Chlamydia Serology Test in Arizona

What this test measures

Chlamydia is a common bacterial sexually transmitted infection caused by Chlamydia trachomatis. Standard screening for genital infection uses nucleic acid amplification on a urine or swab sample. A blood test instead looks for antibodies, which are proteins the immune system makes after encountering the bacterium. This approach can be used when clinicians want to assess a possible infection at a site that is harder to sample directly.

The test measures antibody levels in serum, often reporting IgG and sometimes IgA or IgM. Antibody tests can show that the immune system has responded to chlamydia at some point, but they do not reliably distinguish a current infection from a past one, and they are not the preferred method for routine genital screening. The sample is a standard blood draw.

Because of these limits, results are interpreted carefully. A positive antibody result suggests exposure or infection at some point, while a negative result does not rule out an infection, especially a recent one. A qualified healthcare provider decides whether additional or more specific testing, such as nucleic acid testing, is needed.