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NC Department of Health and Human Services
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Virology / Serology: Chlamydia/Gonorrhea

General Information

Chlamydia trachomatis and Neisseria gonorrhoeae infections are two of the most common sexually transmitted infections worldwide. In the United States alone a total of 1,441,789 cases of C. trachomatis and 350,062 cases of N. gonorrhoeae infections were reported in 2014.

Chlamydia are nonmotile, gram-negative, obligate intracellular bacteria. C. trachomatis can cause assorted urogenital infections in addition to asymptomatic infection, which if undiagnosed could lead to pelvic inflammatory disease (PID), ectopic pregnancy, and infertility in women. Children born to infected mothers are at significantly higher risk for inclusion conjunctivitis and chlamydial pneumonia.

N. gonorrhoeae is the causative agent of gonorrheal disease. N. gonorrhoeae are nonmotile, gram-negative diplococci. The majority of gonorrheal infections are uncomplicated lower genital tract infections and may be asymptomatic. However, if left untreated in women, infections can ascend and cause PID. A smaller percentage of persons with gonococcal infections may develop Disseminated Gonococcal Infection (DGI).

The diagnostic testing for C. trachomatis and N. gonorrhoeae at the NC State Laboratory of Public Health is a nucleic acid amplification test (NAAT) that dually detects the presence of C. trachomatis RNA and/or N. gonorrhoeae RNA on a single vaginal swab specimen. Urine testing for C. trachomatis and N. gonorrhoeae is available on a limited basis to pre-approved, select sites.

Please call the Virology/Serology Unit Manager at 919-733-7544 for guidance related to the collection and submission of specimens to CDC for cases of suspected LGV.

Specimen Acceptance Policy

Chlamydia trachomatis/Neisseria gonorrhoeae laboratory services are subject to the following guidelines which have been developed to ensure proper patient management and efficient utilization of limited resources. Only the following specimens will be accepted from local health departments:

  • Vaginal swab specimens from women with syndromes compatible with C.trachomatis and/or N. gonorrhoeae infection.
  • Vaginal swab specimens from pregnant females.
  • Vaginal swab specimens from asymptomatic women, 25 years old and younger, seen in either Family Planning or Sexually Transmitted Disease clinics.
  • Vaginal swab specimens from women for retest for Chlamydia/Gonorrhea at three months post-treatment.
  • Vaginal swab specimens from women due to sex partner referral.
  • Vaginal swab specimens from women with high risk history (i.e. new partner, multiple partners, etc.).
  • Vaginal swab specimens for Chlamydia testing prior to IUD insertion.

Specimen Collection and Identification

In addition to the instructions below, an instructional PowerPoint presentation Chlamydia/Gonorrhea Vaginal Specimen Collection and Form Training PowerPoint Presentation external link is available. The purpose of the presentation is to assist in training people who collect and submit vaginal samples to the NCSLPH for Chlamydia/Gonorrhea testing. Following the instructions should result in optimal quality of test samples and the expeditious reporting of test results. The presentation may be viewed for guidance or continuing education.  To receive 1.0 contact hours of continuing education, the quiz at the end of the presentation must be completed and passed. A certificate will be issued.

Vaginal swab specimens (clinician-collected) are obtained by the following procedure:

  1. Partially peel open the swab package. Do not touch the soft tip or lay the swab  down. If the soft tip is touched, the swab is laid down, or the swab is dropped,  use a new APTIMA Vaginal Swab Specimen Collection Kit.
  2. Remove the swab.
  3. Hold the swab, placing your thumb and forefinger in the middle of the swab shaft.
  4. Carefully insert the swab into the vagina about 2 inches (5 cm) past the introitus and gently rotate the swab for 10 to 30 seconds. Make sure the swab touches the walls of the vagina so that moisture is absorbed by the swab.
  5. Withdraw the swab without touching the skin.
  6. While holding the swab in the same hand, unscrew the cap from the tube. Do not spill the contents of the tube. If the contents of the tube are spilled, use a new APTIMA Vaginal Swab Specimen Collection Kit.
  7. Immediately place the swab into the transport tube so that the tip of the swab is visible below the tube label.
  8. Carefully break the swab shaft at the scoreline against the side of the tube and discard the top portion of the swab shaft. Do not spill the contents of the tube. If the contents of the tube are spilled, use a new APTIMA Vaginal Swab Specimen Collection Kit.
  9. Tightly screw the cap onto the tube.

Patients who wish to collect their own vaginal swab specimens should be instructed as follows:

  1. Partially peel open the swab package. Do not touch the soft tip or lay the swab down. If the soft tip is touched, the swab is laid down, or the swab is dropped, request a new APTIMA Vaginal Swab Specimen Collection Kit.
  2. Remove the swab.
  3. Hold the swab in your hand, placing your thumb and forefinger in the middle of the swab shaft.
  4. Carefully insert the swab into your vagina about two inches inside the opening of the vagina and gently rotate the swab for 10 to 30 seconds. Make sure the swab touches the walls of the vagina so that moisture is absorbed by the swab.
  5. Withdraw the swab without touching the skin.
  6. While holding the swab in the same hand, unscrew the cap from the tube. Do not spill the contents of the tube. If the contents of the tube are spilled, request a new APTIMA Vaginal Swab Specimen Collection Kit.
  7. Immediately place the swab into the transport tube so that the tip of the swab is visible below the tube label.
  8. Carefully break the swab shaft at the score line against the side of the tube and discard the top portion of the swab shaft.
  9. Tightly screw the cap onto the tube. Return the tube as instructed by your doctor, nurse, or care-provider.

Urine specimens are obtained by the following procedure:

  1. The patient should not have urinated for at least 1 hour prior to specimen collection.
  2. Direct patient to provide a first-catch urine (approximately 20 to 30 mL of the initial urine stream) into a urine collection cup free of any preservatives. Collection of larger volumes of urine may result in specimen dilution that may reduce test sensitivity. Female patients should not cleanse the labial area prior to providing the specimen.
  3. Remove the cap and transfer 2 mL of urine into the urine specimen transport tube using the disposable pipette provided. The correct volume of urine has been added when the fluid level is between the black fill lines on the urine specimen transport tube label.
  4. Re-cap the urine specimen transport tube tightly. This is now known as the processed urine specimen.

Clearly label specimen transport tube with the patient´s full first and last name and either SSN, date of birth, or other unique identifier. Submitted specimens must be accompanied by a fully completed submission form DHHS Chlamydia/Gonorrhea Detection Form #4011 (PDF, 82 KB). Failure to supply the requested patient information may result in significantly delayed specimen testing or in specimens being rejected. Specimens for diagnostic testing not labeled with correct patient identification information will not be tested. Minimal patient specimen identification includes full first and last name and either SSN, date of birth, or other unique identifier. Specimens which, for any reason, are deemed unsuitable or inappropriate for diagnostic testing will not be tested. Rejected specimens will be properly stored for ten days pending verbal and/or written notification of the submitter. Unless alternate arrangements are initiated by the submitter upon notification of specimen rejection, the specimen will be discarded at the end of the holding period.

Shipment

Properly identified specimen transport tubes and completed submission forms should be sent in goldenrod-colored specimen mailers labeled CHLAMYDIA/GONORRHEA DETECTION. For detailed shipping instructions using the double mailers, see Packing Instructions Using Outer Baggie (PDF, 4.6 MB). Ship at ambient temperature by the State Courier or U.S. Mail. Vaginal swab specimens are stable for 60 days at room temperature after collection and urine specimens are stable for 30 days at room temperature after collection; however, it is advisable to ship as soon as possible to avoid delays in turn-around time of test results.

Specimen collection swab kits and goldenrod-colored specimen mailers are available through the NCSLPH online supply ordering system. Store collection materials at room temperature.

Reporting Procedure and Interpretation

Clinical specimens that test positive for chlamydia and gonorrhea will be reported as "C. trachomatis RNA detected" and "N. gonorrhoeae RNA detected", respectively. All positive results will include the comment "Therapeutic failure or success cannot be determined with this assay since nucleic acid may persist for several weeks following appropriate antimicrobial therapy." Negative laboratory results for chlamydia and gonorrhea will be reported as "C. trachomatis RNA not detected" and "N. gonorrhoeae RNA not detected", respectively. An equivocal result for either test will be reported as indeterminate, in which case, another specimen should be properly collected and submitted to resolve the status of the patient. Results should be interpreted in conjunction with patient history and clinical findings.

Chlamydia and gonorrhea test results are available within three working days after receipt of the specimen. These results can be accessed on the main page by clicking on Lab Test Results Lookup.

Data indicates the sensitivity and specificity of the CT/GC NAAT assay is nearly 100 percent. However, it must be remembered that the results of this test are not 100 percent predictive of every patient’s true infected status, and that both false negative and false positive results are a possibility.

Virology/Serology Information