Dr Natalie Renaud, Registrar, and Dr Susan Bray, Sexual Health Physician, Sexual Health Clinic, Hamilton, New Zealand. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. September 2019.
Chlamydia is a sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis with the serotypes D-K.
Chlamydia serotypes L1–L3 cause lymphogranuloma venereum (LGV), which is discussed separately.
Chlamydia is a very common STI.
Risk factors include:
Chlamydia may cause very mild symptoms or no symptoms at all; asymptomatic infection occurs in approximately 70% of women and 50% of men.
In men, the most common signs and symptoms are:
In women, the most common signs and symptoms are:
Chlamydia infections can also occur in the rectum, the eyes, and in the throat.
Rectal infection usually occurs in men who have sex with men (MSM). It can also occur in heterosexual women who receive anal sex. Rectal chlamydia in females who do not practice anal sex is thought to be a result of the spread of the infection from the vagina. Rectal chlamydia is usually asymptomatic, but can infrequently cause anal discharge and discomfort.
Chlamydia conjunctivitis can occur in adults, where it is sexually acquired. It can also occur in newborn babies due to mother-to-child transmission. Throat chlamydia infection is usually asymptomatic.
Chlamydia infection can lead to complications of variable severity and duration, particularly following multiple infections over time.
The possible complications in men include:
The possible complications in women include:
Mother-to-child transmission can result in chlamydia conjunctivitis and pneumonia in newborn babies.
A triad of reactive arthritis, conjunctivitis and urethritis is known as Reiter syndrome.
In symptomatic individuals, examination findings may include urethral discharge, abnormal vaginal discharge, cervicitis and contact bleeding, tenderness on bimanual examination (cervical excitation, adnexal tenderness) and rectal discharge. As these findings can also occur with other STIs, laboratory tests are required to confirm the diagnosis of chlamydia.
In women, clinical specimens may include:
A urine sample is not routinely recommended in women because the bacterial load in urine is much less than in men.
In men, clinical specimens may include:
Rectal and pharyngeal swabs can be taken by a clinician or the patient. Proctoscopy should be performed if there are rectal symptoms.
Tests for chlamydia infection may include:
Individuals receiving treatment for chlamydia should abstain from sex for at least seven days.
Note that doxycycline is contraindicated in pregnancy and azithromycin is associated with QT prolongation.
Proctitis, epididymo-orchitis and pelvic inflammatory disease are treated by an extended course of empiric antimicrobial therapy while waiting for test results.
The treatment should cover other possible causes of these presentations such as gonorrhoea. Supportive measures and clinical review are required.
The management of chlamydia includes a full sexual health check to look for other STIs and the notifications, treatment and testing of sexual contacts.
If the patient is pregnant or has rectal chlamydia, a test of cure (TOC) by NAAT should be performed at least four weeks after completion of treatment. If taken earlier, a false positive may occur due to remnant chlamydial DNA. Re-testing is recommended in 3 months as re-infection is extremely common.
As for other STIs, the risk of acquiring chlamydia infection is reduced by safe-sex practices including limiting the number of sexual partners, using condoms and avoiding re-infection by not having sexual contact with untreated sexual partners.
If you think you are infected, stop any sexual contact and see your usual doctor or a specialist clinician at a sexual health clinic.
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