Background Information
Aetiology
Chlamydia is caused by the infection of the obligate intracellular bacterium Chlamydia trachomatis
Epidemiology
Chlamydia is the most commonly reported curable bacterial STI in the UK
Risk factors include:
- <25 y/o
- New sexual partner
- >1 sexual partner in the last year
- Lack of consistent condom use
Clinical Features
Genital Infection
Chlamydia is asymptomatic in ~70% of women and ~50% of men
| Women |
|
| Men | Symptoms in men can be very mild
|
Extra-Genital Infection (Less Common)
| Rectal chlamydia | Usually asymptomatic
If symptomatic: anal discharge and anorectal discomfort |
| Chlamydia conjunctivitis | Unilateral chronic low-grade conjunctival irritation (may be bilateral) |
| Oropharyngeal infection | Usually asymptomatic
If symptomatic: pharyngitis and sore throat |
Complications
Possible complications include:
- PIDPelvic inflammatory disease – in women (see the Pelvic Inflammatory Disease (PID) article)
- Epididymo-orchitis – in men (see the Epididymo-Orchitis article)
- Reactive arthritis
- Fitz-Hugh syndrome (peri-hepatitis)
Chlamydia infection in pregnancy is associated with adverse outcomes, including:
- Increased risk of premature rupture of membranes, pre-term delivery, and low birth weight in the infant
- Increased risk of intra-partum pyrexia and late post-partum endometritis
- Infections of the eyes, lungs, nasopharynx, and genitals in the neonate (much more serious compared to adults)
Diagnosis
Screening
According to the National Chlamydia Screening Programme (NCSP), the following should be offered a chlamydia test:
- Partner with chlamydia or symptoms of chlamydia infection
- All sexually active women <25 y/o (to be tested yearly and after having sex with a new partner)
- All sexually active women <25 y/o who attend a sexual health service / contraception service / termination of pregnancy service
Chlamydia Testing
Test of choice: NAATNucleic acid amplification test
Sample collection methods:
- Male: first pass urine (alternative: urethral swab)
- Female: vulvovaginal swab (alternative: endocervical swab or first pass urine)
Cultures are NOT taken routinely to diagnose chlamydia, unlike in gonorrhoea (see the Gonorrhoea article for more details).
Management
Refer ALL patients to GUMGenito-urinary medicine clinic / local specialist for management.
General Advice
Abstain from all sexual activity until 7 days after they and their partner(s) have completed treatment
Pharmacological Management
- 1st line: oral doxycycline 100mg BD for 7 days
- 2nd line: oral azithromycin 1g OD for 1 day followed by 500mg OD for 2 days
- 3rd line: oral erythromycin
Management in Pregnant Patients
- Discuss with GUM and specialist
- Safe antibiotic options include: azithromycin, erythromycin, amoxicillin
- Test of cure is routinely needed in pregnant patients
Doxycycline is contraindicated in pregnancy and breastfeeding.
Partner Notification
Partner notification period:
- If symptomatic men → notify all partners within the past 4 weeks (1 month) (or most recent partner if more than 4 weeks ago)
- If all other patients (i.e. asymptomatic men and women) → notify all partners within the past 6 months
Management of sexual contacts:
- Any sexual partner who tests positive for Chlamydia trachomatis should receive treatment
- Offer full STI screening, including HIV testing (and hepatitis B screening and vaccination if indicated)
Chlamydia infection has a high frequency of transmission, with concordance rates of up to 75% of partners being reported.
The partner notification period for chlamydia is 2x that of gonorrhoea
In gonorrhoea:
- Symptomatic men → 2 week lookback (vs 4 weeks in chlamydia)
- All other patients (i.e. asymptomatic men and women) → 3-month lookback (vs 6 months in chlamydia)
Follow Up
Test of Cure
Test of cure is NOT routinely recommended.
Exceptions:
- Pregnant patients
- Poor compliance
- Persistent symptoms
Test of cure should be performed at least 3 weeks after completion of treatment.
Repeat Testing
Indications:
- Offer to all <25 y/o diagnosed with chlamydia, 3-6 months after completion of treatment
- Consider if >25 y/o who are at high risk of re-infection
References
NICE CKS Chlamydia - uncomplicated genital
BASHH Chlamydia 2015
UK Health Security Agency Guidance NCSP: programme overview