STD : THE TESTS FOR CHLAMYDIA
There are several ways to test for chlamydia. Which method is appropriate for you depends on a number of factors, including which tests are handled routinely by the laboratory in your area, the cost of the tests, and which test your health care provider prefers. None of the tests is 100 percent accurate; accuracy can be affected by how well the specimen is stored on its way to the laboratory and the skill of the provider in collecting the specimen, among other factors.
The oldest way to test for chlamydia is to culture for it—that is, to rub a suspected infected area with a swab and try to grow the chlamydia in a special solution. Chlamydia is hard to grow in solution, however, so this test may have low accuracy. Other tests, called “non-culture tests,” were subsequently developed that looked either directly for proteins from the surface of the chlamydia (enzyme-linked immunosorbent assay [ELISA] and direct fluorescent-antibody assay [DFA]), or indirectly for the genetic material of the chlamydia (DNA probes). Yet these tests also missed many people who were infected.
Newer tests, the polymerase chain reaction and the ligase chain reaction (PCR and LCR, respectively), look directly for the genetic material of the bacterium and have over 90 percent accuracy, far better than that of the other tests. (This means that the test correctly identifies 90 out of 100 people who are infected.) The LCR can be performed from either swabs or urine in both men and women. These tests have now become the tests of choice in detecting genital chlamydia infection in men and women. For throat or anal chlamydia, however, culture is still the preferred test. The conjunctiva can be tested using the nonculture tests (ELISA, DFA, and DNA assays). Blood tests that look for antibodies, or the body’s immune response to previous infection with chlamydia, result in a positive test.
When someone is found to have chlamydia, decisions about what kind of medication is to be used, how long it is to be used, and what land of follow-up is necessary depend on the extent of the infection. In order to determine the extent of the infection, a physical examination is needed in addition to the screening test. For women, a pelvic examination must be done as part of the screening. Some women may test positive for chlamydia and have no evidence of infection on examination, whereas others have cervicitis or PID. In men who test positive for chlamydia, an examination may show no evidence of infection, or there may be signs of urethritis, epididymitis, or prostatitis.
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