Chlamydia trachomatis

Keywords

• trachoma

• mass drug administration

• blindness

Keywords

• cervicitis

• urethritis

• salpingitis

• nucleic acid amplification test

Epidemiology

There are an estimated 3 million new cases of chlamydial sexually transmitted infections each year in the United States. C. trachomatis is a major cause of epididymitis and is the cause of 23–55% of all cases of nongonococcal urethritis, although the proportion of chlamydial nongonococcal urethritis has been gradually declining. As many as 50% of men with gonorrhea may be coinfected with C. trachomatis. The prevalence of chlamydial cervicitis among sexually active women is 2–35%. Rates of infection among girls 15-19 yr of age exceed 20% in many urban populations but can be as high as 15% in suburban populations as well.

Children who have been sexually abused can acquire anogenital C. trachomatis infection, which is usually asymptomatic. However, because perinatally acquired rectal and vaginal C. trachomatis infections can persist for 3 yr or longer, the detection of C. trachomatis in the vagina or rectum of a young child is not absolute evidence of sexual abuse.

Clinical Manifestations

The trachoma biovar of C. trachomatis causes a spectrum of disease in sexually active adolescents and adults. Up to 75% of women with C. trachomatis have no symptoms of infection. C. trachomatis can cause urethritis (acute urethral syndrome), epididymitis, cervicitis, salpingitis, proctitis, and pelvic inflammatory disease. The symptoms of chlamydial genital tract infections are less acute than those of gonorrhea, consisting of a discharge that is usually mucoid rather than purulent. Asymptomatic urethral infection is common in sexually active men. Autoinoculation from the genital tract to the eyes can lead to concomitant inclusion conjunctivitis.

Diagnosis

Diagnosis of genital chlamydial infection is now accomplished by nucleic acid amplification tests (NAATs). These tests have high sensitivity, perhaps even detecting 10–20% greater than culture, while retaining high specificity. 6 FDA-approved NAATs are commercially available for detecting C. trachomatis , including polymerase chain reaction (PCR; Amplicor Chlamydia test, Roche Molecular Diagnostics, Nutley, NJ), strand displacement amplification (ProbeTec, BD Diagnostic Systems, Sparks, MD), transcription-mediated amplification (Amp CT, Hologic, San Diego, CA), and GeneXpert CT/NG assay (Cepheid, Sunnyvale, CA). PCR and strand displacement amplification are DNA amplification tests that use primers that target gene sequences on the cryptogenic C. trachomatis plasmid that is present at approximately 10 copies in each infected cell. Transcription-mediated amplification is a ribosomal RNA amplification assay. GeneXpert is an on-demand qualitative real-time PCR. All these assays are also available as coamplification tests for simultaneously detecting C. trachomatis and Neisseria gonorrhoeae.

The available commercial NAATs are FDA approved for cervical and vaginal swabs from adolescent girls and women, urethral swabs from adolescent boys and men, and urine from adolescents and adults. Use of urine avoids the necessity for a clinical pelvic examination and can greatly facilitate screening in certain populations, especially adolescents, although several studies have now demonstrated that endocervical specimens and vaginal swabs are superior to urine for NAAT. Self-collected vaginal specimens appear to be as reliable as specimens obtained by a healthcare professional.

Data on use of NAATs for vaginal specimens or urine from children are very limited and insufficient to allow making a recommendation for their use. The CDC recommends that NAATs be used as an alternative to culture only if confirmation is available. Confirmation tests should consist of a second FDA-approved NAAT that targets a different gene sequence from the initial test.

The etiology of most cases of nonchlamydial nongonococcal urethritis is unknown, although Ureaplasma urealyticum and possibly Mycoplasma genitalium are implicated in up to one-third of cases (see Chapter 251 ). Proctocolitis may develop in individuals who have a rectal infection with an LGV strain (see Chapter 253.4 ).

Treatment

The first-line treatment regimens recommended by the CDC for uncomplicated C. trachomatis genital infection in men and nonpregnant women include azithromycin (1 g PO as a single dose) and doxycycline (100 mg PO twice a day for 7 days). Alternative regimens are erythromycin base (500 mg PO 4 times a day for 7 days), erythromycin ethylsuccinate (800 mg PO 4 times a day for 7 days), ofloxacin (300 mg PO twice a day for 7 days), and levofloxacin (500 mg PO once daily for 7 days). The high erythromycin dosages might not be well tolerated. Doxycycline and quinolones are contraindicated in pregnant women, and quinolones are contraindicated in persons younger than 18 yr. For pregnant women, the recommended treatment regimen is azithromycin (1 g PO as a single dose) or amoxicillin (500 mg PO 3 times a day for 7 days). Alternative regimens for pregnant women are erythromycin base (250 mg PO 4 times a day for 14 days) and erythromycin ethylsuccinate (800 mg PO 4 times a day for 7 days or 400 mg PO 4 times a day for 14 days).

Empirical treatment without microbiologic diagnosis is recommended only for patients at high risk for infection who are unlikely to return for follow-up evaluation, including adolescents with multiple sex partners. These patients should be treated empirically for both C. trachomatis and gonorrhea.

Sex partners of patients with nongonococcal urethritis should be treated if they have had sexual contact with the patient during the 60 days preceding the onset of symptoms. The most recent sexual partner should be treated even if the last sexual contact was more than 60 days from onset of symptoms.