Chlamydia
Chlamydia trachomatis is an obligate intracellular bacterium that hijacks columnar epithelial cells of the genital tract, producing an infection so often silent that transmission and ascending damage occur before any symptom prompts a test.
In a nutshell
Chlamydia trachomatis is an obligate intracellular bacterium confined to columnar epithelium, producing infection that is silent in most patients. Silence, not virulence, is what drives both the epidemiology and the complications: undetected infection ascends to cause pelvic inflammatory disease and tubal infertility, or triggers a distant immune reaction as reactive arthritis.
Classic presentation
An asymptomatic young adult identified on opportunistic screening, or a woman with post-coital bleeding and vaginal discharge, or a man with urethral discharge and dysuria.
Key points
- Obligate intracellular life cycle confines infection to columnar epithelium (cervix, urethra, rectum, conjunctiva, pharynx), never the vagina itself.
- Most infections are asymptomatic in both sexes, which is why screening (not symptoms) is the main route to diagnosis.
- NAAT is the test of choice everywhere: first-catch urine in men, vulvovaginal or endocervical swab in women, plus extragenital swabs where exposure indicates.
- Untreated ascending infection is the leading preventable cause of tubal infertility and ectopic pregnancy in the UK.
- Partner notification is central to management: treating the index case without tracing partners simply allows reinfection.
- Reactive arthritis is immune-mediated, not physical spread: joint aspirate is sterile.
First-line investigation
Nucleic acid amplification test (NAAT): first-catch urine in men, vulvovaginal or endocervical swab in women, with extragenital swabs guided by exposure.
First-line management
A first-line course of antibiotics per BASHH guidance, combined with partner notification and advice to abstain from sex until treatment is complete.
Exam traps
- A negative vaginal swab does not exclude rectal or pharyngeal infection if there has been relevant exposure: the wrong site was sampled, not a false negative.
- Treating the index patient without arranging partner notification is incomplete management and risks reinfection.
- Reactive arthritis follows chlamydia by days to weeks and is immune-mediated: do not expect organisms in the joint.
Educational content pending clinical review. Not medical advice.