The primary way to test for a blood infection is through a blood culture.
What is a Blood Culture?
A blood culture is a laboratory test that identifies the presence of bacteria or fungi in a blood sample. A blood infection, also known as bacteremia or septicemia (when severe), often occurs alongside other serious infections. These infections may originate in areas such as the:
- Lungs
- Kidneys
- Bowels
- Gallbladder
- Heart valves
Individuals with weakened immune systems are also more susceptible to developing blood infections.
How is a Blood Culture Performed?
- Sample Collection: A healthcare provider will draw a blood sample, usually from a vein in your arm. Multiple samples might be taken from different sites to increase the accuracy of the test.
- Sterilization: The skin is thoroughly cleaned with an antiseptic before the blood is drawn to minimize the risk of contamination.
- Incubation: The blood sample is then placed in a special bottle containing a nutrient-rich broth designed to promote the growth of microorganisms. This bottle is incubated for a period of time, typically several days.
- Monitoring: The laboratory monitors the bottle for signs of microbial growth.
- Identification: If microorganisms are detected, they are identified to determine the specific type of bacteria or fungi causing the infection.
- Sensitivity Testing: Once the microorganism is identified, sensitivity testing is performed to determine which antibiotics will be most effective in treating the infection.
Why is Blood Culture Testing Important?
- Diagnosis: Confirms the presence of a blood infection.
- Identification: Determines the specific microorganism responsible for the infection.
- Treatment Guidance: Guides the selection of appropriate antibiotics or antifungal medications.
- Monitoring: Helps monitor the effectiveness of treatment.
Other Tests That Might Be Performed
While blood cultures are the primary test, other tests might be performed to assess the severity of the infection and identify the source:
- Complete Blood Count (CBC): Checks for signs of infection, such as an elevated white blood cell count.
- Comprehensive Metabolic Panel (CMP): Evaluates organ function and electrolyte balance.
- Lactate Level: Elevated lactate levels can indicate sepsis.
- Procalcitonin Level: A marker that increases significantly during bacterial infections.
- Imaging Studies: X-rays, CT scans, or ultrasounds may be used to identify the source of the infection.
