Chlamydia trachomatis infection
Chlamydia trachomatis is the most commonly reported bacterial sexually transmitted infection in the United States, frequently asymptomatic, and diagnosed by nucleic acid amplification testing of urine or genital/rectal/oropharyngeal swabs. Uncomplicated genital infection is treated with a single dose of azithromycin or a course of doxycycline, complications include pelvic inflammatory disease and epididymitis, and LGV serovars require a 21-day course and are an increasing cause of proctitis.
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What this article covers
- Overview
Chlamydia trachomatis is the most commonly reported bacterial sexually transmitted infection (STI) in the United States, causing cervicitis, urethritis, proctitis, epididymitis, pelvic inflammatory…
- Epidemiology
Chlamydia, gonorrhea, and syphilis have all increased at an alarming rate in the United States, with chlamydia the most commonly reported bacterial STI.
- Risk factors
Age under 25 years, the single strongest demographic risk factor.
- Pathophysiology
Chlamydia trachomatis is an obligate intracellular bacterium that infects columnar epithelial cells of the endocervix, urethra, rectum, conjunctiva, and oropharynx, producing mucosal inflammation with mucopurulent discharge.
- Clinical features
Cervicitis: many women are asymptomatic; when symptomatic, vaginal discharge and intermenstrual or postcoital bleeding predominate.
- Differential diagnosis
Gonorrhea (Neisseria gonorrhoeae): the most important overlapping cause of cervicitis, urethritis, proctitis, and PID; gram-negative intracellular diplococci on Gram stain confirm it, though…
- Diagnosis
Chlamydia trachomatis genital infection is confirmed by NAAT, the preferred screening and diagnostic method, performed on first-catch urine (men and women) or endocervical/urethral swabs, with…
- Management
First, for uncomplicated cervicitis, urethritis, or proctitis, treat with azithromycin 1 g PO as a single dose (preferred), or doxycycline 100 mg PO twice daily for 7 days (extend doxycycline to 21…
- Complications
Pelvic inflammatory disease and its sequelae: infertility, chronic pelvic pain, and ectopic pregnancy.
- Prognosis
Uncomplicated genital chlamydia responds well to a single dose of azithromycin or 7 days of doxycycline, with a favorable prognosis when treated promptly.
- Prevention
Screen all sexually active women younger than 25 years annually; screen women 25 years and older with STI risk factors.
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Related articles
- Pelvic inflammatory disease
Pelvic inflammatory disease is an ascending polymicrobial infection of the upper female genital tract, most often caused by Neisseria gonorrhoeae, Chlamydia trachomatis, or Mycoplasma genitalium, diagnosed clinically on uterine, adnexal, or cervical motion tenderness. Most women are treated as outpatients with a single dose of ceftriaxone plus 14 days of doxycycline, while parenteral cefotetan or cefoxitin plus doxycycline, or clindamycin plus gentamicin, is reserved for hospitalized patients, with tubo-ovarian abscess and infertility among the major complications of delayed treatment.
- Mycoplasma genitalium infection
Mycoplasma genitalium is an emerging sexually transmitted pathogen and a leading cause of nongonococcal, nonchlamydial urethritis in men and of cervicitis and pelvic inflammatory disease in women. Diagnosis requires nucleic acid amplification testing, and treatment is resistance-guided, with doxycycline lead-in therapy followed by extended azithromycin or moxifloxacin because macrolide resistance is increasingly common.
- Trichomonas vaginalis infection
Trichomonas vaginalis is a flagellated protozoan sexually transmitted infection that presents with malodorous frothy yellow-green discharge and a strawberry cervix but is frequently asymptomatic, especially in men. Diagnosis rests on nucleic acid amplification testing of vaginal secretions, and treatment is a single 2 g oral dose of metronidazole or tinidazole with partner treatment and retesting in 3 months for high reinfection rates.
- Syphilis (Treponema pallidum infection)
Syphilis is a sexually transmitted infection with the spirochete Treponema pallidum that progresses through painless chancre (primary), disseminated rash and condyloma lata (secondary), latent, and tertiary stages including neurosyphilis, diagnosed by paired nontreponemal and treponemal serology and treated with a single dose of intramuscular benzathine penicillin G for early disease.
- Infectious genital ulcers
Infectious genital ulcers are caused chiefly by herpes simplex virus and syphilis in the United States, with chancroid, lymphogranuloma venereum, and granuloma inguinale as less common causes, distinguished by ulcer pain, number, and associated lymphadenopathy, and worked up with an ordered panel of HSV NAAT, syphilis serology or darkfield, and targeted testing since a substantial minority of ulcers have no identified cause and empiric therapy is often required.
- Human papillomavirus (HPV) infection
Human papillomavirus is a nonenveloped DNA virus with low-risk types (6, 11) that cause warts and high-risk types (16, 18, and others) that drive cervical, anal, vulvar, penile, and oropharyngeal cancer, prevented by 9-valent vaccination and managed by type-specific screening rather than treatment of the virus itself.