What are the tests for infection in the blood?

Blood Culture. A suspicion that infection is in the blood can be confirmed by taking a blood specimen and submitting it to the lab for culture. In the lab, blood is transferred to a nutrient media, like planting seeds in a garden, and monitored over several days for signs of growth. If the material becomes hazy, a small amount is examined under a microscope. If they see germs they have confirmed it.