build-up in the layer surrounding the heart
• Signs of heart infections
• Prolonged cough
• Cough with peculiar odour and colour
• Unexplained swelling of joints

No special preparation is required before a gram stain test. Your doctor may recommend some arrangements for the test based on the sample to be collected.

The procedure of Gram stain test varies based on the tissue or fluid of the body to be tested. Different samples collected for gram stain test include:

• A stool, urine or sputum sample
• Body fluids collected using a needle from the space around lungs, the sac around the heart or joints
• A tissue sample, for example, from the skin or cervix

Risks of this test are based on the type of tissue that needs to be collected. Some tests may be absolutely pain-free, such as a urine test, whereas some tests, such as a biopsy may cause mild pain. Your doctor may provide pain-relieving medications to ensure comfort and to ease the sample collection process.

Presence or absence of bacterial infection indicates whether the reports are normal or abnormal.

Normal results: A negative gram stain test result is considered a normal result. It indicates the absence of bacterial infection, insufficient numbers of harmful bacteria or the presence of only “friendly” bacteria in the sample. Normally, bacteria live in certain parts of the body without causing any infection; for example, bacteria in the intestinal tissues are considered normal. However, the presence of bacteria in fluids, such as that of the spine, indicates a bacterial infection.

Normal gram stain test results state, ‘no organism seen’. 

Abnormal results: A positive gram stain test result indicates the presence of bacterial infection and is considered abnormal.

It will also state the details of the microorganisms, such as

• Gram-positive or gram-negative
• The shape of the bacteria, eg, round or rods
• Size and arrangement of bacteria
• Location of bacteria, fungi stained

In addition to the clinical symptoms, this information helps doctors to prescribe the most appropriate therapy for treatment.

In case of an abnormal result, your doctor may also recommend further tests such as a culture test to identify the specific microbe responsible for the infection.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational perspective and is in no way a substitute for medical advice from a qualified doctor.