infections
Diagnosis of Infectious Disease
Samples for Testing
A sample is taken from an area of the person's body likely to contain the microorganism suspected of causing the infection. Samples may include Blood Sputum Urine Stool Tissue Cerebrospinal fluid Mucus from the nose, throat, or genital area Some samples sent for testing, such as sputum, stool, and mucus from the nose or throat, normally contain many types of bacteria that do not cause disease. Doctors need to distinguish between these bacteria and those that could cause the person's illness. Other samples come from areas that normally do not contain any microorganisms (that are sterile), such as urine, blood, or cerebrospinal fluid (the fluid that surrounds the brain and spinal cord). Finding any bacteria in such samples is abnormal as long as the area from which the sample was taken was first cleaned with an antiseptic to prevent contamination. 