Chlamydia trachomatis, commonly known as simply chlamydia, is an obligate intracellular bacteria causing a sexually transmitted infection (STI). It is the most common STI in the UK.
Prevalence is highest amongst young, sexually active adults (15-24 years old) with 134,000 diagnoses made in 2019 alone.
It has an incubation period of approximately 7-21 days but a large majority of cases are asymptomatic.
Pathophysiology
Transmission is via unprotected vaginal, anal or oral sex. Penetration is not always necessary and it can be spread via simple skin-to-skin contact of the genitalia. Infected semen/vaginal fluid entering the eye can cause chlamydial conjunctivitis. It may be also transmitted vertically from mother to baby during labour.
Chlamydia has many forms, namely the elementary body and reticular body. Ienters the host cell as an elementary body which is its infectious form. Once inside the cell it becomes a reticular body which is not infectious, but this form is able to replicate. Following replication, these reticular bodies mature back to elementary bodies, and following cell rupture the elementary bodies infect other cells resulting in inflammation and tissue damage.
🔢 Classification
There are serotypes that range from A-L:
- Serotypes A-C – cause trachoma.
- Serotypes D-K – responsible for classical genitourinary infection.
- Serotypes L1-L3 – cause lymphogranuloma venereum (LGV).
⚠️ Risk factors
- <25 years old
- New sexual partner
- More than one sexual partner in the last year
- Lack of consistent condom use
😷 Presentation
It is asymptomatic in many cases, especially in women (70%) with men being asymptomatic around 50% of the time.
Symptoms can differ from women to men of course:
Symptoms in women
- Discharge - may be purulent.
- Vaginal bleeding
- Deep dyspareunia
- Dysuria
- Pelvic pain
- Cervicitis
Symptoms in men
- Dysuria
- Muculopurulent urethral discharge
- Urethritis
- Epididymo-orchitis
🔍 Investigations
🏆 Nucleic acid amplification tests (NAAT) are the gold-standard investigation. However, the method of obtaining samples differs between men and women:
Women
- 🥇 Vulvovaginal swab or endocervical swab is the sample of choice in women. A swab is inserted 5cm into the vagina and rotated for 10-30 seconds. Vulvovaginal (introitus) swab is preferred.
- 🥈 First-catch urine is the alternative. Urine should have been held in the bladder for at least 1 hour and the first 20mL of urine should be tested.
Men
- 🥇 First-catch urine
- 🥈 Urethral swab - a swab is inserted into the urethra about 2-4cm, rotated once and then sampled.
👀 Screening
The National Chlamydia Screening Programme (NCSP) is a screening programme offered to asymptomatic individuals such as:
- Sexual partners of individuals with proven or suspected chlamydia
- All sexually active people younger than 25.
- All people concerned about a sexual exposure.
- People under 25 years old who have been treated for chlamydia in the past 3 months.
- Individuals with >2 sexual partners in the past 12 months.
- All women seeking to terminate pregnancy.
- All men and women attending genito-urinary medicine clinics.
However, it is mostly opportunistic screening when patients come in for other reasons.
🧰 Management
When treating chlamydia the patient as well as their current partner(s) need to be treated to reduce risk of re-infection and transmission. Sex should be avoided until treatment has been completed.
Sexual partners from the last 6 months should be contacted as well. Confirmed contacts should be offered treatment, then investigations (treat then test).
- 🥇 Doxycycline - 100mg BD for 7 days is the first-line option. However, this is contraindicated in pregnancy and breastfeeding.
- It used to be azithromycin, but because of coexisting mycoplasma genitalium infection with chlamydia, doxycycline is now preferred.
- 🥈 Azithromycin - 1g OD for 1 day, then 500mg OD for 2 days.
- 🥉 Erythromycin - 500mg BD for 10-14 days.
Pregnant women
- 🥇 Azithromycin - this is the drug of choice in pregnancy.
- Erythromycin
- Amoxicillin
🚨 Complications
- Pelvic inflammatory disease - includes endometritis and salpingitis
- It occurs in 16% of women with untreated chlamydia. It increases the risk of infertility, ectopic pregnancy and chronic pelvic pain.
- Epididymo-orchitis
- Lymphogranuloma venereum
- Sexually acquired reactive arthritis (SARA)
- Perihepatitis (Fitz-Hugh-Curtis syndrome) - this is inflammation of the hepatic capsule presenting with RUQ pain that may refer to the right shoulder.
- Pregnancy complications
- Pre-term birth and low birth weight
- Infections of eyes, lungs, genitals and nasopharynx in neonates.
- Initial symptoms are conjunctival hyperaemia, eyelid oedema, photophobia, and watery or purulent discharge. Infants may develop symptoms of pneumonia by the age of eight weeks.
Trachoma is a form of bacterial keratoconjunctivitis caused by chlamydia trachomatis (serovars A-C). It is more common in deprived areas of the world due to poor hygiene.
😷 It presents as like any other keratoconjunctivitis with a mucopurulent discharge.
🔍 Diagnosis is purely clinical. This also has to do with the fact that it occurs primarily in resource deprived areas of the world where testing is expensive and not as readily available.
🧰 Management is simple with a one-off dose of topical azithromycin.
🚨 If not treated it can lead to conjunctival scarring and corneal abrasion.
Lmyphogranuloma venereum (LGV) is a progressive STI caused by chlamydia trachomatis (serovars L1-L3).
⚠️ It typically occurs in men who have sex with men, HIV patients and has historically been seen more in the tropics.
🔢 + 😷 It can be classified in its presentation into 3 stages:
Stage 1
- Small painless pustule that may become ulcerated later on. It usually forms on the penis or on the vulva of females.
Stage 2
- Painful inguinal lymphadenopathy
- Proctocolitis - anorectal pain, rectal bleeding, diarrhoea, constipation, tenesmus.
Stage 3
- Chronic progressive oedema
- Scarring and destructive ulceration of the genitalia
🧰 Doxycycline - 100mg PO BD for 1-3 weeks.