Blood Culture test

A blood culture test is recommended when the following symptoms of sepsis are observed in the body:

• Rapid breathing rate
• Confusion
• High fever
• Low blood pressure
• Nausea
• Chills
• Reduced urination frequency

Severe symptoms of sepsis include

• An extreme drop in the blood pressure
• One or more organ failures
• Small blood clots in the smallest blood vessels of the body
• Inflammation in the entire body

This test identifies infection-causing bacteria and helps determine the best treatment procedure to combat the infection. Two or three blood samples might be tested to ensure that the fungi or bacteria do not remain undetected.

There are no special preparations required before going for a blood culture test.

Blood culture test is a simple procedure, in which a lab technician would draw a blood sample drawn from your vein (usually arm) after swabbing your skin with an appropriate antiseptic solution. The blood sample is then added to bottles that contain a culture broth to allow the organisms, if present, to grow.

Immediately after the first sample collection, a second blood sample is collected from a different vein in the body. Normally, more than one blood sample is collected from different veins in the body to increase the chances of detecting disease-causing organisms. These cultures are then tested in laboratories to detect the organisms. Gram staining might be performed to identify bacterial strains.

The amount of blood collected from young children and infants is lesser and is decided according to their body weight. In children, a single blood sample is collected as their blood contains a high concentration of bacteria or infection causing organism.

Even though it is a low-risk procedure, the following are some rare problems that might occur while withdrawing blood samples:

• Light-headedness or fainting
• Infection if the skin tears
• Many punctures to locate the appropriate veins
• Excessive Bleeding 
• Haematoma (accumulation of blood under the skin)

Normal results: A normal blood culture test results indicate the absence of germs in blood sample. Blood cultures that produce negative results after many days indicate that the probability of blood infection is low. Additional tests may be recommended if symptoms of infection persist.

Abnormal results: Abnormal blood culture test results indicate bacteraemia or presence of organisms in the sample.

If two or more blood culture samples contain the same fungi or bacteria, it indicates that the blood infection is caused due to that particular organism.

If one blood culture sample has negative results and the other sample has positive results, it denotes that infection might be present or that the samples are contaminated. Before making a diagnosis of the infection, a doctor considers the person’s clinical condition along with the type of organism detected in test results.

Other tests that might be recommended along with blood culture test to confirm the results of blood culture samples include:

• Complete blood count (CBC)
• Sputum culture
• Urine culture
• Cerebrospinal fluid analysis

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. This information is purely from an educational perspective and is in no way a substitute for medical advice from a qualified doctor.