Chlamydia

Overview

Chlamydia is caused by the intracellular bacterium Chlamydia trachomatis. Infection is most often transmitted through vaginal, anal or oral sex and can also pass from a pregnant person to a newborn during birth. Because asymptomatic infection is common, screening and exposure-based testing detect many cases that would otherwise be missed. ^{[1] [2]}

Untreated cervical infection can ascend into the upper genital tract and contribute to pelvic inflammatory disease, chronic pelvic pain, tubal-factor infertility and ectopic pregnancy. In men, urethritis and epididymitis can occur. Rectal infection may cause proctitis or remain asymptomatic. These complications are the main reason clinicians treat confirmed infection promptly even when a person feels well. ^{[1] [3]}

Symptoms and warning signs

When symptoms occur, they vary by site. Cervical infection may cause abnormal vaginal discharge, bleeding after sex or between periods, pelvic discomfort or painful urination. Urethral infection may cause burning with urination or discharge. Rectal infection can cause pain, discharge or bleeding, while many rectal and throat infections have no symptoms. Severe pelvic pain, fever or testicular pain raises concern for complications that need clinical assessment. ^{[1] [3]}

Diagnosis

Nucleic acid amplification tests (NAATs) are the recommended and most sensitive tests for chlamydia. For urogenital screening, vaginal swabs are an optimal specimen in women and first-catch urine is commonly used in men; testing can also be performed at rectal or other exposed sites when clinically appropriate. Self-collected vaginal and rectal swabs can perform well on validated NAAT platforms. ^[1]

Testing decisions should reflect anatomy, pregnancy, age and sexual exposure rather than symptoms alone. A chlamydia diagnosis is also an opportunity to test for other STIs such as gonorrhea, syphilis and HIV according to guideline recommendations and individual risk. ^{[1] [2]}

Complications of untreated infection

For people with a uterus and fallopian tubes, the most consequential complication is pelvic inflammatory disease. Tubal inflammation and scarring can reduce fertility and increase ectopic-pregnancy risk. Some upper-genital-tract infection is subclinical, so absence of dramatic pelvic symptoms does not guarantee absence of risk. ^{[1] [3]}

Other complications include epididymitis in men and reactive arthritis in a small proportion of infected people. During pregnancy, untreated infection can affect the pregnant person and can be transmitted to the newborn, causing conjunctivitis or pneumonia. ^[1]

Screening and who is tested

CDC recommends annual chlamydia screening for sexually active women younger than 25 and for older women at increased risk, with additional recommendations for pregnancy and for people whose sexual practices or local epidemiology place them at higher risk. Screening recommendations vary by country, so local preventive-care guidance should be used. ^{[1] [2]}

Treatment and management

Confirmed chlamydia should be treated promptly with an effective antibiotic regimen. CDC recommends doxycycline for seven days for uncomplicated infection in adolescents and adults, with alternatives used in selected circumstances. Pregnancy has a different recommended regimen, and treatment choice should account for contraindications, adherence and the infected anatomical site. ^[1]

To reduce transmission and reinfection, people should avoid sexual contact until the recommended post-treatment interval has passed and until partners have been treated. Recent sexual partners should be evaluated and treated according to local partner-management guidance; expedited partner therapy is an option in some jurisdictions. ^[1]

Test of cure, retesting and reinfection

For nonpregnant people treated with a recommended regimen, a routine test of cure is generally unnecessary unless adherence is uncertain, symptoms persist or reinfection is suspected. NAAT testing too soon after therapy can remain positive from nonviable organisms. CDC recommends retesting about three months after treatment because repeat infections are common. ^[1]

During pregnancy, CDC recommends a test of cure about four weeks after treatment and repeat testing later because persistent infection can have consequences for both mother and infant. ^[1]

Reducing future risk

Consistent condom use, regular screening when recommended, testing after a new or known infected partner, and prompt partner treatment reduce the chance of repeat infection. A previous treated infection does not create reliable immunity, so a person can acquire chlamydia again. ^{[2] [3]}

Sources

1. CDC — Chlamydial Infections — STI Treatment Guidelines
2. CDC — STI Screening Recommendations
3. CDC — About Chlamydia
4. WHO — Chlamydia fact sheet

This article is based on trusted medical sources and is awaiting clinician review. It is not a substitute for personalized medical advice.