How is Chlamydia Infection get tested and diagnosed?
Date:2018-12-06 click:0
Chlamydia tests use a sample of body fluid or urine to see whetherchlamydia 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 quick test finds substances (chlamydia antigens) that trigger the immune system to fight chlamydia infection.
· Direct fluorescent antibody test (DFA). This 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.
The diagnosis of genital chlamydial infections evolved rapidly from the 1990s through 2006. Nucleic acid amplification tests (NAAT), such as polymerase chain reaction (PCR),transcription mediated amplification (TMA), and the DNA strand displacement amplification (SDA) now are the mainstays. NAAT for chlamydia may be performed on swab specimens collected from the cervix (women) or urethra (men), on self-collected vaginal swabs, or on voided urine. Urine and self-collected swab testing facilitates the performance of screening tests in settings where genital examination is impractical. At present, the NAATs have regulatory approval only for testing urogenital specimens, although rapidly evolving research indicates that they may give reliable results on rectal specimens.
Because of improved test accuracy, ease of specimen management, convenience in specimen management, and ease of screening sexually active men and women, the NAATs have largely replaced culture, the historic gold standard for chlamydia diagnosis, and the non-amplified probe tests. The latter test is relatively insensitive, successfully detecting only 60-80% of infections in asymptomatic women, and often giving falsely positive results. Culture remains useful in selected circumstances and is currently the only assay approved for testing non-genital specimens.
