Joint fluid Gram stain is a laboratory test to identify bacteria in a sample of joint fluid using a special series of stains (colors). The Gram stain method is one of the most commonly used methods to rapidly diagnose bacterial infections.
Alternative NamesGram stain of joint fluid
How the test is performedA sample of joint fluid is needed. For information on how this procedure is done, see joint fluid aspiration.
The fluid sample is sent to a lab where a small drop is placed in a very thin layer onto a microscope slide. This is called a smear. Several different colored stains are applied to the sample. The laboratory personnel will look at the stained smear under a microscope to see if bacteria are present. The color, size, and shape of the cells help identify the bacteria.
How to prepare for the testFor information on how to prepare for the removal of joint fluid, see joint fluid aspiration.
How the test will feelFor information on how it will feel when the joint fluid is removed, see joint fluid aspiration.
Why the test is performedThe test is performed when there is unexplained swelling, joint pain, and inflammation of a joint, or to check for suspected joint infection.
Normal ValuesA normal result means no bacteria are present on the gram stain.
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results meanAbnormal results mean bacteria were seen on the Gram stain. This may be a sign of a joint infection, for example, gonococcal arthritis or Arthritis due to Staphylococcus aureus.
What the risks areThere is no risk to the patient associated with a Gram stain. For information regarding risks related to the removal of joint fluid, see joint fluid aspiration.
ReferencesEspinoza LR. Infections of bursae, joints, and bones. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 293.
Ohl CA. Infectious arthritis of native joints. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Churchill Livingstone Elsevier; 2009:chap 102.
Joint fluid Gram stain is a laboratory test to identify bacteria in a sample of joint fluid using a special series of stains (colors). The Gram stain method is one of the most commonly used methods to rapidly diagnose bacterial infections.
Alternative NamesGram stain of joint fluid
How the test is performedA sample of joint fluid is needed. For information on how this procedure is done, see joint fluid aspiration.
The fluid sample is sent to a lab where a small drop is placed in a very thin layer onto a microscope slide. This is called a smear. Several different colored stains are applied to the sample. The laboratory personnel will look at the stained smear under a microscope to see if bacteria are present. The color, size, and shape of the cells help identify the bacteria.
How to prepare for the testFor information on how to prepare for the removal of joint fluid, see joint fluid aspiration.
How the test will feelFor information on how it will feel when the joint fluid is removed, see joint fluid aspiration.
Why the test is performedThe test is performed when there is unexplained swelling, joint pain, and inflammation of a joint, or to check for suspected joint infection.
Normal ValuesA normal result means no bacteria are present on the Gram stain.
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results meanAbnormal results mean bacteria were seen on the Gram stain. This may be a sign of a joint infection, for example, gonococcal arthritis or arthritis due to Staphylococcus aureus.
What the risks areThere is no risk to the patient associated with a Gram stain. For information regarding risks related to the removal of joint fluid, see joint fluid aspiration.
ReferencesMatteson EL, Osmon DR. Infections of bursae, joints, and bones. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 280.
Ohl CA. Infectious arthritis of native joints. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Churchill Livingstone Elsevier; 2009:chap 102.
Reviewed ByReview Date: 11/13/2011
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The Gram stain is performed on a sediment of the CSF and is positive in at least 60% of cases of bacterial meningitis.
A gram-negative diplococcus
A gram stain is a cow
Protists are often stained using a silver stain, not a Gram stain.
gram -
The Gram stain is performed on a sediment of the CSF and is positive in at least 60% of cases of bacterial meningitis.
A gram-negative diplococcus
A gram stain is a cow
The gram stain uses a decolorizing product so it is possible to differentiate between the gram and the gram cells. Gram positive cells stain purple in color.
Gram stain
Gram Negative
Protists are often stained using a silver stain, not a Gram stain.
The Gram stain is used for bacteria and not for viruses.
Bacteria stain either gram-positive or gram-negative based on the presence or absence of a cell wall. Viruses do not pick up a gram stain.
Hans Christian Gram invented this stain in 1884
gram -
Bacteria stain either gram-positive or gram-negative based on the presence or absence of a cell wall. Viruses do not pick up a gram stain.