A blood culture test today has become an essential investigative tool for doctors to conclude the presence a possible infection in the blood. Hence it is important to understand what is blood culture and why do we need the test. When our body shows symptoms of infection possibly due to external microorganisms like bacteria and fungus, doctors generally order for the test.
what is detected from the blood culture test?
Blood in our body is very much sterile and does not have any bacteria or fungus. But if there is a presence of bacteria in the blood due to any external factors, it could cause complications. The bacteria in the blood could make the immune system weak and affect other organs in the body. When the patients show symptoms of a possible infection the doctor orders for a blood culture test. The types of bacteria found in blood culture can be both gram positive and gram negative. The former includes organisms like Staphylococcus, Streptococcus, and Enterococcus species. While the common form of gram-negative bacteria found in blood culture is E.coli.
why do i need the test?
Sometimes there are chances that microorganisms like bacteria enter your bloodstream and cause what is known as a systemic infection. It becomes imperative to undergo a blood culture test in order to find out its severity. Symptoms that could force your doctor to order for the test include
• Increase in heart rate and breathing
• Fever and chill in the body
• A decrease in frequency of passing urine
There are certain serious symptoms that might show if you are suffering from a bacterial infection in blood like there could be an alarming drop in blood pressure or you could notice inflammation in some or your body parts. Sometimes the infection can also lead to organ failure. Hence it is very important for the patient to undergo the test in order to figure out the options for treatment.
how is a blood culture performed?
The blood culture procedure is generally performed in a hospital or at a diagnostic centre. The nurse or a technician present there is required to clean up the area 70% isopropyl alcohol where the needle is to be inserted. This is done to keep the area sterile, as microorganisms present on the surface could alter the test results. Once this is done an elastic band is warped tightly on to your arm. This leads to increased visibility of the veins due to more blood flowing in them. The technician then uses a needle to draw samples from your blood. Depending upon the nature of the test sometimes multiple samples are also drawn. Samples of the blood culture test procedure are then submitted to the laboratory where they are cultured.
aerobic and the anaerobic blood culture
Generally, for a blood culture lab test samples have to be inoculated in two bottles. These are known as anaerobic and aerobic blood culture containing specific media for each. When the sample is collected, it is mandatory that the aerobic bottle is inoculated first. This is done in order to avoid the release of any air from the syringe into the anaerobic culture which is taken next. 10ml of blood is required to be collected in each blood culture. For differentiation, the aerobic bottles have a blue cap while the anaerobic ones have a violet cap.
how to interpret test results?
Once the tests are accomplished your technician prepares the reports reflecting your test results. The blood culture report is considered negative if there is no growth of pathogens in both the cultures. While a positive blood culture signifies that there are microorganisms present that could be causing infection in your blood. It is important that both the blood culture results are positive to have conclusive evidence of infection. Also sometimes the symptoms still persist inpatient even if the blood culture test report is negative. In such circumstances the doctor orders for advanced tests like;
1. Urine or Sputum Culture: A positive result of the same indicates a possible source of infection.
2. A CSF analysis can also be conducted to detect the presence of infection in the body.
3. CBC or complete blood count: Infection could be detected if there is an increase in white blood cell count.
why do the blood culture results take so long?
The blood culture tests are conducted to detect the presence of bacteria, fungus and viruses. For the test to show positive results a sufficient amount of growth is required before the microorganisms can be detected. Hence sufficient time is required to grow quantities that can be detected.
what is blood culture test for and how much do they cost?
A blood culture test is carried out to detect the presence of microorganisms in the blood like bacteria and fungus. The blood culture test cost is generally variable and depends upon a number of factors like the hospital and city where the test is conducted. There might be variations in the cost of the test hence it is advisable that you inquire about the blood culture test price before going in for the test at a hospital or diagnostic centre.
A blood culture test is an important diagnostic tool hence should be carried out with the utmost precaution. Let your technician known if you have had an antibiotic before the test. Also, ensure that the samples are processed correctly without any exposure to bacteria or fungus on the skin.