Does this test have other names?
Methicillin-resistant Staphylococcus aureus culture
What is this test?
This test looks for bacteria called methicillin-resistant Staphylococcus aureus (MRSA) in a fluid sample from your body.
MRSA is a type of staph bacteria that is resistant to certain antibiotics. These include methicillin and related medicines like oxacillin, penicillin, and amoxicillin. MRSA infections can be life-threatening. Outbreaks can affect patients and visitors in hospitals and other healthcare settings. They can also occur in the community.
For the test, your fluid sample will be put in a dish with special nutrients to help any bacteria grow. It can take up to 48 hours to get the results.
Rapid testing is available with the BD GeneOhm StaphSR test. This can detect MRSA within 5 hours of culturing a sample. Other tests are being developed.
Why do I need this test?
You may have this test if you have symptoms of a staph infection. Symptoms depend on the type and stage of the infection. Most MRSA infections affect the skin. A skin infection is usually red, painful, swollen, and oozing pus.
You may also have this test if you are being treated for a MRSA infection to see whether the treatment is working.
What other tests might I have along with this test?
Your healthcare provider may also order a nucleic acid amplification test, such as the polymerase chain reaction (PCR). PCR is used to find the mecA gene. This gene can make staph bacteria resistant to certain antibiotics.
Other tests are often ordered when cultures are done to find out how far the infection has spread. They may also be ordered to look for other causes of symptoms. These tests include:
Complete blood count with differential
Chemistry panel, including kidney and liver function
Echocardiogram, if your provider thinks you have a bloodstream infection
MRI, if your provider thinks you have a bone infection
Discuss the results of these other tests with your healthcare provider.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your healthcare provider.
Normal results are negative, meaning that no bacteria were found in your culture. A positive culture means you may have a MRSA infection.
How is this test done?
This test requires a fluid sample. The sample is often taken from the infection site, such as a wound, using a sterile swab. Fluid samples can also be taken from saliva, urine, or blood. A sample may be taken from your nose to find out whether you are "colonized" with MRSA. That means you have MRSA living on your skin but aren't necessarily infected with MRSA.
For the urine test, your healthcare provider or lab technician will give you a sterile container to collect the sample. For the blood test, a blood sample is drawn through a needle from a vein in your arm.
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
Other factors aren't likely to affect your results.
How do I get ready for this test?
You don't need to prepare for this test.
- Freeborn, Donna, PhD, CNM, FNP
- Snyder, Mandy, APRN