Background

Chlamydia trachomatic infection is the most prevalent bacteria, sexually transmitted infection in the UK, particularly in young adults. Risk factors for non-LGV C. trachomatis infection: <25 years of age, having a new sexual partner or more than one sexual partner in the past and inconsistent use of condoms. NAAT is recommended for all diagnostic and screening scenarios.

When to test

Type of specimen:

Urine, vulvo-vaginal swabs, urethral swabs, endocervical swabs, rectal swabs, oropharyngeal swabs. Note: First-void urine should be avoided.

Laboratory diagnosis/sampling:

The sampling should relate to the type of sexual activity reported and the patient group.

Type of sex
Patient Oral Vaginal Anal
MSM Receptive:
oropharyngeal swab;
Insertive: 1st void urine		   Insertive peno-anal: 1st
void urine
Receptive peno-anal:
rectal swab
Receptive oro-anal:
rectal swab
Heterosexual male Fellatio: 1st void urine 1st void urine (held for a minimum of one hour, the first 20mL sample upon subsequent urination). Peno-anal: 1st void
urine
Female Fellatio: Consider oropharyngeal swab Self-taken V/V swab (may be self-collected and posted). Receptive: consider rectal swab

When? Patient should be offered testing when they first present. If there has been possible sexual exposure within the previous two weeks, patient should return for a repeat test two weeks following exposure. Where results are likely to have medicolegal significance, specimens should be handled in accordance with Royal College Pathologist’ guidance.

When not to test

Test of cure (TOC) is not recommended after treating uncomplicated genital Chlamydia infection.

When to repeat a test

All patients diagnosed with C trachomatis should been encouraged to have screening for other STIs including HIV and where indicated hepatitis B screening.

References and further reading

  1. Public Health England. UK Standards for Microbiology Investigations V 37 - Chlamydia trachomatis infection: testing by nucleic acid amplification tests (NAAT) [Internet]. 2014 [revised 17 Jan 2017; cited 2022 Oct 04]. Available from: https://www.gov.uk/government/publications/smi-v-37-chlamydia-trachomatis-infection-testing-by-nucleic-acid-amplification-test-naat
  2. UK Standards for Microbiology Investigations (UK SMI) [Internet]. UK Health Security Agency; 2014. general information; [updated 2022 Apr; cited 2022 Oct 04]. Available from: https://www.gov.uk/guidance/uk-standards-for-microbiology-investigations-smi-quality-and-consistency-in-clinical-laboratories
  3. Chlamydia: surveillance, data, screening and management [Internet]. UK Health Security Agency; 2011. [updated 2022 Mar; cited 2022 Oct 04]. Available from: https://www.gov.uk/government/collections/chlamydia-surveillance-data-screening-and-management
  4. National Chlamydia Screening Programme (NCSP) [Internet]. UK Health Security Agency; 2011. [updated 2022 Mar; cited 2022 Oct 04]. UK Health Security Agency; 2003. [updated 2022 Mar; cited 2022 Oct 04]. Available from: https://www.gov.uk/government/collections/national-chlamydia-screening-programme-ncsp
  5. Clinical Knowledge Summaries [Internet]. National Institute for Health and Care Excellence; 2000. Chlamydia - uncomplicated genital [updated 2022 Apr; cited 2022 Oct 04]. Available from: https://cks.nice.org.uk/topics/chlamydia-uncomplicated-genital/

Editorial Information

Last reviewed: 01/04/2023

Next review date: 01/04/2024

Author(s): Vanda Plecko.

Version: 1

Approved By: National Demand Optimisation Group - Education Short Life Working Group