Blood Culture Test

What is Blood Culture Test? 

Blood culture checks for foreign microorganisms like bacteria, yeast, and other microorganisms in the blood. Having these pathogens in the bloodstream may be a sign of an infection. This condition is known as bacteremia. A positive blood culture means that the bacteria are present in the blood.

This type of infection involves the blood, which circulates throughout the entire body. Bacteria that start on the skin or in the lungs, urine, or gastrointestinal tract are common sources of blood infections.

What are the other names for the Blood Culture Test? 

The other names are: Blood culture and sensitivity, Blood C/S, and Blood culture aerobic test. 

What are the test parameters included in the Blood Culture Test?

There is only one parameter.

What does a Blood Culture Test measure?

A blood culture test is a procedure done to diagnose infection in the blood and identify the cause. These infections of the bloodstream are most commonly caused by bacteria or bacteremia, but may also be caused by yeasts or other fungi (fungemia) or by a virus (viremia). Although the blood can be used to test for viruses, this test focuses on the use of blood cultures to diagnose and identify bacteria and fungi in the blood.

The infection typically originates from some of the other specific sites within the body, spreading from that site when a person has a severe infection and the immune system cannot confine it to its source. For example, a urinary tract infection may spread from the bladder and/or kidneys into the blood, and then it can be carried throughout the body, infecting other organs and causing serious trouble. Septicemia refers to an infection of the blood, while sepsis is the body’s serious, overwhelming, and sometimes a life-threatening response to infection. This condition often requires prompt and aggressive treatment, usually in the intensive care unit of a hospital.

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On the other hand, serious complications can result from an infection of the blood. Endocarditis is an inflammation and infection of the lining of the heart and/or of the heart valves that can result from a bloodstream infection. People who have prosthetic heart valves or prosthetic joints have a higher risk of a systemic infection following the surgery, although these infections are not common.

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People with a weak immune system due to an underlying disease, such as leukaemia or HIV/AIDS, or due to immunosuppressive drugs such as those given for chemotherapy, have a higher risk of blood infections as their immune systems are less capable of killing the microbes which occasionally enter the bloodstream. These bacteria and yeast may also be introduced directly into the bloodstream through intravenous drug use or through intravenous catheters or surgical drains.

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For blood cultures, multiple blood samples are usually collected for testing and from different veins to increase the likelihood of detecting the bacteria or fungi that may be present in small numbers and/or can enter the blood intermittently. This is also done to help ensure that any bacteria or fungi detected are the ones causing the infection and not contaminants.

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These blood cultures are incubated for several days before being reported as negative. Some of the types of bacteria and fungi grow more slowly than others and may take a longer time to detect if initially present in low numbers.

When the blood culture is positive, the specific microbe causing the infection is identified, and an antibiotic sensitivity test is performed. It informs the healthcare practitioner which antibiotics are most likely to be effective for the treatment.

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In many laboratories, the blood culture testing process is automated with analysers continuously monitoring techniques for the growth of bacteria or fungi. This allows for the timely reporting of the results and for the healthcare practitioner to direct antimicrobial therapy for the specific microbe present in the blood. This is because treatment must be given as soon as possible in cases of infection. A broad-spectrum antimicrobial that is effective against several types of bacteria is usually given intravenously while waiting for blood culture results. Antimicrobial therapy can be changed to a more targeted antibiotic therapy once the microbe causing the infection is identified. 

What’s the normal range of Blood Culture Test? 

Blood culture yields no growth after 48 to 168 hours of incubation.

Who should get a Blood Culture Test? 

Blood culture testing is generally recommended if the doctor believes that you may have an infection in the blood. The doctor can suspect that you have an infection in your blood if you have any symptoms of infection. Infection is an inflammatory reaction that can occur if dangerous bacteria or other germs are in the bloodstream. Sepsis can become severe and life-threatening. The symptoms of sepsis that can lead the doctor to suggest a blood culture test include

1. Fever
2. Chills
3. Fast heartbeat
4. Rapid breathing
5. Low blood pressure
6. Confusion
7. Gastrointestinal problems

A blood culture test might also be recommended if you have an infection that is often caused by germs in the blood.

Examples of these infections include:

1. Infections of the heart valves
2. Infections affecting the bones
3. Meningitis is an infection in the tissue surrounding the brain and spinal cord.
4. Infections occur around implantable medical devices like catheters, artificial joints, or pacemakers.

This blood culture testing can also be recommended if you have an infection and are at a higher risk of developing more serious complications. In addition, with some types of infectious conditions, such as severe pneumonia, blood culture tests may be done alongside culture tests that use other body fluids or tissue.

Are there any preparations needed for the Blood Culture Test?

Fasting is not required for this test. Please ask the doctor if there are any precautions to be taken.

What is the cost of a Blood Culture Test?

What is the type of sample required? 

This test requires a blood sample.

Who processes a Blood Culture Test?

A healthcare provider, who is also called a phlebotomist, usually performs blood draws, including those for blood culture tests, but any healthcare provider trained in drawing blood can perform this task. These samples are sent to a lab where a medical laboratory scientist prepares the samples and performs the tests on analysers or manually. 

What should I expect during my Blood Culture Test?

You may expect the experience the following during the blood test or a blood draw:

1. You can feel the experience the following during the blood test or a blood draw
2. You have to sit comfortably on the chair, and a phlebotomist will check your arms for an easily accessible vein. This is the inner part of the arm on the other side of your elbow.
3. Once the phlebotomist has located a vein, they will disinfect the area with an alcohol swab and iodine solution.
4. They will insert a needle into your vein to draw a blood sample. They might feel like a small pinch.
5. After they pricked the needle, the required amount of blood will be drawn in a test tube.
6. When they have drawn enough blood for the test, they’ll remove the needle and hold a cotton ball or gauze on the site to stop any bleeding.
7. They will apply a band-aid over the pricked site, and the blood collection is finished.

This process takes less than five minutes.

What should I expect after my Blood Culture Test?

Once the phlebotomist has collected the blood sample, it will be sent to the laboratory for processing or testing. When the reports are ready, your healthcare provider will share the results with you.

What are the risks of a Blood Culture Test?

These blood tests are common and don’t carry any significant risks. You might have a slight pain like an ant bite when the needle gets inserted, and a small bruise can develop there.

When can I expect my Blood Culture Test results?

At Orange Health, blood culture test reports are available within 8 days.

What do the results of a Blood Culture Test mean?

If the blood culture is positive, it can mean that there is a bacterial or fungal infection in the bloodstream that needs to be treated immediately. These infections can be life-threatening, especially in patients whose immune systems are not working properly. The doctor may start the treatment with a broad spectrum of antibiotics, often given intravenously while waiting for the test results, and will adjust the treatment depending upon the antibiotic susceptibility results.

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A positive result could also be a false positive caused by skin contamination. If two or more blood culture sets are positive for the same bacteria, it is more likely that the bacteria found in the culture are causing the infection. If one set is positive and the other set is negative, this could be either an infection or contamination. The doctor will need to evaluate the clinical significance of the patient and the type of bacteria found.

If the two sets of blood culture sets are negative, the probability of the infection being caused by the bacteria or yeast is low. However, if the symptoms persist, for example, a fever that does not go away, additional tests may be required. Reasons that the symptoms can not resolve even though blood culture results are negative include:

1. Some of the microorganisms are difficult to grow in culture. Additional blood cultures using special nutrient media can be done to try to grow and identify the pathogens. 
2. The viruses cannot be detected using blood culture bottles designed to grow bacteria. If the doctor suspects that a viral infection could be the cause of the person’s symptoms, then other laboratory tests would need to be performed as well. The tests would depend on the clinical signs and the type of the virus the doctor suspects is causing the infection

What are normal Blood Culture Test results?

Most of the bacteria may be seen in culture in 2 to 3 days. But some types of bacteria can take 10 days or longer to show up. Fungus can take up to 30 days to show up in the culture.

Normal: No bacteria or fungus was found. Normal culture results are called negative.

Abnormal: Bacteria or fungus growing in the culture. Abnormal culture results are called positive.

If bacteria are found in the culture, another test is often done to find the best antibiotic susceptibility test that will guide in killing of the bacteria. This is called sensitivity or susceptibility testing. Sensitivity testing is very important so the blood infection is treated correctly. It also helps prevent bacteria from becoming resistant to antibiotics. 

What other tests might I have along with this test?

Complete Haemogram, CRP, and urine culture.

How do I book a Blood Culture Test at home?

Log on to www.orangehealth.in and submit your details. Our highly trained, professional, and vaccinated eMedics will be at your doorstep within 60 minutes or at the time booked by you.

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