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Chlamydia trachomatis, Neisseria gonorrheae (CT/GC) NAT

Test Code: 30807

A special account is required to order pre-transplant testing. Contact Client Services or your account executive to set up a pre-transplant account to order this assay. Specimens should not be collected until after account has been created.

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Clinical Utility

The BD ProbeTecTM ET Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) Amplified DNA Assays, when tested with the BD ProbeTec ET System, use Strand Displacement Amplification (SDA) technology for the direct, qualitative detection of Chlamydia trachomatis and Neisseria gonorrhoeae DNA in endocervical swabs, male urethral swabs, and in female and male urine specimens as evidence of infection with C. trachomatis, N. gonorrhoeae, or of co-infection with both C. trachomatis and N. gonorrhoeae. Specimens may be from symptomatic or asymptomatic females and males. A separate Amplification Control is an option for inhibition testing (BD ProbeTec ET CT/GC/AC Reagent Pack). The BD ProbeTec ET CT/GC assays may be performed using either the BD ProbeTec ET System or a combination of the BD ProbeTec ET System  and BD ViperTM instrument. 

About Chlamydia trachomatis, Neisseria gonorrheae

Chlamydia trachomatis and Neisseria gonorrhoeae infections are the most common sexually transmitted bacterial diseases in the United States. Approximately 4 million new chlamydia cases are estimated to occur each year in the United States with worldwide estimates of approximately 50 million new cases annually.1-3 The incidence of chlamydial infections in women in the US in 1996 was 186.6 per 100,000. The total number of chlamydial infections and gonorrhea cases reported in the US in 1996 were 490,080 and 325,883, respectively.2

Chlamydiae are gram-negative, obligate intracellular bacteria. They form characteristic intracellular inclusions which can be observed in cell culture by light microscopy after special staining is applied.4 Chlamydia trachomatis causes cervicitis, urethritis, salpingitis, proctitis and endometritis in women and urethritis, epididymitis and proctitis in men. Acute infections are reported more frequently in men because women often have no symptoms of infection. It has been estimated that 70 - 80% of women and up to 50% of men who are infected experience no symptoms. Many chlamydial infections in women remain untreated which may result in low-grade inflammation in the Fallopian tubes, a leading contributor to infertility. This organism can also be transmitted in the birth canal, potentially resulting in infant conjunctivitis and/or chlamydial pneumonia in newborns.4,5

Neisseria gonorrhoeae are gram-negative, oxidase positive diplococci which can be observed in Gram-stained smears of urethral discharges, usually within neutrophils. Culture of N. gonorrhoeae can be difficult because the organism does not survive long outside its host and is highly susceptible to adverse environmental conditions such a drying and extreme temperatures.6 Neisseria gonorrhoeae causes acute urethritis in males, which if untreated can develop into epididymitis prostatitis, and urethral stricture. In females, the primary site of infection is the endocervix. An important complication in females is development of pelvic inflammatory disease which contributes to infertility.7 Asymptomatic infections occur often in females but infrequently in males.

The current methods for detection of C. trachomatis and/or N. gonorrhoeae include culture, immunoassays, non-amplified probes, and amplified probes.4,6,7 The development of amplified methods has demonstrated two advantages over non-amplified methods: increased sensitivity, and applicability to a variety of sample types. Historically, culture has been the "gold standard" for detection of C. trachomatis. However, the culture yield varies widely among laboratories, and culture in routine practice is less sensitive than amplified methods. Combining results from multiple methods of CT detection improves accuracy for evaluating new tests in that infected and uninfected patients can be more reliably identified. For identification of GC, optimized culture methods continue to be the standard for diagnosing patients with gonococcal infections.

The BD ProbeTec ET Chlamydia trachomatis and Neisseria gonorrhoeae Amplified DNA Assays, when used with the BD ProbeTec ET System, utilize homogeneous Strand Displacement Amplification (SDA) technology as the amplification method and fluorescent energy transfer (ET) as the detection method to test for the presence of C. trachomatis and N. gonorrhoeae DNA in clinical specimens.8-10

Procedure

The BD ProbeTec ET Chlamydia trachomatis and Neisseria gonorrhoeae Amplified DNA Assays are based on the simultaneous amplification and detection of target DNA using amplification primers and a fluorescent labeled detector probe.9,10 The SDA reagents are dried in two separate disposable microwell strips. The processed sample is added to the Priming Microwell which contains the amplification primers, fluorescent labeled detector probe, and other reagents necessary for amplification. After incubation, the reaction mixture is transferred to the Amplification Microwell, which contains two enzymes (a DNA polymerase and a restriction endonuclease) necessary for SDA. The Amplification Microwells are sealed to prevent contamination and then incubated in a thermally controlled fluorescent reader which monitors each reaction for the generation of amplified products. The presence or absence of CT and GC is determined by relating the BD ProbeTec ET MOTA (Method Other Than Acceleration) scores for the sample to pre-determined cutoff values. The MOTA score is a metric used to assess the magnitude of signal generated as a result of the reaction.

This insert describes the test procedures for two assay kit configurations - the CT/GC Reagent Pack and the CT/GC/AC Reagent Pack. If the CT/GC Reagent Pack is used, each sample and control are tested in two discrete microwells: one for C. trachomatis and one for N. gonorrhoeae. If the CT/GC/AC Reagent Pack is used, each sample and control are testing in three discrete microwells: C. trachomatis, N. gonorrhoeae, and the Amplification Control. The purpose of the Amplification Control is to identify a sample that may inhibit the SDA reaction.

Test performed by VRL Eurofins, 6933 S. Revere Parkway, Centennial, CO 80112. This test has been cleared or approved for diagnostic use by the U.S. Food and Drug Administration. See package insert for more information.

Within 24 hours from receipt of specimen (Tuesday - Saturday).

Specimen Type Order Code CPT Code NY Approved Volume Assay Range Special Instructions
urine 30807 87491/87591 Yes

UPT Tube filled to lines on tube

Qualitative

  • Collect urine in a sterile urinalysis container and transfer to UPT Probetec tube filled to lines marked on the tube.
  • Can be shipped at ambient or refrigerated temperature, must be received within 30 days or frozen received within 60 days.
Shipping

All specimens must be labeled with patient's name and collection date. A Viracor/VRL Eurofins Pre-Transplant test requisition form must accompany each specimen. Multiple tests can be run on one specimen. Ship specimens FedEx Priority Overnight® to: VRL Eurofins, 6933 S. Revere Parkway, Centennial, CO 80112.

Causes for Rejection

Whole blood frozen, specimens beyond their acceptable length of time from collection as listed in the specimen handling, or specimen types other than those listed.

Specimens are approved for testing in New York only when indicated in the Specimen Information field above. The CPT codes provided are based on VRL Eurofins' interpretation of the American Medical Association's Current Procedural Terminology (CPT) codes and are provided for informational purposes only. CPT coding is the sole responsibility of the billing party. Questions regarding coding should be addressed to your local Medicare carrier. VRL Eurofins assumes no responsibility for billing errors due to reliance on the CPT codes illustrated in this material.

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