A bacteria culture is a test to confirm whether you have a bacterial infection. The test can also identify what type of bacteria caused the infection, which helps guide treatment decisions. For a bacteria culture test, a healthcare provider takes a sample of blood, stool, urine, skin, mucus or spinal fluid.
Bacteria are simple, single-cell organisms that were among the first forms of life on Earth. They live all around us and inside us. Most bacteria are harmless or even beneficial, but some can cause diseases and associated symptoms. In fact, bacteria cause most infectious diseases.
A bacteria culture is a test to confirm whether you have a bacterial infection. The test can also identify what type of bacteria caused the infection. It can also help healthcare providers choose the most effective treatment because certain antibiotics are more effective against specific bacteria.
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A bacteria culture test is a common tool. A healthcare provider uses the test when a person has symptoms of a bacterial infection, such as:
Various healthcare providers may order the test and collect the sample to send to a lab, including:
For a bacteria culture test, a healthcare provider takes a small sample of a substance from your body. The sample area depends on what symptoms you have and what infection your healthcare provider suspects.
The provider sends the sample to a laboratory. At the lab, experts use special techniques to deliberately encourage any micro-organisms in the sample to grow and multiply. Then they examine the sample under a microscope to identify bacteria or yeast.
Bacteria can be sampled from various areas of your body or substances inside your body, depending on the type of infection suspected. The different types are:
Most bacteria culture tests don’t require any preparation. But ask your healthcare provider whether there are any special instructions.
Bacteria culture tests have a very low risk of any complications. Most have no known risks. Blood and CSF cultures involve a small chance of infection or bleeding because those tests involve a needle puncture in the skin. A CSF culture is usually done on someone who is critically ill or likely to become critically ill in the near future.
After the sample goes to the lab, lab staff use specific techniques to make the cells multiply and grow. This gives experts enough bacterial cells to examine under a microscope or test for specific chemical reactions, including susceptibility to various antibiotics. The process takes one to five days, depending on the type of bacteria.
If the sample contains enough bacteria, the lab confirms an infection. The lab will tell the healthcare provider what type(s) of bacteria were found.
The lab also might run antimicrobial susceptibility testing (AST). AST is a lab test that identifies which treatment regimen would be most effective against the type of infection you have. After getting these results your provider may determine that a different antibiotic would work better than one initially prescribed because certain antibiotics are more effective against specific bacteria.
A note from Cleveland Clinic
A bacteria culture is a test to identify whether you have a bacterial infection. It can be performed on a sample of blood, stool, urine, skin, mucus or spinal fluid. Using this type of test, a healthcare provider can identify what caused an infection and determine the most effective treatment.
Last reviewed by a Cleveland Clinic medical professional on 11/24/2021.
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