Joint fluid culture
What is a joint fluid culture?
A joint fluid culture is a laboratory test used to detect the presence of bacteria in the fluid that lubricates a joint, known as joint fluid. The joint fluid culture is typically used to diagnose a joint infection, such as septic arthritis. Joint fluid cultures may also help determine the cause of a persistent joint inflammation.
Preparation for a joint fluid culture
No preparation is required for a joint fluid culture. A doctor must collect the joint fluid sample. This is typically done with a needle and a syringe.
Procedure for a joint fluid culture
A doctor will use a needle and syringe to withdraw a small amount of fluid (usually 1 to 2 milliliters) from the affected joint. The fluid sample is then taken to a laboratory for analysis. Lab technicians will look at the sample under a microscope to identify any bacteria present and then place it in microbiological media to identify any bacteria that can be grown. Blood cultures may be performed in addition to joint fluid cultures to help identify the bacteria causing an infection.
Types of joint fluid culture
Joint fluid cultures may focus on general bacterial cultures or they may be more specific. Among the specific cultures that may be performed on joint fluid includes:
- Staphylococcus aureus culture
- Pseudomonas aeruginosa culture
- Streptococcus species culture
- Mycobacterium species culture
- Gram stain
Risks associated with a joint fluid culture
A joint fluid culture is considered a low risk procedure. The only risk associated with the procedure is that of a small amount of bleeding from the needle puncture site. The risk of infection is minimized if the doctor performing the procedure takes safety and sanitary precautions.
Why a joint fluid culture is performed
The main reason why a joint fluid culture is performed is to detect a bacterial infection in an affected joint. Joint fluid cultures are also used to monitor the effectiveness of treatment for joint infections.
When a joint fluid culture may be performed
A joint fluid culture is typically ordered when a doctor suspects that a joint infection is present. Joint fluid cultures may also be performed to monitor the effectiveness of treatment for joint infections.