Chlamydia Tests

Chlamydia tests use a sample of body fluid or urine to see whether chlamydia bacteria (Chlamydia trachomatis) are present and causing an infection. Chlamydia is the most common bacterial sexually transmitted disease (STD) in the United States.

Several types of tests can be used to find a chlamydia infection. Most tests use a sample of body fluid from the affected area.

• Nucleic acid amplification tests (NAAT). These tests find the genetic material (DNA) of chlamydia bacteria. These tests are the most sensitive tests available. This means they are very accurate and that they are very unlikely to have false-positive test results. A polymerase chain reaction (PCR) test is an example of a nucleic acid amplification test. This test can also be done on a urine sample.
• Nucleic acid hybridization tests (DNA probe test). A probe test also finds chlamydia DNA. A probe test is very accurate but is not as sensitive as nucleic acid amplification tests.
• Enzyme-linked immunosorbent assay (ELISA, EIA). This common, quick test finds substances (chlamydia antigens) that trigger the immune system to fight chlamydia infection.
• Direct fluorescent antibody test (DFA). This common, quick test also finds chlamydia antigens.
• Chlamydia culture. A culture is a special cup that allows the chlamydia bacteria to grow. This test is more expensive and the results take longer (5 to 7 days) than the other tests. The culture must be done in a lab. The chlamydia culture test may be done when child sexual abuse is suspected or when treatment for infection has not worked.