A blood sample is needed. Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood. Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding. In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding. It is very important that the blood sample does not become contaminated. The sample is sent to a laboratory where it is placed in a special dish and watched to see if microorganisms grow. This is called a culture. Most cultures check for bacteria. If bacteria does grow, further tests will be done to identify the specific type. A gram stain may also be done. Gram stain is a method of identifying microorganisms (bacteria) using a special series of stains (colors). For example, see: skin lesion gram stain. | 
Tests
