Report name

Chlamydia trachomatis amplified RNA

Useful for

• Detection of Chlamydia trachomatis
• This test is not intended for use in medico-legal applications.
• This test is not useful for the detection of Chlamydia pneumoniae.

Clinical information

Chlamydia is caused by the obligate intracellular bacterium Chlamydia trachomatis and is the most common bacterial sexually transmitted infection (STI) in the United States. In 2010, 1.3 million documented cases were reported to the Centers for the CDC. Since 3 out of 4 infected women and 1 out of 2 infected men will be initially asymptomatic, it is believed that the actual prevalence of the disease is much higher than reported. The organism causes genitourinary infections in women and men and may be associated with dysuria, as well as vaginal, urethral, or rectal discharge.

In women, complications include pelvic inflammatory disease, salpingitis, and infertility. Approximately 25% to 30% of women who develop acute salpingitis become infertile. Complications among men are rare but include epididymitis and sterility. Rarely, genital chlamydial infection can cause arthritis with associated skin lesions and eye inflammation (Reiter’s syndrome). C. trachomatis can be transmitted from the mother during delivery and is associated with conjunctivitis and pneumonia in the newborn. Finally, C. trachomatis can cause hepatitis and pharyngitis in adults.

Once detected, the infection is easily treated with a short course of antibiotic therapy. Annual chlamydia screening is now recommended for all sexually active women aged 25 and younger and for older women with risk factors for infection, such as a new sexual partner or multiple sexual partners. The CDC also recommends that all pregnant women be screened for chlamydia infection. Repeat testing for proof of cure is not recommended after treatment with a standard treatment regimen unless patient compliance is in question, reinfection is suspected, or the patient’s symptoms persist. Repeat testing of pregnant women is also recommended 3 weeks after completion of therapy to ensure a therapeutic cure.

The culture was previously considered the gold standard test for the diagnosis of C trachomatis infection. However, the organisms are labile in vitro and precise sample collection, transport, and processing conditions are required to maintain the viability of the organism, which is necessary for successful cultivation. In comparison, nucleic acid amplification tests (NAATs) provide superior sensitivity and specificity and are now the recommended method for diagnosis in most cases. Immunoassays and Non-amplified DNA tests are also available for the detection of C. trachomatis, but these methods are significantly less sensitive and less specific than NAAT.

Improved detection rates and increased sensitivity of NAAT tests have resulted in a greater number of accurately diagnosed cases. Improved detection rates are the result of increased assay throughput. Early identification of the infection allows sexual partners to request testing and/or treatment as soon as possible and reduces the risk of spreading the disease. Timely treatment reduces the risk of infertility in women.

Interpretation

• A positive result indicates the presence of Chlamydia trachomatis rRNA.
• A negative result indicates that no rRNA for C trachomatis was detected in the sample.

The predictive value of an assay depends on the prevalence of disease in any particular population. In settings with a high prevalence of sexually transmitted diseases, positive assay results have a high probability of being true positives. In settings with a low prevalence of sexually transmitted diseases, or in any setting where a patient’s clinical signs and symptoms or risk factors are not consistent with chlamydial urogenital infection, positive results should be carefully evaluated and the Patient should be retested by other methods, if appropriate.