Everything About Chlamydia and Chlamydia Testing

Chlamydia is a bacterial sexually transmitted disease that is caused by Chlamydia trachomatis. It is a common STD that is contracted during vaginal, anal or oral sex. Chlamydia can also be spread by sharing unclean sex toys. The Centers for Disease Control and Prevention (CDC) estimates that there are approximately 2.86 million chlamydia infections annually, making it the most frequently reported bacterial STD in the U.S.

Often, people with chlamydia do not show any signs or symptoms of the infection. Therefore, chlamydia can be spread easily, since chlamydia carriers typically do not realize they have it. Which is why getting tested for chlamydia is so important. If symptoms appear, they typically occur within 2-21 days after exposure.

Chlamydia most frequently infects the cervix, urethra, or rectum, but it can also be spread to the throat during oral sex. The infection can spread to the eye if an infected area is touched and then the eye is touched. Pregnant women with chlamydia can pass the infection to their babies during childbirth. Chlamydia is especially harmful to infants and can cause infections that result in pneumonia and even blindness.

Symptoms of chlamydia sometimes differ between men and women.

Symptoms in men can include:

  • Discharge from the penis
  • Burning/itching sensation during urination
  • Pain/swelling in one or both testicles (less common)
  • Rectal pain or bleeding (when contracted in the rectum)

Symptoms in women can include:

  • Abnormal vaginal discharge
  • Burning sensation during urination
  • Pain during intercourse (less common)
  • Abdominal pain (less common)
  • Bleeding between periods (less common)
  • Rectal pain or bleeding (when contracted in the rectum)

For both men and women, chlamydia is commonly asymptomatic, meaning that it displays no symptoms at all. 

Who is at risk for chlamydia?

This STD is particularly common in young people. According to a CDC report, “chlamydia prevalence among sexually active persons aged 14-24 years is nearly three times the prevalence among those aged 25-39 years.” It is more prevalent among young women because at that age the cervix is still developing and is much more susceptible to the bacteria. Additionally, the vagina and cervix provide more surface area than the penis, which makes it easier for women to contract the bacteria.

Whether chlamydia symptoms are present or not, untreated chlamydia can travel to the upper genital tract and cause serious health problems. In women, chlamydia can lead to pelvic inflammatory disease (PID) and cause permanent damage leading to infertility or potentially fatal ectopic pregnancy. In men, untreated cases can lead to epididymitis, which can, but very rarely does, cause sterility.

Chlamydia can be Treated and Cured with Antibiotics

Individuals diagnosed with chlamydia should abstain from sexual activity for one week after finishing antibiotics. Keep in mind that it is possible to become reinfected with chlamydia after receiving treatment. This is why it is crucial for partners of those who have chlamydia to also get tested and treated if found positive. Chlamydia often occurs along with gonorrhea (another bacterial STD). If you have one of these STDs, you might have the other because the risk factors and symptoms are very similar. Getting tested for both is important.

Whether or not symptoms are present, testing or screening for chlamydia can be done as early as 24 hours after exposure. The incubation times vary from person-to-person; for the most accurate results, get tested two weeks after initial exposure. If you test positive for chlamydia, it is advised to get retested two weeks after completing treatment to be sure that all of the Chlamydia trachomatis bacteria is cleared from your system.

How do you test for chlamydia?

Nucleic Acid Amplification (NAA)
The three NAA tests described below (urine, swab, and DFA) work by finding the DNA of chlamydia bacteria. Because NAA tests search for the bacteria’s genetic material, it is very unlikely that a false-positive test result will occur. The incubation period for chlamydia is 1-5 days, so wait at least five days after potential chlamydia exposure before getting tested to ensure the most accurate results possible.

Urine samples (recommended test method)

  • Testing via urine samples needs to consist of first-catch urine (approximately 20-30mL of the initial urine stream). Patients should not include more than the first-catch in the collection cup to avoid diluting the sample.
  • Patients should not urinate for at least one hour prior to providing a sample.
  • Female patients should not cleanse the labial area prior to providing the specimen.

Swab cultures

  • Endocervical swab
  • Male urethral swab
  • Vaginal swab
  • Rectal swab
  • Pharyngeal swab (throat swab) if the throat is infected

Direct Fluorescent Antibody (DFA)

  • Swab cultures
  • Endocervical swab
  • Male urethral swab
  • Rectal swab
  • Neonates conjunctival swab

Why shouldn’t you get tested for chlamydia via a blood test?

Testing chlamydia with a blood test requires that a small blood sample is drawn and then tested for antibodies to the chlamydia bacteria: Chlamydia trachomatis. Chlamydia is not a blood-borne disease or infection, but the body creates antibodies to respond to various diseases and infections, and these can be found in the blood. The test can detect if antibodies to chlamydia are present, but these antibodies could be the result of a previous chlamydia infection. This would result in a false positive. Because chlamydia blood tests cannot tell for certain if an individual has chlamydia at the time of the test, only whether or not the individual has had it in the past, this type of test should not be used to diagnose chlamydia. 

Enzyme-linked immunosorbent assay (ELISA); Antibodies, IgM

  • IgM antibodies are found mainly in the blood and lymph fluid; they are the first antibody to be made by the body to fight a new infection.
  • This blood sample’s results should not be used as a diagnostic procedure without confirmation of the diagnosis by another medically established diagnostic product or procedure.

Enzyme immunoassay (EIA); Antibodies, IgG

  • IgG antibodies are the most abundant type of antibody; they are found in all body fluids and protect against bacterial and viral infections.

Cell Culture and Subsequent Detection of Chlamydia by Fluorescent Antibody Test Method

  • A culture allows the chlamydia bacteria to grow, but results take longer (typically 5 to 7 days) than the other tests and must be done in a lab. 

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  • Although culture is the legal standard, it is not the gold standard for the detection of Chlamydia trachomatis.
  • Women should not douche or use vaginal creams/medicines for 24 hours before having a chlamydia test.
  • Test options for cell cultures include:
    • Conjunctival swab
    • Cervical swab
    • Rectal swab
    • Posterior nasopharynx/throat swab
    • Urethral swab

Key Takeaways:

  • Chlamydia is the most common bacterial STD in the United States.
  • Chlamydia is a curable bacterial STD that doesn’t usually show signs or symptoms.
  • Chlamydia can cause infertility in women and sterility in men if left untreated.
  • Chlamydia can be transmitted to newborns during delivery and cause serious health complications like blindness and pneumonia.
  • Chlamydia is particularly common in young people (aged 14-24) and is especially prevalent among young women.
  • Co-infection of chlamydia and gonorrhea is common.
  • Chlamydia can infect the genitals, rectum, throat, and eyes.
  • Nucleic Acid Amplification (NAA), via either urine or swab, is considered the best option in testing for chlamydia.
  • Get tested for chlamydia! It is curable and easily treated.

Read Section 4 on Gonorrhea and Gonorrhea Testing

Medically Reviewed by on July 31, 2023

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Author: Nick Corlis

Nick Corlis is a writer, marketer, and designer. He graduated from Texas State University in San Marcos, Texas, with a degree in Digital Communications. Nick is proud to be able to help eliminate the stigma of STD testing through his writing and is always trying to advocate the importance of your sexual health. Before STDcheck, his favorite way to develop his writing skills was by accepting various writing jobs in college and maintaining multiple blogs. Nick wears many hats here at STDcheck, but specifically enjoys writing accurate, well-researched content that is not only informative and relatable but sometimes also contains memes. When not writing, Nick likes to race cars and go-karts, eat Japanese food, and play games on his computer.