Why are blood cultures drawn from two different sites?

To increase the chances of detecting a bloodstream infection.

When a person has a bloodstream infection, the bacteria or other microorganisms that are causing the infection are present in the blood. However, the concentration of these microorganisms in the blood can be very low, making it difficult to detect them.

By drawing blood cultures from two different sites, the chances of detecting the microorganisms are increased. This is because it is possible that the microorganisms may be present in one of the blood cultures, but not in the other.

In addition, drawing blood cultures from two different sites can help to identify the source of the infection. For example, if the blood cultures from one site are positive for bacteria, while the blood cultures from the other site are negative, this may indicate that the infection is localized to the area where the positive blood cultures were drawn.