By Dr Ananya Mandal, MD
Chlamydia is one of the most common sexually transmitted infections and can be contracted through unprotected vaginal, oral or anal sexual intercourse with an infected person.
Around 70% to 80% of women and about 50% of men with the infection do not display symtpoms, meaning chlamydia is easily spread to unsuspecting sexual partners by individuals who are unaware they have the disease. Chlamydia screening plays an important role in the detection and treatment of this infection to prevent long term consequences such as infertility.
The bacteria are usually detected on analysis of a urine sample or a genital swab. For the swab, a cotton bud is used to gently wipe the area and collect some cells, which are then checked for the bacteria under a microscope.
In women, a urine sample is often enough to check for chlamydia infection. Swabs may also be taken from the cervix, inside the lower vagina or the opening of the urethra.
In men, a urine samples is also usually adequate but swabs may be taken from the opening of the urethra at the tip of the penis.
Previously, the cells from urine and swab samples were allowed to grow in culture media and if colonies of chlamydia grew, infection was confirmed. This however was a lengthy process. The main tests for chlamydia that are used today are the nucleic acid amplification tests (NAATs) which include:
- Polymerase chain reaction (PCR)
- Transcription mediated amplification (TMA)
- DNA strand displacement amplification (SDA)
These test can be perfomed using the urine, swab samples or rectal specimens.
Reviewed by Sally Robertson, BSc
Last Updated: Jan 14, 2014