Culture, Blood

The Culture, Blood test contains 1 test with 3 biomarkers.

Brief Description: A blood culture test is a diagnostic procedure that involves culturing a sample of blood to detect the presence of bacteria, fungi, or other microorganisms causing infections in the bloodstream. The test helps identify the specific pathogen causing the infection and guides appropriate treatment.

Also Known As: Blood Culture Test, Blood, Blood Bacteria Test, Bacterial Blood Test, Fungal Blood Test, Blood Fungi Test, Sepsis Test

Collection Method: Blood Draw

Specimen Type: Whole Blood

Test Preparation: No preparation required

Average Processing Time: 6 to 7 days, however a positive culture can take up to 30 days

Important: Aerobic culture, anaerobic culture. If culture is positive, identification will be performed at an additional charge (CPT code(s): 87076 or 87106 or 87077 or 87140 or 87143 or 87147 or 87149).
Antibiotic susceptibilities are only performed when appropriate (CPT code(s): 87181 or 87184 or 87185 or 87186).

When is a Blood Culture test ordered?

When a patient exhibits sepsis symptoms, which show that bacteria or their toxic byproducts are harming the body, a healthcare professional may order blood cultures.

Drawing blood cultures might be suitable when symptoms are present in patients who are at a higher risk of developing a systemic infection due to previous infections, surgeries, prosthetic heart valve replacements, or immunosuppressive medication. Blood cultures are taken more frequently from babies and young children since they may have an infection but not always display the classic sepsis symptoms.

What does a Blood Culture test check for?

Blood cultures are techniques used to find the source of an illness in the blood and detect it. Although viruses, yeasts, and other fungi as well as bacteria can potentially cause bloodstream infections, they are less prevalent. This article concentrates on the use of blood cultures to find and identify bacteria in the blood, though blood can also be used to test for viruses.

When a person has a serious infection and/or the immune system is unable to contain it at its source, a blood infection often develops from another specific spot within the body. For instance, a urinary tract infection may spread from the bladder and/or kidneys into the circulation, travel throughout the body, infect other organs, and result in a serious and occasionally fatal systemic infection. Sometimes, the terms septicemia and sepsis are used synonymously to refer to this condition. While sepsis is the body's acute, overpowering, and occasionally lethal response to infection, septicemia refers to an infection of the blood. This ailment frequently need for quick and vigorous care, usually in a hospital's critical care unit.

The infection of the blood can lead to more severe consequences. A bloodstream infection may lead to endocarditis, an inflammation and infection of the heart's lining and/or heart valves. Although these infections are uncommon, patients with artificial heart valves or joints are more likely to develop systemic infections after surgery.

Blood infections are more common in people whose immune systems are compromised by underlying illnesses like leukemia or HIV/AIDS or by immunosuppressive medications used in chemotherapy. These people are more likely to contract blood infections because their immune systems are less able to destroy the microorganisms that occasionally enter the blood. Through the use of intravenous drugs, intravenous catheters, or surgical drains, bacteria and yeasts can also enter the circulation directly.

Before they are declared as negative, blood cultures are cultured for a number of days. If originally present in low numbers, some species of bacteria and fungi may develop more slowly than others and/or take longer to be discovered.

A blood culture that is positive identifies the exact bacteria that is infecting the patient, and susceptibility testing is done to determine which drugs are most likely to be helpful in treating the illness.

The blood culture testing procedure is automated, and devices continuously check the samples for bacterial or fungal development. This enables prompt results reporting and enables the medical professional to target antimicrobial medication specifically at the particular bacteria found in the blood. While awaiting the results of a blood culture, broad-spectrum antimicrobials are typically administered intravenously because therapy must be started as soon as feasible in situations of sepsis. Once the bacteria responsible for the infection is discovered, antimicrobial medication may be switched out for a more focused antibiotic therapy.

Lab Tests often ordered with a Blood Culture test:

When a Blood Culture test is ordered, it's often part of a broader evaluation to identify the infectious agent and assess the severity of the infection. Here are some tests commonly ordered alongside it:

1. Complete Blood Count (CBC) with Differential:

   • Purpose: To evaluate overall blood health, including the number and types of white blood cells, red blood cells, and platelets.
   • Why Is It Ordered: To check for signs of infection or anemia. An elevated white blood cell count is a common indicator of infection.

2. C-Reactive Protein (CRP) or High-Sensitivity C-Reactive Protein (hs-CRP):

   • Purpose: To measure CRP, a protein that increases in response to inflammation.
   • Why Is It Ordered: To assess the level of inflammation and monitor the severity of the infection.

3. Erythrocyte Sedimentation Rate (ESR):

   • Purpose: To measure the rate at which red blood cells settle in a tube over a specified period, an indirect measure of inflammation.
   • Why Is It Ordered: Like CRP, to assess inflammation associated with infection.

4. Procalcitonin:

   • Purpose: To measure levels of procalcitonin, a substance produced in response to bacterial infection.
   • Why Is It Ordered: To differentiate bacterial infections from other causes of inflammation and to guide antibiotic therapy.

5. Urinalysis and Urine Culture:

   • Purpose: To analyze components of the urine and to test for the presence of bacteria or fungi in the urinary tract.
   • Why Is It Ordered: To determine if the infection is related to the urinary tract, a common source of bloodstream infections.

6. Liver Function Test:

   • Purpose: To assess liver health.
   • Why Is It Ordered: To evaluate liver function, which can be affected by systemic infection and sepsis.

7. Kidney Function Test:

   • Purpose: To evaluate kidney function.
   • Why Is It Ordered: To monitor kidney health, as infections can lead to renal impairment, especially in sepsis.

8. Lactic Acid:

   • Purpose: To measure the level of lactic acid in the blood.
   • Why Is It Ordered: Elevated lactic acid can be a sign of sepsis and tissue hypoperfusion.

These tests, when ordered alongside a Blood Culture test, provide a comprehensive evaluation of a patient with suspected systemic infection or sepsis. They are crucial for identifying the source and severity of the infection, guiding appropriate antibiotic or antifungal therapy, and monitoring the patient’s response to treatment. The specific combination of tests will depend on the individual’s symptoms, clinical findings, and risk factors.

Conditions where a Blood Culture test is recommended:

• Sepsis: This life-threatening condition occurs when the body's response to an infection becomes uncontrolled and can lead to organ failure.
• Endocarditis: An infection of the heart's inner lining and valves.
• Bacteremia and Fungemia: Presence of bacteria or fungi in the bloodstream.
• Bone and Joint Infections: Infections that spread to bones or joints.

How is this test used by my health care provider?

Blood cultures are used to determine the type of bacteria or fungi present, detect their presence in the blood, and direct treatment. A blood infection that can cause sepsis, a dangerous and potentially fatal consequence, is detected by testing. Testing is frequently carried out in a hospital setting because patients with suspected blood infections are frequently treated in intensive care units.

This article concentrates on the use of blood cultures to identify and detect bacteria, while blood samples may be used to detect viruses as well.

Additional related tests that might be carried out include:

Gram stain, a fast test for determining the sort of bacteria in question,

Testing for susceptibility identifies the medication that might be most successful at treating the infection.

The blood culture is frequently followed by a request for a complete blood count to see if the patient has an elevated white blood cell count, a sign of a possible infection. Sometimes additional testing is carried out, such as a chemistry panel to assess an individual's organ condition or a urine culture to assist in determining the origin of the initial illness. This is especially true if a person exhibits signs of a meningitis, pneumonia, or urinary tract infection.

What do my Blood Culture test results mean?

The presence of the same bacteria or fungi in two or more blood cultures indicates that the person being examined most likely has a blood infection with that microbe. The exact bacteria or fungi that are causing the infection are usually identified in the results.

Blood infections are dangerous conditions that require prompt treatment, frequently in a hospital. Sepsis is a complication that poses a serious risk to life, particularly in those with compromised immune systems. While awaiting the results of the blood culture or susceptibility testing, medical professionals who suspect sepsis may start patients on intravenous broad spectrum antibiotics that are efficient against a variety of bacteria. A more targeted antimicrobial agent for the bacteria or fungi found in the blood cultures may be used as treatment once the results are available.

A skin contaminant or infection may be present if one blood culture set is positive and the other is negative. Before making a diagnosis, the medical professional will take into account the patient's clinical condition and the type of bacteria or fungi discovered. In this instance, more testing might also be necessary.

After several days, blood culture sets that are negative indicate that there is a low likelihood that the patient has a blood illness brought on by bacteria or fungi. Additional testing, however, might be necessary if symptoms linger, including a fever that won't go away. Symptoms may persist despite negative blood culture results for a number of reasons, including

It may be necessary to perform additional blood cultures using specialized nutrient media in order to attempt and grow and identify the pathogen because some microorganisms are more difficult to grow in culture.

Blood culture bottles made to grow bacteria cannot be used to detect viruses. Additional laboratory testing would need to be carried out if the medical professional believes that the patient's symptoms could be due to a viral infection. Depending on the patient's clinical symptoms and the type of virus the doctor believes is the cause of the illness, certain tests may be prescribed.

Even though blood cultures are negative, sepsis may still be present based on the results of further tests that may be performed in conjunction with blood cultures. Some of them could be:

• thorough blood count. An infection may be indicated by an elevated white blood cell count.
• Complement. The concentration of C3 can rise.
• An infection source that may have moved to the blood may be identified by a positive urine or sputum culture.

An examination of the CSF could point to the infection's origin.

Most Common Questions About the Blood Culture test:

Clinical Utility and Interpretation

What is the Blood Culture test, and why is it performed?

The Blood Culture test is a laboratory examination used to detect the presence of bacteria or fungi in the blood. It helps identify the specific microorganism causing an infection (sepsis) and can be crucial for guiding appropriate antimicrobial therapy. The test is typically performed when a patient exhibits symptoms of a systemic infection, such as fever, chills, or low blood pressure.

How are the results of the Blood Culture test interpreted?

Interpretation of the Blood Culture test requires careful consideration of clinical symptoms, patient history, and other laboratory findings. A positive result indicates the presence of an infection in the blood, while a negative result may mean no infection or a failure to detect it. The identified organism's sensitivity to antibiotics is also usually tested to guide treatment.

Clinical Applications and Diagnoses

When is the Blood Culture test typically ordered?

The Blood Culture test is often ordered when a healthcare provider suspects a patient may have a systemic or bloodstream infection, particularly in cases of unexplained fever, chills, rapid heart rate, or low blood pressure. It is also utilized in monitoring known infections or post-surgical complications.

What can the Blood Culture test tell about the infection's source?

While the Blood Culture test is primarily used to detect the presence of an infection in the blood, it may also provide clues about the source of the infection. The type of bacteria or fungi identified can hint at where the infection originated, such as the urinary tract, lungs, or heart valves.

Comparative Insights

How does the Blood Culture test compare to other tests for detecting infections?

The Blood Culture test is unique in its ability to identify the presence of live microorganisms within the blood. Unlike other tests that may detect antibodies or antigens, the Blood Culture test allows for the isolation and identification of the actual causative agent. This distinction enables specific antimicrobial sensitivity testing and more targeted treatment.

Understanding Limitations and Challenges

What are some of the limitations of the Blood Culture test?

The Blood Culture test may have limitations related to the timing of the sample collection, volume of blood drawn, and the presence of antimicrobial agents in the blood. In some cases, a single test may not be sufficient, and multiple cultures may be necessary to detect intermittent bacteremia. False-negative results may occur if the blood sample is not handled or processed correctly.

How can contamination affect the Blood Culture test results?

Contamination is a notable challenge in the Blood Culture test. If skin bacteria contaminate the blood sample during collection, it may lead to false-positive results. Proper collection techniques and aseptic handling are crucial to minimize this risk.

Additional Questions and Insights

What role does the Blood Culture test play in antimicrobial stewardship?

The Blood Culture test plays a vital role in antimicrobial stewardship by identifying the specific microorganisms responsible for an infection. This identification, coupled with sensitivity testing, allows healthcare providers to choose the most appropriate and targeted antibiotic therapy, minimizing unnecessary broad-spectrum antibiotic use.

How might the Blood Culture test results impact patient management and treatment?

The results of the Blood Culture test directly influence patient management by guiding the selection of appropriate antibiotics. Positive results may necessitate aggressive treatment, hospitalization, or even admission to an intensive care unit. A negative result might lead to de-escalation or cessation of empirical antimicrobial therapy.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.