WHAT IS CHLAMYDIA SCREENING TEST?
Chlamydia is intracellular parasites with the characteristics of bacteria and of viruses that cause psittacosis, pneumonia, eye infections, and lymphogranuloma venereum. C. trachomatis infection in the lower genital tract of women causes mucopurulent cervicitis and can lead to pelvic inflammatory disease, tubal occlusion, infertility, and, rarely, lymphogranuloma venereum. It can also be passed on to an infant via direct contact with the mother’s cervix during birth, and cause neonatal infections such as conjunctivitis and pneumonia. In men, genital tract infection with Chlamydia causes urethritis and epididymitis. The tests that are most commonly used for screening and diagnosis of Chlamydia trachomatis infections are:
- Urine nucleic acid amplification test, which has the highest sensitivity (82-100% for a urine sample), but is expensive.
- Less sensitive (75%-80%) is an enzyme-linked immunosorbent assay (ELISA) performed on a cervical or urethral swab, or urine sample.
- A DNA probe from cervical or urethral swabs is more commonly used in inpatient settings for C. trachomatis detection.
- Testing a urine dipstick for leukocyte esterase can be used for urethritis in males, but a positive result must be confirmed by any of the more specific tests (see Urinalysis—Urine) because this test is prone to false positive results.
- Direct fluorescent antibody (DFA) testing may also be done on either a cervical or urethral swab or urine sample. DFA is expensive, but has high specificity (~88%) and provides rapid results; thus, it can be used to confirm other less specific findings, such as the leukocyte esterase test or ELISA.
- Point-of-care Chlamydia testing is also available, but has lower sensitivity (52%-85%, depending on the brand) than the nucleic acid amplification test and is more expensive. However, compliance with repeat testing is higher because this test can be done at home. It is recommended that women undergoing treatment be re-tested after 3 months to detect re-infection from an infected partner.