BLOOD CULTURE

A Culturing Blood is a laboratory test that helps to determine the existence of microorganisms like bacteria and fungi in the circulating blood. This is commonly performed for patients with serious infections, like sepsis, which is a medical condition with potential to be fatal. Infection can lead to sepsis or septicaemia, a medically dangerous situation where infection spreads throughout the body, requiring immediate medical attention. 

In blood culturing, the health professional draws blood from a patient and sends it to laboratory where it is kept in special containers for a specific time where any microorganisms present would multiply. Labs check for a variety of growth of microorganisms (bacteria, fungi) after some incubation period. 

Blood culture results assist in: 

• Analysing which microorganism is causing the infection.  
• Determining the appropriate therapeutic regimen which could be either antibiotics or antifungal medications.  
• Evaluating the severity of the infection and assisting the physician in managing the patient’s condition.

The Blood Culture checks for the specific pathogenic microorganisms such as bacteria and fungi, within the blood stream. It also measures: 

• Microorganism type: The bacteria or fungi causing the infection.  
• Antimicrobial susceptibility: Determines which antibiotics will most effectively treat the infection through a lab test and compares the cultured microorganisms to a range of different medicines.  
• Severity of infection: A higher quantity of microorganism's present (colony count) may suggest greater severity of infection. 

The following scenarios target the use of blood cultures and are taken at the following specific times:  

• Signs of severe infection: When a patient shows signs of sepsis or other forms of systemic infection such as fever, and chills or body temperature changes, change in pulse rate, confusion, and/or low blood pressure.  
• Possibility of bloodstream infection: Such patients who are in a group of high risks for infections, those with weakened immunity, chronic, and patients with invasive devices like catheters or ventilators may also be at a higher risk. 
• Unexplained Fever: For patients with no apparent source for their high fever, a blood culture may be helpful to determine if an underlying infection exists. 
• Monitoring Existing Infection: A blood culture may be performed to evaluate whether infection has been adequately managed and treatment has cleared infection. 

• Risks:  
• Minimal Risk: Blood cultures are performed like any other blood draw. As such, there is a minor risk of bruising, discomfort, or infection of the skin over the needle’s entrance.  
• Multiple Blood Draws: Sometimes more than one sample is needed for complete testing. This is especially true for patients with septicaemia who are often very difficult to diagnose. 
• Limitations:  
• False Negative Results: Blood cultures may fail to identify the microorganism responsible for the infection. This is especially true if the infection is localized and not systemic, meaning it confined to the blood. 
• Results Not Available Immediately: Results from cultures are not available immediately as they take time to process. Most procedures aside from culture require waiting 24–48 hours. Some cases are straightforward and require only rapid or molecular diagnostic tests. 
• Contamination: Sample collection poses a risk of contamination leading to false positive results. 

While performing a blood culture, the following components are analysed: 

• Microorganism growth: The test checks for the existence of bacteria or fungi growth in the blood sample. 
• Microbial identification: After organisms grow, they are identified to see what pathogen is causing the infection. 
• Antibiotic susceptibility: Bacteria or fungi from the culture are infected with an Antibiotic to see which one of them will treat sore best. 
• Infection load: How the number of colonies grown can indicate the severity of the infection. 

Blood Cultures is specifically indicated for: 

• Patients with signs of sepsis: Patients who present with fever, chills, tachycardia, altered mental status and other features of a severe infection. 
• Patients with some chronic condition: Immunosuppressed patients (like those with cancer, organ transplant) or those with chronic conditions (like diabetes) or even those with invasive medical devices. 
• Fever of unknown origin: When a person has a high fever of unknown origin, carrying out a blood culture may help identify the source of infection. 
• Monitoring ongoing infections: Some patients with infections, such as those undergoing treatment for bloodstream infections, need repeat blood cultures to monitor infection clearance. 

Blood culture possesses important advantages in improving one's health, such as;  

• Accurate diagnosis: Guarantees precise identification of the suspected pathogen thereby making accurate diagnosis and treatment. 
• Guiding treatment: Blood culture combined with misuse of antifungal or antibacterial agents enables modification of treatment for better results thus improving the prognosis. 
• Early detection of sepsis: Use of blood culture becomes very important in identifying potentially dangerous infections, such as sepsis, so that treatment can be initiated without delay. 
• Monitoring progress: In those patients on treatment, blood culture can assess the efficacy of antibiotics or antifungals in eliminating the infection from the bloodstream. 

The Blood culture tests is mostly done on patients suffering from bloodstream infections which include the following:  

• Sepsis: This refers to a life-threatening infection that may spread unto all other regions of the body and subsequently leads to organ failure.  
• Bacteraemia: Now this is most used in reference to a condition where individuals are infected with living bacteria, presenting English-Hindi Dictionary translations.  
• Fungal infections: Cultures are also useful in identifying infections caused by viruses, more so in those with weaker body immunity.  
• Endocarditis: This is a disease of heart valves infective in origin, usually due to bacteria which may have come from some other region of the body through the veins. 

While blood culture tests do not require any special instructions, recent use of antimicrobials can certainly change the result so the correct explanation should be given to the physician.  

Prerequisites for the Blood Culture Test 

The patient is expected to submit a blood specimen. It is often obtained through normal venipuncture; in some situations, blood is collected from a catheter or infection site. 

Eligibility for Blood Culture Testing 

This test is generally conducted on patients who are experiencing symptoms of severe infection or those with a high likelihood of having a bloodstream infection. 

Blood Culture Test Administration Steps 

A sterile area will be prepped by the health worker, then having a needle inserted into one of the veins. The sample will be sent to the lab for microbial growth and testing. 

Caution Before for Taking the Blood Culture Test 

Providing any kind of antibiotic can change the effectiveness for patients undergoing the test therefore it should be communicated to the doctor. Furthermore, informing the doctor about allergies and pregnancy is equally important.